Unusual diastereoselective reduction of 2-propionyl-3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene to the corresponding alcohol by BH3·Me2S. X-Ray diffraction and DFT study

Abstract

It has been found that BH₃·Me₂S reduces stereoselectively 2-propionyl-3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene 1 to the corresponding alcohol 2. The configuration (S,S_P)/(R,R_P) of 2 has been determined by X-ray diffraction study of the bis-W(CO)₅ complex (3) of 2. The stereochemical outcome of this reaction has been explained assuming an exo-attack of borane at the s-trans conformation of 1. X-Ray diffraction study and DFT calculations confirmed greater thermodynamic stability of this conformation.