| 摘要 |
The invention provides a novel process for opening the ring of 2-R-6-(1'-R1-oxycarbonyl-2'-methyl-prop-1'-enyl)-1-oxa-3,6-diaza-4S,5R -bicyclo[3,2,0]hept-2-en-7-one by treatment with a sulfonic acid salt thereby forming R1 2-(2'R-R-oxy-3'S-amino-4'-oxo)azetidinyl-3-methyl-2-butenoate sulfonic acid salts which can provide oxapenicillins by two different routes depending on the substituent desired on the carboxamido group of the 1-oxapenicillins. In the alternate processes, new intermediates are also provided.
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