A CONVENIENT APPROACH TO FURAN-DERIVATIVES BY I-2-INDUCED CYCLIZATION OF 2-ALKENYL SUBSTITUTED 1,3-DICARBONYL COMPOUNDS

5-iodoalkyl-4,5-dihydrofurans 2, 5-alkylidine-4,5-dihydrofurans 3 and 2,3,5-trisubstituted furans 4 are obtained through a simple sequence, involving, in the key-step, a regio- and stereoselective iodoenoletherification of 2-alkenyl substituted 1,3-dicarbonyl compounds 1.