Synthesis of ipomeamarone via the [2+3] dihydrofuran annulation

The synthesis of several dihydrofurans of type 179 was accomplished by the flash vacuum pyrolysis of vinyloxiranes of type 178 obtained from the addition of the dienolate of ethyl-2-bromocrotonate (177) to various aldehydes (176). Thus, dihydrofurans were prepared from aldehydes in an overall intermolecular [2+3] dihydrofuran annulation.