A new optically active secondary diphosphine—its use for the improved synthesis of (R,R)-1,2-bis(boranato(tert-butyl)methylphosphino)ethane

(S,S)-1,2-Bis(boranato(tert-butyl)phosphino)ethane has been synthesized efficiently and in excellent enantioselectivity. This secondary diphosphine serves as the starting material for an elegant preparation of (R,R)-1,2-bis(boranato(tert-butyl)methylphosphino)ethane, known as (R,R)-t-Bu-BisP*–borane.