Diastereoselective Borocyclopropanation of Allylic Ethers Using a Boromethylzinc Carbenoid

A borocyclopropanation of (E)- and (Z)-allylic ethers and styrene
derivatives via the Simmons–Smith
reaction using a novel boromethylzinc carbenoid is described. The
carbenoid precursor is prepared via a 3-step sequence from inexpensive
and commercially available starting materials. This methodology allows
for the preparation of 1,2,3-substituted borocyclopropanes in high
yields and diastereoselectivities. Several postfunctionalization reactions
were also performed to illustrate the versatility of these building
blocks.