Reduction of α,β-unsaturated ketones and aldehydes by tungsten–tungsten triple bonds: formation of 1,2 and 1,4 adducts as opposed to CO cleavage

Abstract

Whereas reactions between sterically unencumbered aldehydes RCHO and [W₂(OCH₂Bu^t)₆(py)₂](py = pyridine) yield µ-alkylidene oxo ditungsten compounds, similar reactions with the α,β-unsaturated organic carbonyls CH₂CHCHO, MeCHCHCHO and CH₂CHC(Me)O give 2:1 adducts of three different structural types; the presence of the neighbouring C–C double bond allows chelate behaviour by ring-closure, thereby providing a kinetic diversion from the otherwise facile CO bond cleavage.