Synthesis of highly functionalized furanones via aldol reaction of 3-silyloxyfurans

The stereoselective aldol reaction of 3-silyloxyfurans with aldehydes in the presence of a Lewis acid is described. N-Bromosuccinimide (NBS)-mediated cyclization of the aldol product leads to the formation of the 2,7-dioxa-bicyclo[2.2.1]heptan-3-one ring system, which represents the formal product of hetero Diels-Alder reaction of the furan with the aldehyde.