Synthesis of enantioenriched tertiary boronic esters from secondary allylic carbamates. Application to the synthesis of C30 botryococcene

Alexander P Pulis; Varinder K Aggarwal

doi:10.1021/ja303022d

Synthesis of enantioenriched tertiary boronic esters from secondary allylic carbamates. Application to the synthesis of C30 botryococcene

J Am Chem Soc. 2012 May 2;134(17):7570-4. doi: 10.1021/ja303022d. Epub 2012 Apr 23.

Authors

Alexander P Pulis¹, Varinder K Aggarwal

Affiliation

¹ School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom.

PMID: 22524150
DOI: 10.1021/ja303022d

Abstract

Enantioenriched secondary allylic carbamates have been deprotonated with sBuLi and reacted with boronic esters. In contrast to other electrophiles, high α-selectivity was observed and the boronate complexes were formed with almost complete retention of stereochemistry. The boronate complexes underwent a stereospecific 1,2-migration leading to tertiary allylic boronic esters with high er (>98:2). The scope of the reaction has been explored and found to embrace a broad range of both allylic carbamates and boronic esters. The methodology has been applied to an eight-step, stereoselective synthesis of each of the diastereoisomers of C30 botryococcene.