- Copper(I)-catalyzed enantioselective synthesis of α-chiral linear or carbocyclic (e)-(γ-alkoxyallyl)boronates
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A new method has been developed for the catalytic asymmetric synthesis of α-chiral linear or carbocyclic (γ-alkoxyallyl)boronates via the copper(I)-catalyzed γ-boryl substitution of allyl acetals. This reaction afforded the products in high yields with ex
- Yamamoto, Eiji,Takenouchi, Yuta,Ozaki, Taichi,Miya, Takanori,Ito, Hajime
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- SECONDARY METABOLITES BY CHEMICAL SCREENING - 13. ENANTIOSELECTIVE SYNTHESIS OF δ-LACTONES FROM STREPTENOL A, A CHIRAL BUILDING BLOCK FROM STREPTOMYCES
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The enantioselective synthesis of all four stereoisomers of the secondary metabolite 3-hydroxy-5-decanolide (4a) from Cephalosporium recifei and both enatiomers of massoialactone (5a) by starting from one chiral building block, streptenol A (1a), a secondary metabolite from Streptomyces sp., is described.The key steps of the reaction sequence involve diastereoselective reduction of 1a to syn- or anti-triol 2a and 2b and the regioselective oxidation of the primary hydroxyl group.This reaction furnishes in one step the δ-lactones 3a and 3b and requires no protecting group.
- Romeyke, Yvonne,Keller, Martin,Kluge, Heinz,Grabley, Susanne,Hammann, Peter
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- Organocatalytic enantioselective approach to the synthesis of verbalactone and (R)-massoialactone
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The organocatalytic enantioselective synthesis of verbalactone and (R)-massoialactone is described. The requisite stereogenic centers of the target molecules were constructed using l-proline-catalyzed -aminoxylation and Horner-Wadsworth-Emmons (HWE) olefination. Yamaguchi macrolactonization and ring-closing metathesis were employed as key steps in the syntheses. Georg Thieme Verlag Stuttgart - New York.
- Harbindu, Anand,Kumar, Pradeep
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- One-pot diastereoselective preparation of α,β-unsaturated-γ-silylated-δ-lactones: Application towards natural compounds
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Rearrangement of silylated vinyloxiranes into highly functionalized α-silylated-β,γ-unsaturated aldehydes occurs with total chirality transfer and retention of double bond configuration under Pd(0) catalysis. We show that this reaction is a versatile tool in the field of total stereoselective synthesis: enantiomerically pure lactones are obtained. The pheromone 6-n-undecyltetrahydro-2-pyrone 2 and massoilactone, 5-hydroxy-2-decenoic acid lactone 3, are synthesized. We describe herein a novel highly diastereoselective route to α,β-unsaturated-γ-silylated-δ-substituted-δ-lact ones 1.
- Marion,Le Fol,Courillon,Malacria
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- General, Highly Selective Synthesis of 1,3- and 1,4-Difunctionalized Building Blocks by Regiodivergent Epoxide Opening
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We describe a regiodivergent epoxide opening (REO) featuring a catalyst-controlled synthesis of enantiomerically and diastereomerically highly enriched or pure syn- and anti- 1,3- and 1,4-difunctionalized building blocks from a common epoxide precursor. The REO is attractive for natural product synthesis and as a branching reaction for diversity-oriented synthesis with epoxides.
- Funken, Nico,Mühlhaus, Felix,Gans?uer, Andreas
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- Enzyme catalysed lactonization of 3,5 dihydroxy esters: Enantioselective synthesis of naturally occurring 3-hydroxy-5-decanolide, (-)-massoialactone, and 3-hydroxy-5-icosanolide
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Synthesis of optically active (+)-3-hydroxy-5-decanolide, (-)-massoialactone and of the recently isolated 3-hydroxy-5-icosanolide was achieved by enzyme-catalysed lactonization of racemic 3,5 dihydroxy esters with PPL in dry Et2O. Ees vary from 86% up to >98%.
- Bonini,Pucci,Racioppi,Viggiani
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- Preparation method of (R)-(-)-massoialactone
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The invention discloses a preparation method of (R)-(-)-massoialactone. The preparation method includes the following steps: in a solvent, under the action of a copper salt, an alkali and a ligand, beta,gamma-unsaturated ester and n-hexanal are subjected to a reaction shown in the specification to obtain (R)-(-)-massoalactrone; the copper salt is Cu(CH3CN)4PF6 or the alkali is Barton's Base, alkali metal tert-butanol salt or the ligand is (R,R)-Ph-BPE or (S)-DTBM-SEGPHOS. (R)-(-)-massoialactone can be obtained by one-step reaction with high yield and ee value; compared with other methods in the prior art, the method has many advantages, such as simple route, easy access to raw materials, mild conditions and the like, and has obvious advantages.
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Paragraph 0057; 0059-0062
(2019/12/25)
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- Rationally Designed Chiral Synthons Enabling Asymmetric Z- and E-Selective Vinylogous Aldol Reactions of Aldehydes
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In a conceptually different approach, highly stereoselective 2-oxonia-Cope rearrangement reactions between rationally designed nonracemic vinylogous aldolation synthons and aldehydes are described to provide δ-hydroxy-α,β-unsaturated esters with excellent
- Padarti, Akhil,Han, Hyunsoo
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supporting information
p. 1448 - 1452
(2018/03/09)
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- Enzyme-mediated enantioselective hydrolysis of 1,2-diol monotosylate derivatives bearing an unsaturated substituent
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We have succeeded in the easy preparation of optically active 1,2-diol monotosylates bearing an unsaturated substituent via enzymatic hydrolysis. Lipase PS quickly catalyzes the hydrolyses of 2-acetoxybut-3-enyl tosylate, which has a double bond, and 2-acetoxybut-3-ynyl tosylate, which has a triple bond, with excellent enantioselectivity to afford the corresponding optically active compounds. The reaction is also applicable to acetates with a longer chain, which has a double bond at the terminus. To demonstrate the applicability of this method, enantiomerically pure (R)-massoialactone, a natural coconut flavor, has been synthesized from racemic 2-acetoxypent-4-enyl tosylate in several steps. Furthermore, the enzyme can recognize the stereochemistry of olefins, and the (Z)-alkenyl structure is more suitable for the enantioselective hydrolysis than the (E)-isomer.
- Matsumoto,Oohana,Hashimoto,Usuda,Shimoda,Ohshima,Suzuki,Togawa
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p. 3981 - 3988
(2018/06/15)
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- Asymmetric Synthesis of α,β-Unsaturated δ-Lactones through Copper(I)-Catalyzed Direct Vinylogous Aldol Reaction
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A simple methodology for the asymmetric synthesis of chiral α,β-unsaturated δ-lactones was achieved by copper(I)-catalyzed direct vinylogous aldol reaction (DVAR) of β,γ-unsaturated esters and various aldehydes, including aromatic aldehydes, heteroaromatic aldehydes, α,β-unsaturated aldehydes, and aliphatic aldehydes. For aromatic and heteroaromatic aldehydes, a one-pot reaction consisting of DVAR, isomerization of the unsaturated carbon-carbon double bond from (E)-form to (Z)-form, and subsequent intramolecular transesterification was required to get the lactones in moderate to high yields with high enantioselectivity. For α,β-unsaturated and aliphatic aldehydes, the DVAR proceeded directly to afford the lactones in moderate yields with high enantioselectivity. In the DVAR, various functional groups were well tolerated. Moreover, the methodology was nicely applicable to the aldehyde group distributed in natural products, derivatives of natural product, and derivatives of drug molecules (atomoxetine and naproxen). The mechanism studies revealed that α-addition was reversible and not favored, which accounted for the excellent regioselectivity in the DVAR. The copper(I)-dienolate species generated through deprotonation was proposed to form an equilibrium with an allylcopper(I) species, which reacted with aldehydes to afford the DVAR products through a catalytic asymmetric allylation of aldehydes. Finally, the robustness of the present reaction was demonstrated by a gram-scale reaction, and the utility of the present methodology was showcased by the formal asymmetric synthesis of ezetimibe and fostriecin.
- Zhang, Hai-Jun,Yin, Liang
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supporting information
p. 12270 - 12279
(2018/09/25)
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- PPARS AGONIST ACTIVITY ENHANCING DRUG
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According to the present invention, PPARs agonist activity is enhanced in order to improve metabolic syndrome, hyperlipidemia, and diabetes. Provided is a compound having a lactone structure comprising formula (9).
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Paragraph 0042-0043; 0044
(2015/03/03)
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- Synthesis and evaluation of (-)-Massoialactone and analogues as potential anticancer and anti-inflammatory agents
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(-)-Massoialactone, an α,β-unsaturated δ-lactone isolated from Cryptocarya massoia, and five analogues were synthesized and their antiproliferative and anti-inflammatory activities were evaluated. The lactones were able to mimic the "core" functional grou
- Barros, Maria E.S.B.,Freitas, Juliano C.R.,Oliveira, Juliana M.,Da Cruz, Carlos H.B.,Da Silva, Paulo B.N.,De Araújo, Larissa C.C.,Milit?o, Gardenia C.G.,Da Silva, Teresinha G.,Oliveira, Roberta A.,Menezes, Paulo H.
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p. 291 - 300
(2014/03/21)
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- Antimicrobial activities of novel mannosyl lipids isolated from the biocontrol fungus simplicillium lamellicola BCP against phytopathogenic bacteria
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The antagonistic fungus Simplicillium lamellicola BCP has been developed as a microbial biopesticide that effectively controls the development of various plant diseases caused by both pathogenic bacteria and pathogenic fungi. Antibacterial bioassay-directed fractionation was used to isolate mannosyl lipids from S. lamellicola BCP, and the structures of these compounds were elucidated using spectral analysis and chemical degradation. Three novel mannosyl lipids were characterized and identified as halymecins F and G and (3R,5R)-3-O-β-d-mannosyl-3,5-dihydrodecanoic acid. Massoia lactone and (3R, 5R)-3-hydroxydecan-5-olide were also isolated from S. lamellicola BCP. The three novel compounds inhibited the growth of the majority of phytopathogenic bacteria that were tested, and halymecin F displayed the strongest antibacterial activity. Agrobacterium tumefaciens was the most sensitive to the three novel compounds, with IC50 values ranging from 1.58 to 24.8 μg/mL. The ethyl acetate extract of the fermentation broth from the antagonistic fungus effectively reduced the bacterial wilt caused by Ralstonia solanacearum on tomato seedlings. These results indicate that S. lamellicola BCP suppresses the development of plant bacterial diseases through the production of antibacterial metabolites.
- Le Dang, Quang,Shin, Teak Soo,Park, Myung Soo,Choi, Yong Ho,Choi, Gyung Ja,Jang, Kyoung Soo,Kim, In Seon,Kim, Jin-Cheol
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p. 3363 - 3370
(2014/05/06)
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- Methyl (5R)-5-hydroxy-3-methylidenedecanoate as a promising building block in asymmetric syntheses of bioactive natural compounds
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Simple and efficient asymmetric syntheses of several lactones with the use of methyl (5R)-5-hydroxy-3-methylidenedecanoate as a polyfunctional building block are described.
- Mineeva
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p. 979 - 985
(2013/09/02)
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- Enantiomerically pure allylboronic esters as versatile reagents in the enantioselective synthesis of dihydro-α-pyrone-containing natural products
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A short and efficient enantio- and diastereoselective synthesis of different representatives from the class of dihydro-α-pyrone natural products, including both enantiomers of goniothalamin, massoia lactone, parasorbic acid, and some derivatives is presented. It is based on the application of enantiopure α-chiral allylboronic esters in allyl additions. Georg Thieme Verlag Stuttgart New York.
- Bartlett, Sean,Boese, Dietrich,Ghori, Daniel,Mechsner, Bastian,Pietruszka, Joerg
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p. 1106 - 1114
(2013/05/21)
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- Asymmetric synthesis of (-)-(R)-massoia lactone, (R)-δ-decalactone, and (+)-(3R,5R)-3-hydroxydecano-5-lactone. Formal synthesis of Verbalactone
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A simple and efficient procedure for the asymmetric synthesis of (-)-(R)-massoia lactone, (R)-δ-decalactone, and (+)-(3R,5R)-3-hydroxy-1,5- decanolide is described. Verbalactone was synthesized using Heck allylation at the key stage of construction of the carbon skeleton.
- Mineeva
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p. 977 - 981
(2012/11/07)
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- Modular synthesis of optically active lactones by Ru-catalyzed asymmetric allylic carboxylation and ring-closing metathesis reaction
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A new synthetic route to optically active unsaturated γ- and δ-lactones has been demonstrated via asymmetric allylic carboxylation with a planar-chiral Cp′Ru catalyst and ring-closing metathesis reaction with a Grubbs II catalyst, and successfully applied to the enantioselective synthesis of (R)-(-)-massoialactone. The Royal Society of Chemistry 2012.
- Takii, Koichiro,Kanbayashi, Naoya,Onitsuka, Kiyotaka
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supporting information; experimental part
p. 3872 - 3874
(2012/05/19)
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- Synthesis of substituted α,β-unsaturated δ-lactones from vinyl tellurides
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A new approach for the synthesis of α,β-unsaturated δ-lactones, a unit present in many natural products with interesting biological activities is described. The approach was based on the use of a vinyl telluride, and it is complementary to the methods usi
- Oliveira, Juliana M.,R. Freitas, Juliano C.,Comasseto, Jo?o Valdir,Menezes, Paulo Henrique
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p. 3003 - 3009
(2011/04/27)
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- A facile approach towards synthesis of verbalactone and biologically active δ-lactones using d-glucose
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A general synthetic approach has been developed for the asymmetric synthesis of chiral δ-lactones and verbalactone using d-glucose. The key intermediate used in this approach was α-diazoketone.
- Garg, Ashish,Singh, Vinod K.
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experimental part
p. 8677 - 8682
(2010/01/06)
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- Chiral a-substituted allylboronates in a one-pot three-component asymmetric allylic alkylation/carbonyl allylation reaction sequence -Applications to the syntheses of (+)-(3R,5R)-3-hydroxy-5-decanolide and (-)-massoialactone
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The use of different organomagnesium reagents in the copper-catalyzed allylic alkylation of 3-chloropropenyl with chiral phosphoramidite ligands produces the desired a-substituted allylic boronate reagents in high and with modest to high enantioselectivities (up to 96% ee). The size of the incoming alkyl substituent the organomagnesium reagent was found to impact the yield and selectivity of the allylic alkylation. A one-pot for the preparation of these chiral allylic boronates followed by a Lewis acid (BF3) catalyzed addition to aldehydes the desired allylboration products, homoallylic secondary alcohols, in good yields and very high diastereoselectivity.three-component reaction methodology was applied to the syntheses of two lactone-containing natural , (-)-massoialactone and (+)-(3R,5R)-3-hydroxy-5-decanolide. The key step of these syntheses involved the pot enantioselective copper-catalyzed allylic alkylation/allylboration reaction with a benzylic aldehyde, and the desired product in 87% yield, 92% e,and high E/Z selectivity in a ratio of 22:1. Remarkably, the alkylation step of this sequential reaction was performed with a low catalyst loading of 2 mol% on a scale >15 mmol that can provide multiple grams of the three-component product.
- Carosi, Lisa,Hall, Dennis G.
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experimental part
p. 650 - 661
(2009/10/30)
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- Synthesis of (+)-(3R,5R)-3-hydroxy-5-decanolide and massoialactone, and formal synthesis of verbalactone
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Total synthesis of (3R, 5R)-(+)-3-hydroxy-5-decanolide (1) and massoialactone (2), and formal synthesis of verbalactone (3), have been reported. Copyright Taylor & Francis Group, LLC.
- Sabitha, Gowravaram,Bhaskar,Yadav
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p. 3129 - 3141
(2008/12/23)
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- Versatile approach for the asymmetric synthesis of (R)- and (S)-massoialactones
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A general synthetic approach to both enantiomers, (R)- and (S)-massoialactones, has been devised from commercially available (S)-butane-1,2,4-triol. Copyright Taylor & Francis Group, LLC.
- Sabitha, Gowravaram,Gopal,Yadav
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p. 1495 - 1502
(2008/02/02)
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- Synthesis of enantiopure (R)-(-)-massoialactone through ruthenium-SYNPHOS asymmetric hydrogenation
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Total synthesis of enantiopure (R)-(-)-massoialactone was achieved. The key step includes the asymmetric hydrogenation of an achiral β-keto ester using a ruthenium-SYNPHOS catalyst to set the hydroxyl function in a stereocontrolled manner with excellent enantioselectivity (>99% ee). Ring closing metathesis (RCM) in the presence of Grubbs' catalyst allows the final construction of the six-membered lactone.
- Touati, Ridha,Ratovelomanana-Vidal, Virginie,Hassine, Bechir Ben,Genet, Jean-Pierre
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p. 3400 - 3405
(2007/10/03)
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- The β-lactone route to α,β-unsaturated δ-lactones. Total syntheses of (±)-goniothalamin and (-)-massoialactone
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The HF-induced translactonization of 2′-silyloxy-3-trimethylsilyl-2- oxetanones, obtained through Lewis acid-promoted [2+2] cycloaddition between β-silyloxyaldehydes and trimethylsilylsilylketene, into α,β-unsaturated δ-lactones is applied to the syntheses of (±)-goniothalamin and (-)-massoialactone.
- Fournier, Lycia,Kocienski, Philip,Pons, Jean-Marc
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p. 1659 - 1663
(2007/10/03)
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- A practical enantioselective synthesis of massoialactone via hydrolytic kinetic resolution
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An efficient enantioselective synthesis of (R)- and (S)-massoialactone has been achieved. The key steps are the hydrolytic kinetic resolution of a racemic epoxyheptane with (R,R)-(salen)-CoIIIOAc complex and ring-closing metathesis of homoallylic alcohol derived acrylate esters using Grubb's catalyst.
- Gupta, Priti,Naidu, S. Vasudeva,Kumar, Pradeep
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p. 849 - 851
(2007/10/03)
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- Synthesis of the racemate and both enantiomers of massoilactone
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A simple and efficient synthesis of (±)-massoilactone (1) as a key substance for the butter and milk flavor was accomplished from n-hexanal in only a few steps. Application of its racemic synthesis enabled natural (R)-(-)-and unnatural (S)-(+)-massoilacto
- Ishikawa, Masashi,Amaike, Masayasu,Itoh, Masamichi,Warita, Yasuhiro,Kitahara, Takeshi
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p. 2210 - 2214
(2007/10/03)
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- A new chiral route to 5- and 6-substituted hydropyran-2-ones utilizing enantiopure 4-cumyloxy-2-cyclopenten-1-one
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Starting from enantiopure 4-cumyloxy-2-cyclopenten-1-one, a route to 5- and 6-substituted hyropyran-2-ones has been developed. The method has achieved the synthesis of 4,5-cis- and 4,5-trans-5-ethyl-4-hydroxytetrahydropyran-2-ones assigned to marine natural products simplactones. A and B to disprove the former and revise the latter of the proposed structures.
- Sato, Masayuki,Nakashima, Hiromi,Hanada, Keisuke,Hayashi, Masato,Honzumi, Masatoshi,Taniguchi, Takahiko,Ogasawara, Kunio
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p. 2833 - 2837
(2007/10/03)
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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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- Asymmetric synthesis of goniothalamin, hexadecanolide, massoia lactone, and parasorbic acid via sequential allylboration-esterification ring-closing metathesis reactions
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Acrylic esters of homoallylic alcohols prepared in 92-97% ee via the asymmetric allylboration of appropriate aldehydes with B- allyldiisopinocampheylborane, when refluxed in dichloromethane in the presence of 10 mol% of Grubbs' catalyst provided the natural enantiomers of (S)-(+)-parasorbic acid, (R)-(-)-massoia lactone, and (R)-(+)goniothalamin. (S)-(-)-Hexadecanolide was prepared by hydrogenating the corresponding lactenone synthesized using the above sequence. (C) 2000 Elsevier Science Ltd.
- Ramachandran, P. Veeraraghavan,Reddy, M. Venkat Ram,Brown, Herbert C.
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p. 583 - 586
(2007/10/03)
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- Asymmetric synthesis of (S)-Massoialactone
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An asymmetric synthesis of (S)-(+)-Massoialactone is described using the Sharpless asymmetric dihydroxylation and the regiospecific nucleophilic opening of a cyclic sulfate as key steps.
- Pais, Godwin C.G.,Fernandes, Rodney A.,Kumar, Pradeep
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p. 13445 - 13450
(2007/10/03)
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- Enzyme Assisted Synthesis of Enantiomerically Pure δ-Lactones
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Both enantiomers series of a wide variety of optically pure 6-alkylated δ-lactones - saturated as well as unsaturated - were prepared via an enzyme mediated route.The key reaction step is the nucleophilic ring opening of enantiomerically pure alkyl-oxiranes, accessible via the corresponding β-hydroxythioesters which can be obtained enantiomerically pure via enzyme catalyzed kinetic resolutions.
- Haase, Bernhard,Schneider, Manfred P.
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p. 1017 - 1026
(2007/10/02)
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- An enantiospecific route to (6R)-(-)-massoialactone and (4R,6R)-(+)-4-hydroxy-6-pentylvalerolactone
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An enantiospecific route to two δ-lactone natural products, (6R)-(-)-massoialactone and (4R,6R)-(+)-4-hydroxy-6-pentylvalerolactone, has been developed by using (R)-epichlorohydrin as a chiral starting material.
- Takano,Setoh,Ogasawara
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p. 533 - 534
(2007/10/02)
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- Total Syntheses of Natural (+)-(4R,6R)-4-Hydroxy-6-pentylvalerolactone and of (-)-(6R)-Massoialactone
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An asymmetric total synthesis and hence a confirmation of the absolute configuration of naturally occurring (+)-(4R,6R)-4-hydroxy-6-pentylvalerolactone 10, a metablolite of Cephalosporium recifei, is described, starting from the yeast reduction product methyl (3R)-3-hydroxyhex-5-enoate 5.The key step is a highly trans-selective kinetic iodolactonization of the unsaturated acid 16e.Dehydration of the lactone 10 leads to natural (-)-(6R)-massoialactone 11.
- Bennett, Frank,Knight, David W.,Fenton, Garry
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p. 1543 - 1547
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF HOMOCHIRAL δ-ALKYLATED α,β-UNSATURATED δ-LACTONES
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The tert-butyl propiolate ion serves as a convenient and efficient nucleophile in boron trifluoride-catalyzed openings of homochiral, mono-substituted epoxides.The resulting tert-butyl 5-hydroxy-2-alkynoates are converted into the title compounds upon semihydrogenation followed by acid hydrolysis.Specific examples include the synthesis of parasorbic acid and massoilactone, two naturally derived lactones of the present type.The scope of the synthetic protocol is discussed.
- Hoeyer, Thomas,Kjaer, Anders,Lykkesfeldt, Jens
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p. 1042 - 1051
(2007/10/02)
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- SYNTHESIS AND UTILIZATION OF OPTICALLY ACTIVE 2-SUBSTITUTED 4-(TRIMETHYLSILYL)CYCLOPENTANONES: SYNTHESIS OF (-)-MASSOIALACTONE AND (+)-β-CUPARENONE
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Ring contraction by BF3*Et2O catalyzed epoxide rearrangement of 3-substituted 5-trimethylsilyl-2,3-epoxycyclohexanones gave the corresponding 2-substituted 4-(trimethylsilyl)cyclopentanones diastereoselectively.Synthesis of (-)-massoialactone and (+)-β-cuparenone utilizing the above transformation is also described.
- Asaoka, Morio,Hayashibe, Satoshi,Sonoda, Syuzo,Takei, Hisashi
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p. 4761 - 4764
(2007/10/02)
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- ASYMMETRIC REDUCTIONS OF PROPARGYL KETONESAN EFFECTIVE APPROACH TO THE SYNTHESIS OF OPTICALLY-ACTIVE COMPOUNDS
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Propargyl ketones are readily reduced by the asymmetric reducing agent B-3-pinanyl-9-borabicyclo-nonane (Alpine-borane).The reagent prepared from (+)-α-pinene and 9-BBN provides the R enantiomer while the S enantiomer can be obtained from (-)-α-pinene.Alternatively the S enantiomer ca be prepared from the reagent derived from 9-BBn and the benzyl ether of nopol (6,6-dimethyl-bicyclohept-2-ene-2-ethanol).The limiting factor in obtaining high enantiomeric induction is often the enantiomeric purity of the α-pinene.With 100percent enantiomerically pure α-pinene, propargyl alcohols of essentially 100percent ee can be obtained.A predictive rationalization of the transition state leading to this remarkable selection is presented.The acetylene unit of the propargyl alcohol provides a convenient handle for transformations to other useful, optically-active products.The use of propargyl alcohols for the synthesis of optically-active α- and β-substituted γ-lactones, and δ-lactones is illustrated.
- Midland, M. Mark,Tramontano, Alfonso,Kazubski, Aleksander,Graham, Richard S.,Tsai, David J. S.,Cardin, Daniel B.
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p. 1371 - 1380
(2007/10/02)
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- Enantiomerically Pure Lactones. 3. Synthesis of and Stereospecific Conjugate Additions to α,β-Unsaturated Lactones
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A general synthetic approach to both enantiomers of α,β-unsaturated lactones of general formula 1 has been devised, the first synthesis of the naturally occuring antipode of massoilactone (1b) exemplifying the approach.Interestingly, the specific rotation of massoilactone (and its enantiomer) is higher than that of the natural material isolated from formicine ants.A key step in the sequence involves chromatographic separation of rationally selected diastereomeric derivatives of racemic intermediates. Compounding the utility of an approach to optically active, type 1 lactones is the observation that conjugate additions of organometallic reagents to such lactones proceed with a high degree of stereospecificity, affording lactones of general formula 2. The conformational behavior of lactone 1a is considered as is the solvation of δ-lactones by fluoroalcoholic chiral solvating agents such as 2,2,2-trifluoro-1-(9-anthryl)ethanol (8).
- Pirkle, William H.,Adams, Paul E.
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p. 4117 - 4121
(2007/10/02)
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