Highly enantioselective synthesis of trifluoromethyl cyclopropanes by using Ru(ii)-Pheox catalysts.

An asymmetric synthesis of various trifluoromethyl cyclopropanes from olefins, such as vinyl ferrocene, vinyl ethers, vinyl amines, vinyl carbamates and dienes, was achieved by using Ru(ii)-Pheox catalysts. This catalytic system can function at a low catalyst loading (3 mol%) compared with those reported previously, and the desired cyclopropane products are obtained in high yields with excellent diastereoselectivity (up to >99 : 1) and enantioselectivity (up to 97% ee).

Highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by Ru(ii)-Pheox complexes.

A highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by chiral Ru(ii)-Pheox complexes was developed to give chiral cyclopropyl sulfones in high yields (up to 99%) with excellent trans-selectivity and enantioselectivity (up to 98% ee).

Williamson Ether Synthesis with Phenols at a Tertiary Stereogenic Carbon: Formal Enantioselective Phenoxylation of β-Keto Esters.

The enantioselective formation of α-aryloxy-β-keto esters is described for the first time. Lewis acid catalyzed enantioselective chlorination of β-keto esters and subsequent SN 2 reactions with phenols yielded α-aryloxy-β-keto esters with up to 96% ee. Favorskii rearrangement of α-chloro-β-keto esters was also found to give 1,2-diesters with slightly reduced enantiopurity.