摘要 |
The invention relates to compounds of formula (X), and salts thereof, and their use as intermediates in improved manufacturing processes for the synthesis of pharmaceutical compound (I): X is ═O, ═N—OH or ═N—OC(O)Me; Y is hydrogen, PhS- or p-chlorophenylsulfanyl; Z is hydrogen or —CH2COOR1 wherein R1 is selected from hydrogen, optionally substituted hydrocarbyl and optionally substituted heterocyclyl. |