Synthesis of 1'-substituted 2-amino-spiro(4H-3,1-benzoxazine-4,4'-piperidine) derivatives.

In the cyclization reaction of 4-hydroxy-4-[2-(N/-substituted carbamoyl) aminophenyl] piperidine derivatives (3) by treatment with acid, 2-amino-spiro [4H/-3, 1-benzoxazine-4, 4′-piperidine] derivatives (4) were obtained.One of the products, 2-methylamino-spiro [4H/-3, 1-benzoxazine-4, 4′-piperidine] (4g), was converted to 1-(2-hydroxy-2-phenethyl)-2-methylamino-spiro [4H/-3, 1-benzoxazine-4, 4′-piperidine] derivatives (12), which are our target compounds for pharmacological screening tests on antihypertensive activity. However, these compounds did not show any remarkable antihypertensive activity.