Wenderoth, Lind & Ponack
Production of 1-oxacephams and intermediates
 Useful intermediates, 7.alpha.-acylamino-3-(oxo or exomethylene)-1-dethia-1-oxacepham-4.alpha.-carboxylates, are produced by the intramolecular carbenoid insertion of a 2-diazo-3-(oxo or exomethylene)-4-(3.alpha.-acylamino-2-oxoazetidin-4.beta.-yl)oxybutyrate prepared in several steps from the corresponding oxazolinoazetidinone and diketone. 
Shionogi & Co., Ltd.
Y C C C C C C C C C
Y02P C07C C07C C07F C07D C07F C07D C07F C07C C07D
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Hikaru Hiromi Sadao Wataru Teruji
Itani Takahashi Yamamoto Nagata Tsuji