Iodoenolcyclization of 2-(1,3-disubstituted-1-allyl)-1,3-dicarbonyl compounds: diastereoselective synthesis of tetrasubstituted dihydrofurans

The iodio-induced cyclization of 2-alkenyl-1,3-dicarbonyl compounds with the mono- and disubstituted double bond occurred with good diastereoselectivity. A study of stereochemical aspects for different substituents on the allyl side chain was carried out. When the substituents were allyl groups, the trans isomers formed preferentially; in the case of aromatic substituents, the reaction lead instead to cis isomers.