ACTIVATED MICHAEL ACCEPTORS AS PRECURSORS TO HETEROCYCLES - 1 - 2-AZETIDINONES FROM 2-(ARYLSULFONYL)PROPENOYL CHLORIDES AND AMINES

The addition of NH3 and other primary amines to Z-3-phenyl-2-(arylsulf onyl)propenoyl chlorides gives trans-2-arylsulfonyl-3-phenyl-2-azetidi nones as the major product in addition to the corresponding 2-arylsulf onyl-3-phenylpropenamide. Electron-withdrawing substituents in the ary lsulfonyl group increased the percentage of products derived from 1,4- addition relative to 1,2-addition, while electron-donating substituent s increased the amount of 1,2-addition observed in the product mixture . Addition of alpha-methylbenzylamine gave a 68:32 mixture of the two diastereomers of the trans-azetidinone. The major diastereomer was ide ntified as the 1-(1R)-(3S,4S) and 1-(1S)-(3R,4R) enantiomers 16a by si ngle-crystal X-ray crystallographic analysis, Phenylthio and phenylsul foxo substituents did not promote 1,4-addition, although the addition of ammonia to Z-3-phenyl-2-(phenylsulfoxo)propenoyl chloride (7a) gave a 95:5 ratio of the corresponding propenamide 8a and a 3-(phenylsulfo xo)azetidinone 9a. trans-4-Phenyl-3-(arylsulfonyl)-2-azetidinones 12a and 12c were sulfonated by the pyridine-SO3 complex to give the corres ponding N-sulfonates 28 in > 80% yield. The p-methoxybenzyl substituen t of 15 was removed by eerie ammonium nitrate in CH3CN to give 12a in 70% yield.