NaBH4-mediated complete reduction of the α,β-unsaturated ketone units of chalcones in the synthesis of flavans

Abstract

In this chapter, the NaBH4-mediated reduction of both the carbon-carbon double bond and the carbonyl group of chalcones and subsequent acid mediated cyclisation of the resulting saturated alcohols to flavans is described. The chalcones were readily prepared from commercially available acetophenone and salicylaldehyde derivatives. Through this sequence of reactions, 3’,4’-dimethoxyflavan and 3’,4’,8-trimethoxyflavan were prepared in good overall yields.