Contrary to a report that the reaction of benzo[b]cyclohepta[e][1,4]oxazine 1 with α,γ-diamine 2b produces 1,2,3,4-tetrahydrocyclohepta[b][1,4]diazepine 4, the product was found to be 2-phenyl-3,4,5,6-tetrahydropyrimidine 5b and is peculiar to the reaction of 1 with α,γ-diamines 2 as well as β-aminamide 7.