- Gold Catalysis Meets Materials Science – A New Approach to π-Extended Indolocarbazoles
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Herein we describe a modular, convergent synthesis of substituted benzo[a]benzo[6,7]-indolo[2,3-h]carbazoles (BBICZs) using a bidirectional gold-catalyzed cyclization reaction as a key step. A building block strategy enabled the easy variation of substituents at different positions of the core structure and a general analysis of substitution effects on the materials properties of the target compounds. All BBICZs were fully characterized and their optical and electronic properties were studied experimentally as well as by computational methods. Organic thin-film transistors based on eight selected derivatives were fabricated by vacuum deposition and charge-carrier mobilities up to 1 cm2/Vs were measured. (Figure presented.).
- Hendrich, Christoph M.,Bongartz, Lukas M.,Hoffmann, Marvin T.,Zschieschang, Ute,Borchert, James W.,Sauter, Désirée,Kr?mer, Petra,Rominger, Frank,Mulks, Florian F.,Rudolph, Matthias,Dreuw, Andreas,Klauk, Hagen,Hashmi, A. Stephen K.
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supporting information
p. 549 - 557
(2020/12/07)
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- Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds
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The isolation and reactivities of two pentacoordinated phosphorus–tetracoordinated boron bonded compounds were explored. A highly Lewis acidic boron reagent and electron-withdrawing ligand system were required to form the pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl-trihydroborate, gave a THF stabilised phosphoranyl-borane intermediate upon a single hydride abstraction in THF. This compound could undergo a unique rearrangement, which involved a two-fold ring expansion, to give a fused bicyclic compound or it could act as a mono-hydroboration reagent. The hydroboration reactivity of the intermediate was found to be higher towards alkynes vs. alkenes, with good to moderate regioselectivity towards the terminal carbon. The second compound, a phosphoranyl-triarylborate, was found to have different reactivity as it was highly stable towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure.
- Havare, Nizam,Kano, Naokazu,Morokuma, Keiji,O'Brien, Nathan J.,Ramozzi, Romain,Uematsu, Ryohei
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- A Protocol for Direct Stereospecific Amination of Primary, Secondary, and Tertiary Alkylboronic Esters
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The direct, stereospecific amination of alkylboronic and borinic esters can be conducted by treatment of the organoboron compound with methoxyamine and potassium tert -butoxide. In addition to being stereospecific, this process also enables the direct amination of tertiary boronic esters in an efficient fashion.
- Edelstein, Emma K.,Grote, Andrea C.,Palkowitz, Maximilian D.,Morken, James P.
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supporting information
p. 1749 - 1752
(2018/06/26)
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- FUNCTIONALIZED PRIMARY ALKYLTRIFLUOROBORATE SALTS AND METHOD FOR MAKING THE SAME
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The invention provides methods for preparing boronic acids, for example, primary alkyl or alkenyl boronic acids, and alkali metal alkyl trifluoro borate salts, as described herein, wherein the primary alkyl boronic acids and the potassium alkyl trifluoroborate salts can contain one or more unprotected functional groups.
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- Amino acid-promoted C-H alkylation with alkylboronic acids using a removable directing group
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Palladium-catalyzed C-H alkylation reaction with alkylboronic acids has successfully been developed using a removable pyridyldiisopropylsilyl directing group. The amino acid played a crucial role as a ligand in the reaction. The alkylation protocol is also applicable to the coupling of C(sp3)-H bonds with alkylboronic acids.
- Zhang, Yanghui,Zhang, Yu,Jiang, Hang,Chen, Dushen
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supporting information
p. 4585 - 4589
(2016/06/09)
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- SYNTHESIS OF BORONIC ESTERS AND BORONIC ACIDS USING GRIGNARD REAGENTS
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Boronic esters and boronic acids are synthesized at ambient temperature in an ethereal solvent by the reaction of Grignard reagents with a boron-containing substrate. The boron-containing substrate may be a boronic ester such as pinacolborane, neopentylglycolborane, or a dialkylaminoborane compound such as diisopropylaminoborane. The Grignard reagents may be preformed or generated from an alkyl, alkenyl, aryl, arylalkyl, heteroaryl, vinyl, or allyl halide compound and Mg°. When the boron-containing substrate is a boronic ester, the reactions generally proceed at room temperature without added base in about 1 to 3 hours to form a boronic ester compound. When the boron-containing substrate is a dialkylaminoborane compound, the reactions generally proceed to completion at 0°C in about 1 hour to form a boronic acid compound.
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Paragraph 0102-0103; 0112
(2013/03/26)
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- Reaction of grignard reagents with diisopropylaminoborane. Synthesis of alkyl, aryl, heteroaryl and allyl boronic acids from organo(diisopropyl)- aminoborane by a simple hydrolysis
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Diisopropylaminoborane (BH2-N(iPr)2) is prepared by reacting lithium diisopropylaminoborohydride (iPr-LAB) with trimethylsilyl chloride (TMSCl). Aliphatic, aromatic, and heteroaromatic (diisopropylamino) boranes are readily synthesiz
- Bailey, Christopher L.,Murphy, Chris L.,Clary, Jacob W.,Eagon, Scott,Gould, Naomi,Singaram, Bakthan
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p. 331 - 341
(2013/08/23)
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- Aryl trihydroxyborates: Easily isolated discrete species convenient for direct application in coupling reactions
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A conceptually and practically simple alternative approach to the use of arylboron species as the organometallic component in cross-coupling processes is described whereby trihydroxyborate salts are isolated and directly employed. The protocol derives practical benefit from the ease and convenience of the isolation and subsequent use of the discrete borate salts, eliminates the need for additional base, and aids the use of correct reaction stoichiometry.
- Cammidge, Andrew N.,Goddard, Victoria H. M.,Gopee, Hemant,Harrison, Nicola L.,Hughes, David L.,Schubert, Christopher J.,Sutton, Benjamin M.,Watts, Gary L.,Whitehead, Andrew J.
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p. 4071 - 4074
(2007/10/03)
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- Total synthesis of (-)-microcarpalide, a novel microfilament disrupting metabolite
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The stereoselective total synthesis of (-)-microcarpalide, a recently discovered 10-membered lactone of fungal origin displaying a remarkable disrupting action on actin microfilaments, was accomplished by using ring-closing metathesis (RCM) as the key step for the formation of the medium-sized ring. The diene ester required for the macrocyclization reaction was assembled via DCC-mediated esterification of two suitable partners, each bearing a terminal alkene group. The alcohol fragment was synthesized from n-bromohexane through a seven-step sequence entailing two consecutive stereoselective homologations of chiral boronic esters as strategic transformations for the sequential insertion of the two stereocentres with the final S absolute configuration, using (+)-pinanediol as the chiral director; final elaboration to the desired C11 framework envisaged treatment with an allyl Grignard reagent and oxidative cleavage of the boronic scaffold. In contrast, the acidic fragment was prepared in ten steps from D-tartaric acid, whose C4 backbone was elongated to the required C7 skeleton by means of two distinct Swern-Wittig oxidation-homologation sequences.
- Davoli, Paolo,Spaggiari, Alberto,Castagnetti, Luca,Prati, Fabio
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- P1 Phenethyl peptide boronic acid inhibitors of HCV NS3 protease
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A series of peptide boronic acids containing extended, hydrophobic P1 residues was prepared to probe the shallow, hydrophobic S1 region of HCV NS3 protease. The p-trifluoromethylphenethyl P1 substituent was identified as optimal with respect to inhibitor potency for NS3 and selectivity against elastase and chymotrypsin.
- Priestley,De Lucca, Indawati,Ghavimi, Bahman,Erickson-Viitanen, Susan,Decicco, Carl P.
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p. 3199 - 3202
(2007/10/03)
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- Organoboranes. 30. Convenient procedures for the synthesis of alkyl- and alkenylboronic acids and esters
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Alkyl- and alkenyldibromoborane-dimethyl sulfide complexes, readily obtained by the hydroboration of alkenes and alkynes with dibromoborane-dimethyl sulfide (HBBr2-SMe2), react with water, giving the corresponding boronic acids, and with alcohols and glycols to give the corresponding esters. Various procedures have been developed for the preparation of boronic esters with primary and secondary alcohols, glycols, and tertiary alcohols. Boronic acids react with primary and secondary alcohols reversibly to form the corresponding esters. The equilibrium may be conveniently displaced in favor of ester by carrying out the reaction in pentane, from which the water component separates. This procedure does away with the necessity of azeotrope distillation of a ternary mixture, extensively used previously for the esterification of boronic acids.
- Brown, Herbert C.,Bhat,Somayaji, Vishwanatha
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p. 1311 - 1316
(2008/10/08)
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