The invention provides a process for preparing a compound of the formula: ##STR1## or a base salt thereof, wherein R.sup.2 is hydrogen or C.sub.1 -C.sub.6 alkyl optionally substituted by up to 3 substituents each independently selected from the group consisting of C.sub.1 -C.sub.6 alkoxy and C.sub.1 -C.sub.6 alkoxy(C.sub.1 -C.sub.6 alkoxy)-; and R.sup.3 is C.sub.1 -C.sub.6 alkyl or benzyl, said benzyl group being optionally ring-substituted by up to 2 nitro or C.sub.1 -C.sub.4 alkoxy substituents comprising reacting a compound of the formula: ##STR2## wherein R.sup.1 is C.sub.1 -C.sub.4 alkyl, phenyl or benzyl or C.sub.1 -C.sub.4 alkoxy; and R.sup.2 and R.sup.3 are as previously defined for a compound of the formula (I), with hydrogen peroxide or a source of peroxide ions: said process being optionally followed by conversion of the compound of the formula (I) to a base salt thereof. The present invention also relates to novel compounds of the formula (II).
本发明提供了一种制备式为:##STR1##或其碱盐的化合物的过程,其中R.sup.2是氢或C.sub.1-C.sub.6烷基,可选地被选自C.sub.1-C.sub.6烷氧基和C.sub.1-C.sub.6烷氧基(C.sub.1-C.sub.6烷氧基)的3个取代基中的每个独立选择的取代基取代;R.sup.3是C.sub.1-C.sub.6烷基或苄基,所述的苄基可选地被选自最多2个硝基或C.sub.1-C.sub.4烷氧基取代,包括将式为:##STR2##其中R.sup.1是C.sub.1-C.sub.4烷基,苯基或苄基或C.sub.1-C.sub.4烷氧基; R.sup.2和R.sup.3如前所述对于式(I)的化合物,与
过氧化氢或过氧化物离子的来源反应:该过程随后可选择将式(I)的化合物转化为其碱盐。本发明还涉及式(I)的新化合物。