| 摘要 |
<p>Useful intermediates for preparing a 1-dethia-1-oxacephalosporin and represented by the following formula: <IMAGE> (wherein R is a monovalent group resulting from the elimination of the carbonyl function of an acyl group derived from a carboxylic or carbonic acid; COB is carboxy or protected carboxy; and X is hydrogen or a nucleophilic group) are prepared from the corresponding penicillin 1-oxides of the following formula: <IMAGE> (wherein R, COB, and X are as defined above) by heating, if required in the presence of a desulfurizing reagent, or by exchanging the X group with another one under the condition of an appropriate nucleophilic substitution.</p> |
