Cyclopropylmethyl Boronic Esters as General Reagents in Transition-Metal Catalyzed Homoallylation Reactions

Herein we disclose the use of cyclopropylmethyl boronates as general reagents in Negishi-type homoallylation reactions. This strategy provides a novel approach to generate enantioenriched homoallyl-Zn species through boron-to-zinc transmetalation. Subsequent sp²-sp³ cross-coupling offers a platform for the preparation of arenes, ketones, and 1,5-dienes containing a chiral homoallylic scaffold. The method has been applied to the late-stage functionalization of known drugs and the preparation of precursors of biologically relevant compounds. Mechanistic experiments and DFT calculations provide insight into the transmetalation/ring-opening sequence.