Highly Selective Allylborations of Aldehydes Using α,α-Disubstituted Allylic Pinacol Boronic Esters

• Published in: Angewandte Chemie International Edition Vol. 53; no. 24; pp. 6145 - 6149
• Main Authors: Hesse, Matthew J., Essafi, Stéphanie, Watson, Charlotte G., Harvey, Jeremy N., Hirst, David, Willis, Christine L., Aggarwal, Varinder K.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 10.06.2014; WILEY‐VCH Verlag; Wiley
• Subjects: Aldehydes - chemistry; alkenes; Alkenes - chemical synthesis; allylation; asymmetric synthesis; Boron - chemistry; Chemistry; Chemistry, Multidisciplinary; CC coupling; Esters - chemistry; Molecular Structure; Physical Sciences; Science & Technology; synthetic methods; C-C coupling; REAGENTS; ENANTIOSELECTIVE SYNTHESIS; HOMOALLYLIC ALCOHOLS; STEREOCHEMISTRY; alkenes; TETRASUBSTITUTED ALKENES; ALKYNES; TERTIARY; asymmetric synthesis; DIASTEREOSELECTIVE SYNTHESIS; OLEFINS; STEREOSELECTIVE-SYNTHESIS; allylation; synthetic methods; CC coupling
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201402995

α,α‐Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti‐Z‐selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β‐borylated allylic boronic esters gave fully substituted alkenes bearing a boronic ester which underwent further cross‐coupling enabling a highly modular and stereoselective approach to the synthesis of diaryl tetrasubstituted alkenes. Computational analysis revealed the origin of the remarkable selectivity observed. Asymmetric CC coupling: α,α‐Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti‐Z‐selectivity (see scheme). The scope of the reaction includes both acyclic and cyclic allylic boronic esters. β‐Borylated allylic boronic esters gave fully substituted vinyl boronates suitable for further cross‐coupling.