Direct generation of lithium homoenolates from 3-aryl α,β-unsaturated ketones or esters by an arene-catalysed lithiation: Synthesis of substituted tetrahydrofurans and γ-butyrolactones

Abstract

The reaction of α,β-unsaturated ketones 1 with an excess of lithium powder, a catalytic amount of naphthalene (4 %) and different carbonyl compounds in the presence of boron trifluoride in THF at −78 – 0°C yields, after treatament with silyl nucleophile and final hydrolysis, the expected substituted tetrahydrofurans 5. Similar methodology applied to β-aryl acrylic esters 6, but without using boron trifluoride or silyl reagents yields the corresponding lactones 7.