Anion-Mediated, Stereospecific Synthesis of Secondary and Tertiary Cyclopropylboronates from Chiral Epoxides and <i>gem</i>-Diborylalkanes

Abstract

We report a transition-metal-free deborylative cyclizationapproachto synthesize enantioenriched secondary and tertiary cyclopropylboronatesusing gamma-phosphate-containing gem-diborylalkanesderived from chiral epoxides and gem-diborylalkanes.Our method enables the synthesis of a broad range of enantioenrichedsecondary and tertiary cyclopropylboronates in good yields with excellentstereospecificity. We demonstrate the versatility of our approachby performing a gram-scale reaction. We also show that the enantioenrichedtertiary cyclopropylboronates can be transformed into a wide arrayof enantioenriched cyclopropane derivatives in a stereospecific boron-grouptransformation.