Coupling of Alkynyl(2,4,6‐tri‐<i>tert</i>‐butylphenyl)phosphanes with Cuprous Chloride

Abstract

Abstract Coupling of alkynyl(2,4,6‐tri‐ tert ‐butylphenyl)phosphanes 2 with n ‐butyllithium and cuprous chloride gives 3,4‐diphospha‐1,5‐hexadiynes 3 or cuprous chloride complexes 8 of 3,4‐bis(phosphinidene)cyclobutenes 5 , depending on the bulkiness of the substituent at the triple bond. The exclusive formation of racemic 3,4‐diphospha‐1,5‐hexadiynes 3 , which was proven by 31 P‐ and 13 C‐NMR spectroscopy, explains the stereoselective rearrangement to only symmetrical cyclobutenes 5 .