Intramolecular Chromium(II)-Catalyzed Pinacol Cross Coupling of 2-Methylene-α,ω-dicarbonyls

Abstract

Using only 10% of CrCl2 as catalyst, manganese-powder as reducing agent and TMSCl as scavenger, 2-methylene-α,ω-di­aldehydes and -ketones can be coupled to form cyclic diols dia­stereoselectively. The diastereomeric excess strongly depends on the ring size and the substituents of the ω-carbonyl group. The greater the ring size the higher diastereoselectivities are observed. In all cases cis-diols are preferentially formed.