STRUCTURAL ASPECTS OF IODINE-PROMOTED ONE-POT CYCLIZATION OF O-BIS(METHYLTHIO)STILBENES TO THIENO[3,2-b]THIOPHENE DERIVATIVES: SYNTHETIC TRIALS OF TETRATHIENOACENES FROM 1,2-BIS(3-METHYLTHIOTHIOPHEN-2-YL)ETHENES

摘要

In this paper, attempted reactions for the synthesis of tetrathienoacenes from 1,2-bis(3-methylthiothiophen-2-yl)ethenes by the iodine-promoted one-pot cyclization reaction were described. X-Ray structural analyses of the precursors indicated that the failure of reactions is closely related to the molecular structures around the reaction moiety, in particular, the bond angles defined by the aromatic ring and the neighboring carbon atom in the ethene moiety. We speculate that the larger angles in the 1,2-bis(3-methylthiothiophen-2-yl)ethenes make the intramolecular nucleophilic attack of the methylthio groups to the iodonium intermediate difficult.