| abstract |
Process for 4-halo azetidinones of the formula <IMAGE> wherein R1 is acylamino or diacylamino, X is chloro, bromo or iodo, and R is a carboxy-protecting group which comprises treating a 4-sulfinoazetidinone of the formula <IMAGE> with positive halogen reagent, eg. N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide, hypohalite. The 4-haloazetidinones are useful intermediate for beta -lactam antibiotics. |