Synthesis of 3-methyl- and 3,4-dimethylfurans using alkoxide, thiolate, and phenoxide-mediated cyclization of 4-oxahepta-1,6-diynes bearing sulfur and selenium functional groups

Abstract

We have reported sodium alkoxide- or aryloxide-mediated cyclization of 4-oxahepta-1,6-diynes bearing the phenylsulfanyl group 1a– d. The reactions with diverse sodium alkoxides and aryloxide produced 4-alkoxymethyl- and 4-aryloxymethylfurans 2aa– 2db in good to high yields. Although reactions with sodium benzenethiolate yielded 3,4-bis(phenylsulfanylmethyl)furans 5a– g, they readily desulfanylated in the presence of tributyltin hydride/AIBN to give the 3-methyl- and 3,4-dimethylfuran derivatives 6a– g. This method’s utility was demonstrated by the synthesis of tetrahydronaphthalenyl furan derivatives bearing alkoxy- and aryloxymethyl substituents.