Chemistry of phosphorus ylides 21 new route for the synthesis of azetidinones. Reaction of phosphonium ylides with benzil-, o-naphthoquinone-, and triketonemonoanils

Active vinylidenetriphenylphosphoranes are nucleophilic reagents which can be con- sidered as versatile synthons for the synthesis of new heterocycles. The active phosphacumulene ylides, namely N-phenylimino- 2a , 2-oxo- 2b or 2-thioxo-vinylidenetriphenylphosphoranes ( 2c ), react with benzil- ( 1a,b ), o-naphthoquinone- ( 8 ), or triketone-monoanils ( 11 ), to give the corresponding phenylimino- ( 3a, d, 9a, 12a ), oxo- ( 3b, e, 9b, 12b ), or thioxoazetidinones ( 3c, f, 9c, 12c ), respectively, which constitute an important class of organic compounds with medicinal and biological importance. On the other hand, quinone monoanils 1a, 8, 11 can be converted by reaction with the stabilized alkylidenephosphoranes ( 5a–d ), namely acetylmethylene- 5a , methoxycarbonylmethylene- 5b , ethoxycarbonylmethylene- 5c , and benzoylmethylene-triphenylphosphorane 5d , into the phosphoranylidenes ( 7a–d, 10a–d, 13a–d ). No reaction was observed between iminophosphorane ( 14 ) and the monoanil ( 11 ). The structures of the new products were assigned according to consistent analytical and spectroscopic data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:476–483, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20144