53631-87-1Relevant academic research and scientific papers
Ring Cleavage of a 3-Azidothiophene: Novel Extrusion of Acetylene
Moody, Christopher J.,Rees, Charles W.,Tsoi, Siu Chung
, p. 915 - 920 (2007/10/02)
Mild thermal decomposition of ethyl 2-azido-3-(3-azido-2-thienyl)propenoate (8) results in the cleavage of the thiophene ring with extrusion of acetylene and formation of ethyl 5-cyanoisothiazole-3-carboxylate (10), together with ethyl thienopyridazine-3-carboxylate (9).The former reaction represents the first fragmentation of a five-membered heteroaromatic β-nitrene to extrude an acetylene, and the latter reaction is a rare example of formal intramolecular coupling of nitrenes in solution themolysis.This vinyl azide group is necessary for this cleavage of the thiophene ring and a mechanism is proposed in which the derived nitrene co-ordinates with the thiophene sulphur atom to facilitate ring fragmentation.The analogous furan does not fragment similarly.Diels-Alder cycloadditions of 4-phenyl-1,2,4-triazole-3,5-dione to 2-vinylthiophenes were investigated as an independent approach to the thienopyridazine system, but the fused 4-phenyl-1,2,4-triazoline-3,5-dione ring proved resistant to hydrolytic cleavage.
