| 摘要 |
Process for 1-[ alpha -(carboxy)-4-hydroxy or protected-hydroxybenzyl]-3-acylamidoazetidin-2-one esters, useful intermediates for preparing antibiotic FR 1923, comprising the ring opening of a 2-acyl-3,3-dialkyl-7-oxo- alpha -[4-(protected-hydroxyphenyl]-4-thia-2,6-diazabicyclo[3.2.0]heptane-6- acetic acid, ester sulfoxide with a sulfonic acid and heat to provide a 3-acylamido-4-(2-oxaalkylthio)azetidin-2-one ester which on treatment with sulfuryl chloride affords a reaction product mixture that is then reduced with an organo tin hydride, e.g., tri(n-butyl)tin hydride, to the product. N-Deacylation of the 3-acylamido group followed by acylation with the 3-acyl portion of FR 1923, deblocking of the amino-protecting group and deesterification affords FR 1923.
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