Three-Component [1 + 1 + 1] Cyclopropanation with Ruthenium(II)

Abstract

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey–Chaykovsky, Simmons–Smith, and metal-catalyzed carbene attack on olefins. Under the current protocol, various alcohols and esters are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. Twenty-two examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multistep, linear routes that proceed with overall low yields and poor control of stereochemistry. Commercially available Ru(II) dehydrogenation catalysts, that were recently developed for the dehydrogenative synthesis of esters and amides from alcohol and amine substrates, were used in the reaction, with the best catalyst showing excellen...