- Site-Specific C(sp3)–H Aminations of Imidates and Amidines Enabled by Covalently Tethered Distonic Radical Anions
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The utilization of N-centered radicals to synthesize nitrogen-containing compounds has attracted considerable attention recently, due to their powerful reactivities and the concomitant construction of C?N bonds. However, the generation and control of N-centered radicals remain particularly challenging. We report a tethering strategy using SOMO-HOMO-converted distonic radical anions for the site-specific aminations of imidates and amidines with aid of the non-covalent interaction. This reaction features a remarkably broad substrate scope and also enables the late-stage functionalization of bioactive molecules. Furthermore, the reaction mechanism is thoroughly investigated through kinetic studies, Raman spectroscopy, electron paramagnetic resonance spectroscopy, and density functional theory calculations, revealing that the aminations likely involve direct homolytic cleavage of N?H bonds and subsequently controllable 1,5 or 1,6 hydrogen atom transfer.
- Fang, Yuanding,Fu, Kang,Shi, Lei,Zhao, Rong,Zhou, Jia
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p. 20682 - 20690
(2020/09/07)
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- Stereoinversion of Unactivated Alcohols by Tethered Sulfonamides
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The direct, catalytic substitution of unactivated alcohols remains an undeveloped area of organic synthesis. Moreover, catalytic activation of this difficult electrophile with predictable stereo-outcomes presents an even more formidable challenge. Described herein is a simple iron-based catalyst system which provides the mild, direct conversion of secondary and tertiary alcohols to sulfonamides. Starting from enantioenriched alcohols, the intramolecular variant proceeds with stereoinversion to produce enantioenriched 2- and 2,2-subsituted pyrrolidines and indolines, without prior derivatization of the alcohol or solvolytic conditions.
- Marcyk, Paul T.,Jefferies, Latisha R.,AbuSalim, Deyaa I.,Pink, Maren,Baik, Mu-Hyun,Cook, Silas P.
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p. 1727 - 1731
(2019/01/21)
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- Large-scale preparation of key building blocks for the manufacture of fully synthetic macrolide antibiotics
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Key building blocks for the production of fully synthetic macrolides have been scaled-up in first time pilot plant and kilo-lab campaigns. These building blocks have supported the discovery of new macrolide antibiotics as well as ongoing preclinical studies.
- Hogan, Philip C.,Chen, Chi-Li,Mulvihill, Kristen M.,Lawrence, Jonathan F.,Moorhead, Eric,Rickmeier, Jens,Myers, Andrew G.
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p. 318 - 325
(2018/03/21)
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- Chiral morphine quinoline compound preparation method and chiral amino acid preparation method of compound
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The invention provides chiral morpholine compounds. The structural general formula of the chiral morpholine compounds is as shown in the description. The invention further comprises a preparation method of the chiral morpholine compounds. The chiral morpholine compounds are prepared by using benzoin as a starting material, performing reductive amination, and performing chemical resolution on enantiomers and acid-catalyzed ester condensation reaction. The invention further provides amino acid compounds prepared from the chiral morpholine compounds, and a preparation method and application of the amino acid compounds.
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- Stereoretentive Addition of N-tert-Butylsulfonyl-α-Amido Silanes to Aldehydes, Ketones, α,β-Unsaturated Esters, and Imines
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Enantioenriched N-tert-butylsulfonyl-α-amido silanes were successfully reacted with aldehydes, ketones, imines, and α,β-unsaturated esters in the presence of a sub-stoichiometric amount of CsF (0.5 equiv) in 1,2-dimethoxyethane (DME) at -20 °C to afford the corresponding coupling products with up to 89 % enantiospecificity in a retentive manner. Keep your cool! Enantioenriched N-tert-butylsulfonyl-α-amido silanes were successfully reacted with aldehydes, ketones, imines, and α,β-unsaturated esters in the presence of a sub-stoichiometric amount of CsF (0.5 equiv) in 1,2-dimethoxyethane (DME) at -20 °C to afford the corresponding coupling products with up to 89 % enantiospecificity in a retentive manner.
- Mita, Tsuyoshi,Saito, Keisuke,Sugawara, Masumi,Sato, Yoshihiro
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p. 1528 - 1531
(2016/06/01)
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- Highly enantioselective hydrogenation of o-alkoxy tetrasubstituted enamides catalyzed by a Rh/(R, S)-josiphos catalyst
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Rh/(R,S)-JosiPhos complex-catalyzed asymmetric hydrogenation of o-alkoxy tetrasubstituted enamides has been achieved, and it furnished a set of β-amino alcohol analogues in high yields and excellent enantiomeric excesses (>99% conversion, up to 99% ee).This method provides valuable chiral building blocks in chiral pharmaceuticals and useful motifs for catalysts.
- Meng, Jingjing,Gao, Min,Lv, Hui,Zhang, Xumu
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supporting information
p. 1842 - 1845
(2015/04/27)
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- Readily available ruthenium complex for efficient dynamic kinetic resolution of aromatic α-hydroxy ketones
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A ruthenium complex formed from commercially available [Ru(p-cymene)Cl 2]2 and 1,4-bis(diphenylphosphino)butane catalyzes the racemization of aromatic α-hydroxy ketones very efficiently at room temperature. The racemization is fully compatible with a kinetic resolution catalyzed by a lipase from Pseudomonas stutzeri. This is the first example of dynamic kinetic resolution of α-hydroxy ketones at ambient temperature in which the metal and enzyme catalysts work in concert in one pot at room temperature to give quantitative yields of esters of α-hydroxy ketones with very high enantioselectivity.
- Agrawal, Santosh,Martinez-Castro, Elisa,Marcos, Rocio,Martin-Matute, Belen
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p. 2256 - 2259
(2014/05/06)
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- HETEROARYL ACID MORPHOLINONE COMPOUNDS AS MDM2 INHIBITORS FOR THE TREATMENT OF CANCER
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The present invention provides MDM2 inhibitor compounds of Formula (I), or the pharmaceutically acceptable salts thereof, wherein the variables are defined above, which compounds are useful as therapeutic agents, particularly for the treatment of cancers. The present invention also relates to pharmaceutical compositions that contain an MDM2 inhibitor of Formula (I).
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- Enantioselective synthesis of diaryl aziridines using tetrahydrothiophene- based chiral sulfides as organocatalysts
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This work describes catalytic and asymmetric aziridinations (15 examples, 95-98% ee) of benzyl bromide and imines via the imino Corey-Chaykovsky reaction using (thiolan-2-yl)diarylmethanol benzyl ether as an organocatalyst. The catalyst and analogues thereof were prepared through an expeditious and efficient synthetic route featuring a double nucleophilic substitution and Shi epoxidation as key steps.
- Huang, Meng-Ting,Wu, Hsin-Yi,Chein, Rong-Jie
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p. 1101 - 1103
(2014/01/17)
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- Solvent-induced reversed stereoselectivity in reciprocal resolutions of mandelic acid and erythro -2-amino-1,2-diphenylethanol
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Solvent-induced chirality switching in reciprocal optical resolution between mandelic acid (1) and erythro-2-amino-1,2-diphenylethanol (2) has been demonstrated. The stereochemistry of the deposited salts was controlled by changing the crystallization solvent from 1-PrOH or 1-BuOH to 1,4-dioxane. It was revealed from 1H NMR spectra, thermogravimetric analysis, and X-ray crystallography of the salts that an equimolar amount of the crystallization solvent was incorporated in each diastereomeric salt. On the basis of the crystal structures, it was found that both the hydrogen-bonding ability and the size of the solvent molecule played an important role. Differences in the formed hydrogen-bonding networks (columnar or sheetlike structure) and their packing manner were found to be crucial for the reversed stereoselectivity. Furthermore, pseudopolymorphic salt crystals that incorporated 1,4-dioxane were obtained during the enantioseparation of racemic 2, and their solid-state properties were examined by measurement of their IR spectra. This solvent-induced dual stereocontrol technique was successfully applied to the successive resolution process, eliminating the need to change the resolving agent for access to both enantiomers of 1 and 2.
- Shitara, Hiroaki,Shintani, Toshiki,Kodama, Koichi,Hirose, Takuji
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p. 9309 - 9316
(2013/10/08)
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- Pseudoephenamine: A practical chiral auxiliary for asymmetric synthesis
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Unrestricted: Pseudoephenamine is introduced as a versatile chiral auxiliary and an alternative to pseudoephedrine in asymmetric synthesis. It is free from regulatory restrictions and leads to remarkable stereocontrol in alkylation reactions, especially in those that form quaternary carbon centers. Amides derived from pseudoephenamine exhibit a high propensity to be crystalline substances, and provide sharp, well-defined signals in NMR spectra. Copyright
- Morales, Marvin R.,Mellem, Kevin T.,Myers, Andrew G.
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p. 4568 - 4571
(2012/06/30)
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- DRUG COMBINATIONS CONTAINING PDE4 INHIBITORS AND NSAIDS
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The present invention relates to new drug combinations which contain in addition to one or more PDE4-inhibitors at least one NSAID (=non-steroidal anti-inflammatory drug) (2), processes for preparing them and their use in treating in particular respiratory complaints such as for example COPD, chronic sinusitis and asthma. The invention particularly relates to those drug combinations which contain, in addition to one or more, preferably one PDE4 inhibitor of general formula 1 wherein X is SO or SO2, but preferably SO, and wherein R1, R2, R3 and R4 have the meanings given in claim 1, at least one NSAID (2), the preparation thereof and the use thereof for the treatment of respiratory complaints.
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- Enantiopure cyclic O-substituted phenylphosphonothioic acid: Synthesis and chirality-recognition ability
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As a new acidic selector (resolving agent), we synthesized an enantiopure O-alkyl phenylphosphonothioic acid with a seven-membered ring ((R)-5), which was designed on the basis of the results for the enantioseparation of 1-arylethylamine derivatives with acyclic O-ethyl phenylphosphonothioic acid (I). The phosphonothioic acid (R)-5 showed unique chirality-recognition ability in the enantioseparation of 1-naphthylethylamine derivatives, aliphatic secondary amines, and amino alcohols; the ability was complementary to that of I. The X-ray crystallographic analyses of the less- and more-soluble diastereomeric salts showed that hydrogen-bonding networks in the salt crystals are 21-column-type with a single exception which is cluster-type. In the cases of the 21-column-type crystals, stability of the crystals is firstly governed by hydrogen bonds to form a 21-column and secondly determined by intra-columnar T-shaped CH/π interaction(s), intra-columnar hydrogen bond(s), inter-columnar van der Waals interaction and/or inter-columnar T-shaped CH/π interaction(s). In contrast, the cluster-type salt crystal is stabilized by the assistance of inter-cluster T-shaped CH/π and van der Waals interactions. To realize still more numbers of intra- and inter-columnar and -cluster T-shaped CH/π interactions, the seven-membered ring of (R)-5 plays a considerable role. Copyright
- Ribeiro, Nigel,Kobayashi, Yuka,Maeda, Jin,Saigo, Kazuhiko
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p. 438 - 448
(2012/01/02)
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- An improved synthesis and resolution of cis- and trans-2,3-diphenyl morpholines
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An improved procedure for the synthesis of cis- and trans-2,3-diphenyl morpholines with good overall yield is described. The stereoisomers were efficiently resolved through the corresponding diastereomeric salts using tartaric acid and (R)-mandelic acid.
- Jagtap, Ravindra S.,Joshi, Navalkishore N.
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experimental part
p. 1861 - 1864
(2012/01/13)
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- A new and convenient method for reduction of oximes to amines with NaBH3CN in the presence of MoCl5/NaHSO4? H2O system
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Various aldoximes and ketoximes were efficiently reduced to their corresponding amines with NaBH3CN in the presence of MoCl 5/NaHSO4?H2O system. Reduction reactions were carried out in refluxing EtOH or DMF within 0.3-3.8 h to afford the amines in high to excellent yields.
- Kouhkan, Mehri,Zeynizadeh, Behzad
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experimental part
p. 3323 - 3326
(2012/02/04)
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- A rapid and practical protocol for solvent-free reduction of oximes to amines with NaBH4/ZrCl4/Al2O3 system
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Solvent-free reduction of various aldoximes and ketoximes to the corresponding amines was performed easily and efficiently with NaBH4 in the presence of ZrCl4 supported on Al2O3. The reactions were carried out rapidly (within 2 min) at room temperature to afford the amines in high to excellent yields.
- Zeynizadeh, Behzad,Kouhkan, Mehri
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experimental part
p. 3448 - 3452
(2012/02/01)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 58
(2010/12/31)
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- An improved and mild wenker synthesis of aziridines
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The conventional Wenker synthesis of aziridines from vicinal amino alcohols has been modified by employing mild reaction conditions. Amino alcohols were converted into their hydrogen sulfates with chlorosulfonic acid. The sulfates were cyclized with sodium hydroxide, and even with non-nucleophilic sodium carbonate. The current, improved method extends the scope of the typical Wenker synthesis and is applicable to unstable amino alcohols in hot sulfuric acid and to unstable sulfates which favor elimination and hydroxide displacement in the presence of strong base. Georg Thieme Verlag Stuttgart.
- Li, Xinyao,Chen, Ning,Xu, Jiaxi
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body text
p. 3423 - 3428
(2010/11/21)
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- Synthesis of some derivatives of 4,5-dihydrooxazoles
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Benzaldehyds with sodium amide in the presence of thiourea in tetrahydro furan at room temperature gave various 2,4,5-triphenyl-4,5-dihydrooxazoles. The thiourea-catalyzed condensation of the benzaldehyde yielded 2-amino-1,2- diphenylethanone. Reduction of 2-amino-1,2-diphenylethanone was performed with hydride from Cannizzaro reaction to give 2-amino-1,2-diphenylethanols. The 4,5-dihydrooxazole ring formation of the 2-amino-1,2-diphenylethanol and benzamide gave the desired 4,5-dihydrooxazole.
- Piri, Farideh,Ghaforinia, Nastaran,Taghavi, Mohammad,Karimian, Ramin
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p. 1403 - 1406
(2012/04/10)
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- Chiral recognition based on enantioselectively aggregation-induced emission
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(Figure Presented) Novel chiral AIE compounds bearing a tartaric acid group were synthesized. They selectively aggregated with one enantiomer of a number of chiral amines, such that one enantiomer led to strong fluorescence and another enantiomer showed no or only weak fluorescence. This was used for the quantitative analysis of enantiomeric composition.
- Zheng, Yan-Song,Hu, Yu-Jian
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scheme or table
p. 5660 - 5663
(2009/12/26)
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- Synthesis of a new series of chiral tri- and tetradentate ligands and their application in titanium-catalyzed pinacol coupling reaction
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A variety of chiral tridentate and tetradentate ligands, related to each other through stereoelectronic relationship have been synthesized. Homochiral diols and amino alcohols have been used for this purpose. Titanium complexes of these ligands have been prepared and examined for enantioselective pinacol coupling reaction.
- Chatterjee,Joshi
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p. 1475 - 1482
(2008/09/18)
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- Optically pure trans-2,3-disubstituted N-sulfinyl aziridines. Regio- and stereoselective opening mediated by the sulfinyl group
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A new entry to optically pure trans-2,3-disubstituted N-sulfinyl aziridines starting from 1,2-aminosulfides, involving formation of a sulfonium salt intermediate followed by intramolecular nucleophilic attack by the sulfinamide nitrogen atom, is reported.
- Arroyo, Yolanda,Meana, ángela,Rodríguez, J. Félix,Santos, Mercedes,Sanz-Tejedor, M. Ascensión,García-Ruano, José L.
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p. 8525 - 8532
(2007/10/03)
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- Synthesis and configurational assignment of the amino alcohol in the eastern fragment of the GE2270 antibiotics by regio- and stereoselective addition of 2-metalated 4-bromothiazoles to α-chiral electrophiles
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A synthesis of the eastern fragment of the thiazole peptide GE2270 A (1) has been developed. The synthetic approach relies on the regioselective functionalization of 2,4-dibromothiazole (5) via metalation and nucleophilic addition (at C2) or palladium-mediated cross-coupling (at C2 or C4). The stereochemistry at the N-bearing stereocenter was established by coupling of 2-metalated 4-bromothiazoles (4) to enantiomerically pure mandelic acid derivatives. Both the erythro (2) and threo (3) configurated amino alcohols were prepared with high diastereoselectivities depending on the electrophile employed. More specifically, the threo-configurated (S,R)-4-bromothiazolyl β-amino alcohol 6 was synthesized from O-TBS protected (R)-mandelonitrile in 62% yield. Its N-PMB protected (R,S)-enantiomer 20 was obtained from O-TBS protected (S)-mandelic aldehyde in 67% yield. The eryrthro-configurated (S,S)-4-bromothiazolyl β-amino alcohol 29 was prepared from O-TBS protected (S)-ethyl mandelate in four steps and 33% overall yield. The bithiazole moiety in the desired products 2 and 3 was finally established by the regioselective Negishi coupling of 2,4-dibromothiazole (5) and the 4-zincated, N-Boc protected thiazole derivatives of the diastereomeric 4-bromothiazolyl β-amino alcohols 6 and 29.
- Delgado, Oscar,Heckmann, Golo,Mueller, H. Martin,Bach, Thorsten
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p. 4599 - 4608
(2007/10/03)
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- First report for the efficient reduction of oximes to amines with zinc borohydride in the form of (Pyridine)(tetrahydroborato)zinc complex
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(Pyridine)(tetrahydroborato)zinc complex, (Py)Zn(BH4) 2, as a stable modification of zinc borohydride can easily reduce a variety of aromatic and aliphaticaldoximes or ketoximes to their corresponding amines in high to excellent yields in refluxing THF.
- Zeynizadeh, Behzad,Zahmatkesh, Karam
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p. 109 - 112
(2007/10/03)
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- Imino 1,2-Wittig rearrangement of hydroximates and its application to synthesis of cytoxazone
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The imino 1,2-Wittig rearrangement of hydroximates provides a novel method for the construction of 2-hydroxyoxime ethers. Upon treatment with LDA, Z-hydroximates smoothly underwent stereoselective rearrangement to give Z-2-hydroxyoxime ethers in good yield, which were converted into amino alcohols. On the other hand, the rearrangement of E-hydroximates gave a mixture of E- and Z-2-hydroxyoxime ethers. This method was successfully applied to a practical synthesis of cytoxazone.
- Miyata, Okiko,Koizumi, Tomoko,Asai, Hiroshi,Iba, Ryuichi,Naito, Takeaki
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p. 3893 - 3914
(2007/10/03)
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- ortho-anisylsulfonyl as a protecting group for secondary amines: Mild Ni0-catalyzed hydrodesulfonylation
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A potentially good alternative to the tosyl group (Ts) as a protecting group for amines is N-ortho-anisylsulfonyl (Ans), which is readily cleaved under mild, Ni0-catalyzed reductive conditions (see scheme, acac = acetylacetonate). N-Anisylation of primary amines followed by alkylation and deprotection provides a route to a range of secondary amines.
- Milburn, Robert R.,Snieckus, Victor
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p. 892 - 894
(2007/10/03)
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- Catalytic additions of acylsilanes to imines: An acyl anion strategy for the direct synthesis of α-amino ketones
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(Chemical Equation Presented) The addition of acylsilanes to imines catalyzed by neutral carbenes (or zwitterions) generated in situ from readily available thiazolium salts is described. The general reaction successfully utilizes acylsilanes as carbonyl anion precursors and is tolerant of a range of structural diversity on the acylsilane or imine electrophile. The overall reaction utilizes easily available precursors and directly accesses protected α-amino ketones in the correct oxidation state.
- Mattson, Anita E.,Scheidt, Karl A.
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p. 4363 - 4366
(2007/10/03)
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- Application of cyclam-capped β-cyclodextrin-bonded silica particles as a chiral stationary phase in capillary electrochromatography for enantiomeric separations
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Two novel types of substituted cyclam-capped β-cyclodextrin (β-CD)-bonded silica particles have been prepared and used as chiral stationary phases in capillary electrochromatography (CEC). The two stationary phases have a chiral selector with three recognition sites: β-CD, cyclam, and the latter's sidearm. They exhibit excellent enantioselectivities in CEC for a wide range of compounds as a result of the cooperative functioning of the anchored β-CD and cyclam. After inclusion of the metal ion (Ni2+) from the running buffer into the substituted cyclams and their sidearm ligands, the bonded stationary phases become positively charged and can provide extra electrostatic interactions with ionizable solutes and enhance the dipolar interactions with some polar neutral solutes. This enhances the host-guest interaction with some solutes and improves chiral recognition and enantioselectivity. These new types of stationary phases exhibit great potential for fast chiral separations in CEC.
- Gong, Yinhan,Lee, Hian Kee
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p. 1348 - 1354
(2007/10/03)
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- Single route to chiral syn- and anti-2-amino-1,2-diphenylethanols via a new stereodivergent opening of trans-1,2-diphenyloxirane
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Oxiranyl ring opening of trans-stilbene oxide gave rise to anti- or syn-2-bromo-1,2-diphenylethanols, using either MgBr2·Et2O or MgBr2·Et2O, NaBr, and KBr with Amberlyst 15, respectively. Starting from optically pure (R,R)-trans-stilbene oxide, (1R,2R)- and (1R,2S)-2-amino-1,2-diphenylethanols were obtained in high yield and ee.
- Lupattelli, Paolo,Bonini, Carlo,Caruso, Leonilde,Gambacorta, Augusto
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p. 3360 - 3362
(2007/10/03)
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- Stereocontrolled Reactions Mediated by a Remote Sulfoxide Group: Synthesis of Optically Pure anti-β-Amino Alcohols
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(Equation presented) A one-step synthesis of enantiomerically pure anti-1,2-amino alcohol derivatives has been achieved by reaction of prochiral oxygenated 2-p-tolylsulfinylbenzyl carbanions with N-sulfinylimines bearing the same configuration at sulfur.
- Garcia Ruano, Jose L.,Aleman, Jose
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p. 4513 - 4516
(2007/10/03)
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- Process for producing optically active 3,3,3-Trifluoro-2-Hydroxy-2-Methylpropionic acid, and salt thereof
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There are disclosed are a diastereomer salt of formula (1): a process for producing the same, a process for producing optically active 3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid of formula (2′): a novel optically active amine compound of formula (4): a novel optically active amine compound of formula (8): an imine compound of formula (7) or (11):
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- Process for producing optically active chrysanthemic acid
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The present invention provides an advantageous method for producing an optically active chrysanthemic acid. Disclosed is a method for producing an optically active chrysanthemic acid whose trans isomer ratio and optical purity are improved, which comprises reacting chrysanthemic acid having a trans isomer ratio of not less than 50% and an optical purity of not less than 10% e.e. with an optically active organic amine to optically resolve said chrysanthemic acid.
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- Optical resolution of fragrant lactones
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Optical resolution of six chiral fragrant lactones (δ-jasmine lactone, massoia lactone, tuberolactone, pentynyllactone, δ-decalactone, and γ- nonalactone) was investigated by means of either the diastereomeric salt formation method or the diastereomeric amide formation method. Using these procedures, we obtained each enantiomer from five of the six lactones, except for massoia lactone. All five lactones were obtained in a good yield and with high optical purity. Sensoric characteristics on both enantiomers and racemic modification of four lactones are given.
- Nohira, Hiroyuki,Mizuguchi, Keiko,Murata, Toru,Yazaki, Yuko,Kanazawa, Miho,Aoki, Yoshio,Nohira, Misako
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p. 1359 - 1370
(2007/10/03)
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- Method for producing optically active chrysanthemic acid
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The present invention provides an advantageous method for producing an optically active chrysanthemic acid. Disclosed is a method for producing an optically active chrysanthemic acid whose trans isomer ratio and optical purity are improved, which comprises reacting chrysanthemic acid having a trans isomer ratio of not less than 50% and an optical purity of not less than 10% e.e. with an optically active organic amine to optically resolve said chrysanthemic acid.
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- Oxazaborolidine-mediated asymmetric reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones
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Highly enantioselective reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones was conducted using oxazaborolidine derived from L-threonine and borane complexes to give β- imino alcohols and 1,2-diaryl-1,2-ethanediols in high enantiomeric purity. Subsequent reduction of the imino functionality of the former products afforded either syn- or anti-2-amino-1,2-diarylethanols in high enantiomeric purity by choosing appropriate reduction methods.
- Shimizu, Makoto,Tsukamoto, Keiko,Matsutani, Takayuki,Fujisawa, Tamotsu
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p. 10265 - 10274
(2007/10/03)
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- Stereoselective synthesis of 1,2-amino alcohols by asymmetric borane reduction of α-oxoketoxime ethers
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Asymmetric reduction of α-oxoketoxime ethers with the reagents prepared in situ from trimethyl borate and chiral amino alcohols derived from either L-proline or α-pinene was investigated. Both cyclic and acyclic α- oxoketoxime ethers were reduced to afford the corresponding chiral 1,2amino alcohols with high enantioselectivities.
- Masui, Moriyasu,Shioiri, Takayuki
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p. 5195 - 5198
(2007/10/03)
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- Development of a polymer bound Wittig reaction and use in multi-step organic synthesis for the overall conversion of alcohols to β-hydroxyamines
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An efficient combinatorial access to β-hydroxyamines suitable for automation is achieved by the mild oxidation of alcohols to aldehydes by polymer supported perruthenate (PSP), the subsequent clean olefination of the obtained aldehydes by polymer supported Wittig reagents followed by the epoxidation of the olefins by dimethyldioxirane (DMDO), and the final aminolysis of the epoxides with various amines is described.
- Bolli, Martin H.,Ley, Steven V.
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p. 2243 - 2246
(2007/10/03)
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- A convenient one-pot synthesis of 1,2-aminoalcohols
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We have developed a rapid facile synthesis of 1,2-aminoalcohols from a variety of aldehyde starting materials. This one pot synthesis proceeds via the in situ formation of cyanohydrin trimethylsilyl ethers and the subsequent addition of Grignard reagents. This method is of particular use where the initial aldehyde exhibits water solubility.
- Howarth,Lloyd,McCormac
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p. 2751 - 2759
(2007/10/03)
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- Stereodivergent approach to syn- and anti 2-amino-1,2-diarylethanols using oxazaborolidine-mediated asymmetric reduction
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Highly enantioselective reduction of 1,2-diaryl-2-benzyloxyiminoethanones was conducted using oxazaborolidine derived from L-threonine and BH3· SMe2 to give β-imino alcohols in high enantiomeric purity. Subsequent reduclion of the imino functionality afforded either syn- or anti-2-amino-1,2-diarylethanols in high enantiomeric purity by choosing appropriate reduction conditions.
- Shimizu, Makoto,Tsukamoto, Keiko,Fujisawa, Tamotsu
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p. 5193 - 5196
(2007/10/03)
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- Chiral Synthesis of L-γ-Carboxylgutamic Acid (L-Gla)
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A two step synthesis involving the use of a chiral template, benzyl (2R,3S)-(-)-6-oxo-2,3-diphenyl-4-morpholine-carboxylate (5a), provides orthogonally protected L-Gla (9) in 60percent overall yield (>99percent ee), with no resolution required.
- Schuerman, Marla A.,Keverline, Kathryn I.,Hiskey, Richard G.
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p. 825 - 828
(2007/10/02)
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- A New General Method for the Synthesis of 4-Hydroxylated 3-Aryltetrahydroisoquinolines
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3-Aryl-4-hydroxytetrahydroisoquinolines have been prepared from deoxybenzoins.The nitrosation of the latter derivatives has been improved and the catalytic reduction of the obtained oximinoketones has been carried out with the help of ultrasounds.Heterocyclization to the isoquinoline moiety occurred on the unprotected 1,2-aminoalcohol to give stereoselectively the corresponding hydroxylated heterocycle with good yield.
- SanMartin, Raul,Olivera, Roberto,Marigorta, Eduardo Martinez de,Dominguez, Esther
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p. 5361 - 5368
(2007/10/02)
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- Generation of 2-azaallyl anions by the transmetalation of N-(trialkylstannyl)methanimines. Pyrrolidine synthesis by [3 + 2] cycloadditions with alkenes
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Treatment of N-(trimethylstannyl)methanimines or N-(tri-n-butylstannyl)methanimines with methyllithium or n-butyllithium, respectively, affords 2-azaallyl anions by tin-lithium exchange. These anions undergo intermolecular or intramolecular [π4s + π2s] cycloadditions with alkenes and alkynes to generate pyrrolidines or pyrrolines after quenching with water or other electrophiles. The tin-lithium exchange method allows unstabilized 2-azaallyl anions to be generated for the first time. The lifetime of the anions is limited by a competing intermolecular side reaction. Therefore, relatively reactive alkenes and alkynes must be used, such as stilbene, styrenes, enynes, diphenylacetylene, vinyl sulfides, vinyl selenides, and vinyl silanes. The latter three types of anionophiles afford functionalized cycloadducts which may be transformed into more useful pyrrolidines by reduction, elimination, or oxidation. A synthesis of the alkaloid (±)-mesembrane was accomplished using an intramolecular 2-azaallyl anion cycloaddition.
- Pearson, William H.,Szura, Daniel P.,Postich, Michael J.
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p. 1329 - 1345
(2007/10/02)
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- Enzyme-Catalyzed Reactions, 8. - Stereoselective Synthesis of 2-Amino Alcohols from (R)- and (S)-Cyanohydrins
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erythro-2-Amino alcohols (1R,2S)- and (1S,2R)-4 may be synthesized stereoselectively by addition of Grignard compounds to cyanohydrins (R)-, (S)-1 and their O-trimethylsilyl derivatives 3, respectively, followed by hydrogenation.The threo-2-amino alcohols (1S,2S)- and (1R,2R)-4 are easily accessible by inversion at C-1 of the (1R,2S) and (1S,2R) compounds.
- Effenberger, Franz,Gutterer, Beate,Ziegler, Thomas
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p. 269 - 273
(2007/10/02)
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- Process for the production of 1,2-amino alcohols
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A process for the production of 1,2-amino alcohols, in improved yields, comprising the steps of: (1) reacting a silylated cyanohydrin compound with a Grignard reagent; (2) treating the reaction product of Step 1 with either a reducing agent, or an organolithium compound; (3) hydrolyzing the reaction product of Step 2; (4) isolating the resulting 1,2-amino alcohol. The 1,2-amino alcohols thus formed are useful as pharmaceuticals or precursors therefor.
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- Applications of Optically Active Aryl Cyanohydrins in the Synthesis of α-Hydroxy Aldehydes, α-Hydroxy Ketones and β-Hydroxy Amines
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Cyanohydrins, prepared in high optical purity from aryl aldehydes, have been converted into α-hydroxy aldehydes, α-hydroxy ketones and β-hydroxy amines without any racemization and frequently with good stereoselectivity for the erythro-diastereoisomer (>90percent) at the newly introduced stereogenic centre.
- Jackson, W. Roy,Jacobs, Howard A.,Jayatilake, Gamini S.,Matthews, Barry R.,Watson, Keith G.
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p. 2045 - 2062
(2007/10/02)
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- ASYMMETRIC SYNTHESES VI: ASYMMETRIC ALDOL REACTION OF D-CAMPHOR IMINE DERIVED FROM BENZYLAMINE
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Addition of the D-camphor imine of benzylamine to a variety of aldehydes or ketones gives diastereoselectivites ranging from 16-70percent.The d.e. value is attributed by the difference of the orientation of C-11 groups.The rotation of (5e) indicates that addition reaction occurs from the pro-R face of lithium derivative (2).
- Yaozhong, Jiang,Guilan, Liu,Jingen, Deng
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p. 1291 - 1298
(2007/10/02)
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- APPLICATIONS of ORGANOLITHIUM and RELATED REAGENTS in SYNTHESIS. Part V. Directed Metallation of Secondary Picolin- and Isonicotinamides. A Useful Method for the Synthesis of 2,3- and 3,4-Disubstituted Pyridines, Including Furopyridin-3(1H)-one and Furopyridine-1(3H)-one
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The metallation reaction of N-methyl-, N-benzyl- and N-phenyl-amides (1a-c) and (2a-c) derived from picolinic and isonicotinic acids by BunLi in THF leading to the corresponding bis(N- and 3-)lithiated amides (3a-c) and (4a-c), are described.The N-phenylamides (anilides) (1c) and (2c), in comparison with the other aliphatic derivatives, demonstrate greater abilities to direct ortho lithiation at the 3-position of the pyridine ring, and give with very good yields bis(N- and 3-)lithiated anilides (3c) and (4c), respectively.The N-benzylamides (1b) and (2b) are ortho metallated under kinetic control at -78 deg C to form the bis(N- and 3-)lithiated benzylamides (3b) and (4b), but the organometallic intermediates rearrange at room temperature to give the thermodynamically more stable bis(N- and α-)lithiated amides (3g) and (4g) (benzyl-type anions).The generated carbanions (3c), (4c), (3g) and (4g) were trapped by a variety of electrophiles (e.g. alkyl halides and aldehydes).The synthesis of furopyridin-3(1H)-one (18) and furopyridin-(3H)-one (19) is included.
- Epsztajn, Jan,Bieniek, Adam,Plotka, Mieczyslaw W.
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p. 442 - 474
(2007/10/02)
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