The Staudinger reaction is one of the most important methods in synthesis of β-lactams. 3-(Thiophen-2-yl)-β-lactam is one class of important β-lactam derivatives. A convenient and new method was developed to synthesize 2-diazo-1-(thiophen-2-yl)-ethanone from 4,4,4-trifluoro-1-(thiophen-2-yl)- 1,3-butanedione and tosyl azide. A series of 3-(thiophen-2-yl)-β-lactams were synthesized via the Staudinger reaction of imines and thiophen-2-ylketene generated thermally from 2-diazo-1-(thiophen-2-yl)-ethanone. The stereoselectivity of the Staudinger reaction was also investigated. The results indicate that thiophen-2-ylketene is a more electron-rich Moore ketene than phenylketene and its electronic property locates between those of 4-methoxyphenylketene and 4-methylphenylketene.

Key words: β-lactam, Staudinger reaction, stereoselectivity, diazoketone, ketene