Mechanistic studies on the course of a σ-but-3-enyl- to 1–3-η-but-2-enyl-nickel transformation

Abstract

σ-But-3-enyl-π-cyclopentadienyltriphenylphosphinenickel (10b) is converted into trans-1–3-η-but-2-enyl-π-cyclopentadienylnickel on thermolysis at 75° or photolysis through Pyrex in benzene solution. By employing (10b) labelled with deuterium in the 1- or 4-position of the butenyl group the course of rearrangement was deduced and showed that in thermolysis C-1 and -4 became equivalent but that the photochemical reaction was regioselective, and involved a predominant [1,3] hydrogen shift. Mechanistic implications are discussed. Synthesis and reactions of the cyclopropyl and cyclobutyl analogues of (10b) and attempts to form the cyclopropylmethyl analogue are reported.