The synthesis of AWD 131-138 is obtained as illustrated in Scheme 25002101a: The alkylation of 4-chloroaniline (I) with chloroacetic acid methyl ester in ethanol gives N-(4-chlorophenyl)glycine methyl ester (II), which is added to cyanate by means of hydrochloric acid in glacial acetic acid to yield 3-(4-chlorophenyl)hydantoic acid methyl ester (III). The cyclization in hydrochloric acid yields 1-(4-chlorophenyl)hydantoin (IV), which is finally condensed with morpholine.