The invention is concerned with novel dioxolane derivatives of the formula:-
in which Ra is hydrogen or (1-4C)alkyl and Rb is (1-4C)alkyl or phenyl optionally bearing a halogeno substituent; their production; and their use for the manufacture of certain known anti-arthritic acids of the formula:-
and, in particular, those acids in which Ra=Rb=methyl or Ra=ethyl and Rb =phenyl, by a novel reduction process. The preferred reduction procedures involve the use of an alkali metal borohydride or cyanoborohydride in the presence of a noble metal catalyst, or the use of an α-branched alkyl or cycloalkyl Grignard agent.
The use of the derivatives of formula avoids the need for potentially toxic reagents and reactive intermediates in the previously known processes for the production of the acids of formula V.
本发明涉及式如下的新型二
氧戊环衍
生物
其中Ra为氢或(1-4C)烷基,Rb为(1-4C)烷基或任选带有卤代基的苯基;它们的生产;以及它们用于制造某些已知的式为:-的抗关节炎酸。
特别是Ra=Rb=甲基或Ra=乙基和Rb=苯基的那些酸,采用新的还原工艺。优选的还原过程包括在
贵金属催化剂存在下使用碱
金属
硼氢化物或
氰基硼氢化物,或使用 α-支链烷基或环烷基格氏剂。
使用式的衍
生物可以避免在以前已知的生产式 V 酸的工艺中使用可能有毒的试剂和反应中间体。