NEW MATERIAL: A compound of formula I (X, Z is O or S; R1 is 1-5C alkyl, 1-5C fluoroalkyl with 1-3F, 3-5C cycloalkyl, mono- or dihalovinyl, etc.; one of R2, R3 and R4 is 1-4C alkyl, 2-4C alkenyl, etc., another being H or methyl, and the other being H, or two of R2, R3 and R4 are methyl, chloro, etc., the other being H, or all of R2, R3 and R4 are H; one from R5-R8 is 1-4C alkyl, 2-4C alkenyl, etc., another being H, methyl, etc., and the remaining two being H, or all of R5-R8 are H.

EXAMPLE: 3-Amino-6,9-dimethylpyrido[2,3-b][1,5]benzoxazepin-5(6H)-one.

USE: Prevention and treatment of HIV infection.

PROCESS: A compound of formula II is converted to the corresponding alkali (earth) metal compound of formula III, which is then reacted with a reagent of R1Y (Y stands for a detaching group) under alkylation or acylation conditions.