Nucleophilic Intramolecular Cyclization Reactions of Alkynechalcogenolates

Abstract 2-( ortho -Hydroxyphenyl)-alkynethiolates and -selenolates, obtained through base catalyzed ring cleavage of 4-( ortho -hydroxyphenyl)-1,2,3-thiadiazoles and -1,2,3-selenadiazoles, smoothly transform into 2-benzofuranthiolates and -selenolates. These reactive intermediates can be alkylated in high yield. This reaction sequence could be applied to the synthesis of electron rich thiacrown ethers. The 2-( ortho -aminophenyl)-alkynethiolate analogously forms 2-methylsulfanylindole.