Abstract
A series of 3, 8-disubstituted-1-oxa-3, 8-diazaspiro [4, 5] decan-2, 4-diones (XI) were synthesized for pharmacological testing. 3-Substituted-8-benzyl compounds (IIIb-h), the intermediates of XI, were prepared by the following three methods : 1) condensation of methyl 1-benzyl-4-hydroxyisonipecotate (II) with urea, followed by alkylation, 2) treatment of II with isocyanates and 3) reaction of 1-benzyl-4-cyano-4-piperidinol (I) with isocyanates followed by hydrolysis. The last method was inferior to the other two methods. Reductive debenzylation of III followed by condensation with appropriate halides afforded XI. Among the compounds (XI) synthesized, 8-[3-(2-chlorophenothiazin-10-yl) propyl]-3-methyl compound (XIa) had excellent central nervous system depressing activities.
