N-Heterocyclic carbene catalysed redox isomerisation of esters to functionalised benzaldehydes† †Electronic supplementary information (ESI) available: Experimental procedures and 1H and 13C NMR of new materials. See DOI: 10.1039/c4sc03726j Click here for additional data file.

N-Heterocyclic carbene catalysed redox isomerisation with reduction about the carbonyl has been developed in the transformation of trienyl esters to tetrasubstituted benzaldehydes. The reaction proceeds in good to excellent yield, and in cases that provide 2,20-biaryls, enantioselectivity is observed. Mechanistic studies demonstrate the intermediacy of a cyclohexenyl b-lactone, while implicating formation of the homoenolate as turnover limiting.