Synthesis Of N-Alkyl-1,2,4-Oxadiazinones As Angiotensin-Ii (At1) Receptor Antagonists

4-Alkyl-1,2,4-oxadiazinones were prepared by regiospecific alkylation of the corresponding 4H-oxadiazinones, which were synthesized by a trimethylaluminum mediated cyclization reaction. Alkylation was regiospecific and generally facile; in one example, however, an unusual fragmentation reaction occurred. A homochiral oxadiazineone was also prepared and alkylated under the described conditions. 4-Biphenylmethyl-1,2,4-oxadi-azinones were potent angiotensin-II receptor antagonists.