Organocatalytic [3+2] annulation of β-tetralones with α, β-unsaturated aldehydes

Abstract

The NBS-mediated organocatalytic cascade synthesis of 4,5-dihydronaphtho[2,1-b]furan-1-carbaldehydes from α, β -unsaturated aldehydes and 2-tetralones have been developed. In this synthesis strategy, the C1 of in-situ-generated brominated 2-tetralone as an identical twin electron donor-acceptors, and the Cβ and Cα of enals as the heterogenous twin electron acceptor-donors. The process has been realized by a synergistic amine/ p-TSA catalyzed one-pot cascade Michael addition-cyclopropanation-ring opening-Oxa Michael addition in mild condition and without the use of transition metals.