| abstract |
Compounds of formula (I): n n in which: W represents a sulphur or oxygen atom and X represents a group of formula -N(R¹)-, or W represents a group of formula -N(R¹)- and X represents a sulphur or oxygen atom; R¹ is hydrogen, alkyl or aralkyl; R² and R³ are each hydrogen, alkyl, aralkyl, aryl or aromatic heterocyclic; R⁴ 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. |