New Cyclization of 4-Oxahepta-1,6-diynes Bearing Sulfur and Selenium Functional Groups

New cyclizations of 1-sulfanyl- and -selany1-4-oxa-1,6-heptadiynes using sodium alkoxide or thiolates provided 4-alkoxymethy1-3-phenylsulfanyl- and 3,4-bis(sulfanylmethyl)furans in high yields.