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-d iazabicyclo[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.
制备抗生素FR 1923的有用中间体1-[.alpha.-(羧基)-
4-羟基或保护羟基苄基]-3-酰胺基吖唑啉-2-
酮酯的过程包括以下步骤:将2-酰基-3,3-二烷基-7-氧代-.alpha.-[4-(保护羟基苯基)-4-
硫-2,6-二
氮杂双环[3.2.0]
庚烷-6-
乙酸酯亚砜与
磺酸加热,开环得到3-酰胺基-4-(2-氧代
硫代烷基)吖唑啉-2-
酮酯,再经过亚砜
氯化
氯处理得到反应产物混合物,随后用
有机锡氢化物,例如三正
丁基锡氢化物,还原得到产物。对3-酰胺基团进行脱酰基化,然后与FR 1923的3-酰基部分进行酰化,去保护
氨基团和去酯化得到FR 1923。