METHOD FOR PREPARING SILDENAFIL.

摘要

The present invention refers to a process for preparing a compound having a formula (I), also known as sildenafil by the cyclization of a compound with structural formula (II) in the presence of a base. The invention also comprises the preparation of a compound having a formula (II) by chlorosulfonation and a subsequent reaction with N-methyl piperazine. (see formulas).