Highly diastereo- and enantioselective allylboration of aldehydes using α-substituted allyl/crotyl pinacol boronic esters via in situ generated borinic esters
| Autor: | Varinder K. Aggarwal, Christine L. Willis, Helen K. Scott, Jack L.-Y. Chen, Matthew J. Hesse |
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| Rok vydání: | 2013 |
| Předmět: |
inorganic chemicals
Boron Compounds Molecular Conformation BORANES Stereoisomerism Boranes 010402 general chemistry 01 natural sciences Biochemistry ALLYL Catalysis BETA-METHYLHOMOALLYL ALCOHOLS BCS and TECS CDTs chemistry.chemical_compound Crotyl PURE ALLYLBORONIC ESTERS Colloid and Surface Chemistry Organic chemistry GRIGNARD-REAGENTS ASYMMETRIC-SYNTHESIS Alkyl ENANTIOMERICALLY PURE chemistry.chemical_classification Aldehydes 010405 organic chemistry Pinacol Enantioselective synthesis Esters HOMOALLYLIC ALCOHOLS General Chemistry Boronic Acids 0104 chemical sciences STEREOSELECTIVE-SYNTHESIS chemistry HIGH OPTICAL PURITY Alkoxide Selectivity |
| Zdroj: | Chen, J L-Y, Scott, H K, Hesse, M J, Willis, C L & Aggarwal, V K 2013, ' Highly Diastereo-and Enantioselective Allylboration of Aldehydes using alpha-Substituted Allyl/Crotyl Pinacol Boronic Esters via in Situ Generated Borinic Esters ', Journal of the American Chemical Society, vol. 135, no. 14, pp. 5316-5319 . https://doi.org/10.1021/ja401564z |
| ISSN: | 1520-5126 |
| DOI: | 10.1021/ja401564z |
| Popis: | Readily available, alpha-substituted allyl/crotyl pinacol boronic esters often give low E/Z selectivity (with Z favored) in reactions with aldehydes. We found that addition of nBuLi to the pinacol boronic ester followed by trapping of the alkoxide with TFAA leads to an intermediate allyl borinic ester which undergoes allylboration with very high E selectivity. The substrate scope includes primary to tertiary alkyl alpha-substituents, crotyl substrates, and the previously unreported beta-methallyl pinacol boronic esters. The latter give very high Z selectivity under standard conditions which is completely reversed to high E selectivity under the new conditions. Monitoring the reaction by B-11 NMR confirmed that the reaction proceeds through a borinic ester intermediate. |
| Databáze: | OpenAIRE |
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