abstract |
Compounds of formula (I): ##STR1## wherein W represents a sulfur atom and X represents a group of formula --N(R 1 )--, or W represents a group of formula --N(R 1 )-- and X represents a sulfur atom; R 1 is hydrogen, alkyl or aralkyl; R 2 and R 3 are each hydrogen, alkyl, aralkyl, aryl or aromatic heterocyclic; R 4 is hydrogen, alkyl or aralkyl; and A is alkylene which is optionally substituted by carboxy; and pharmaceutically acceptable salts and esters thereof, have a valuable vasodilatory activity. |