Synthesis of 1′-substituted and 1′,3′-disubstituted (±)-2R*, 11bS*-9,10-Dimethoxy-1,3,4,6,7,11 b-Hexahydrospiro-[benzo[a]quinolizin-2,5′-imidazolidine]-2′,4′-diones

The results of the reaction between (±)-2R*,11bS*-2-alkyl(aryl)amino-1,3,4,6,7,11b-hexahydrobenzo[a]-quinolizine-2-carbonitriles 2 and isocyanates under a variety of experimental conditions are discussed. The ureides 3 and iminohydantoins 4 thus obtained were used to prepare N₃-monosubstituted and N₁,N₃-disubstituted derivatives of the (±)-2R*,11bS*-9,10-dimethoxy-1,3,4,6,7,11b-hexahydrospiro[benzo[a]quinolizin-2,5′-imidazolidine]-2′,4′-dione system 1 . The stereochemistry of these compounds is discussed, on the basis of spectroscopic evidence and study of their chemical reactivity.