A two-step synthesis of the N-acylated alpha -azido-omega -aminovalerate. a
common intermediate for the synthesis of midpacamide and dispacamide, is d
escribed. This intermediate undergoes cyclization through the corresponding
alpha -ureido ester derivative to give the 3-methylhydantoin ring present
in midpacamide, whereas the reaction with triphenylphosphine. tosyl isocyan
ate and ammonia followed by cyclization of the resulting guanidine derivati
ve provides the 2-aminoimidazole ring present in dispacamide. (C) 2001 Else
vier Science Ltd. All rights reserved.