Process for the preparation of a compound of formula or a salt thereof ##STR1## wherein R.sub.1 represents a hydrogen atom or a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)-- wherein R.sub.2 represents a phenyl, tolyl or C.sub.1-4 alkyl group and R.sub.3 represents a hydrogen atom or a phenyl or C.sub.1-4 alkyl group, which process comprises contacting nickel in an oxidation state of at least 3 with a 3-hydroxymethyl azetidine derivative of formula ##STR2## wherein R.sub.4 represents a group of formula R.sub.2 SO.sub.2 or phenyl--CH(R.sub.3)-- and R.sub.5 represents a hydrogen atom or a hydroxymethyl group or a group of formula COOH or a salt thereof, followed, where R.sub.5 is not a hydrogen atom, by the decarboxylation of the compound of the 3,3-dicarboxylic intermediate product or a salt thereof and, if desired to produce a compound in which R.sub.1 represents a hydrogen atom, by deprotection of the N-atom. Also, novel N-substituted azetidine carboxylate derivatives of the formula ##STR3## wherein X represents a group CH.sub.2 OH or COOY where Y represents a hydrogen or an alkali or alkaline earth metal atom.
制备式或其盐的化合物的过程,其中R1代表氢原子或式R2SO2或苯基-CH(R3)-的基团,其中R2代表苯基,
甲苯基或C1-4烷基基团,R3代表氢原子或苯基或C1-4烷基基团,该过程包括将至少为3的氧化态的
镍与式的3-羟甲基氮杂环衍
生物接触的步骤##STR2##其中R4代表式R2SO2或苯基-CH(R3)-的基团,R5代表氢原子或羟甲基基团或式COOH或其盐的基团,如果R5不是氢原子,则紧随其后的是3,3-二
羧酸中间产物或其盐的化合物的脱羧作用,如果需要制备R1代表氢原子的化合物,则通过去保护N-原子来实现。此外,还提供了新的N-取代的氮杂
环羧酸盐衍
生物的公式##STR3##其中X代表基团CH2OH或COOY,其中Y代表氢或碱
金属或碱土
金属原子。