Synthesis and structure elucidation of pyrimidobenzimidazoles and fused derivatives II.: Dodecahydrobenzimidazo-[2,1-b]quinazolines and decahydrobenzimidazo-[2,1-b]benzo[h]quinazolines

The cyclization reactions of trans-3a-hexahydro-2-benzimidazolamine with 2-alkylidene- and 2-benzylidenecyclohexanones and alpha-tetralones, respectively, yield mixtures of two isomeric condensates each. Thorough high resolution NMR analyses (H-1 and C-13 NMR, HH-COSY, gs-HSQC, gs-HMBC, 1D TOCSY, and ID NOE difference spectra) revealed that the corresponding isomers are in all cases linearly fused diastereomeric 12 alpha- and 12 beta-substituted trans-6a alpha-dodecahydrobenzimidazo[2,1-b]quinazolines and 7 alpha-substituted trans-8a beta- and trans-8a alpha-decahydrobenzimidazo[2,1-b]benzo[h]quinazolines, respectively. The formation of corresponding angularly fused regioisomers was not observed so far. The stereochemistry and the tautomerism of some bares and their hydrochlorides as well as the regiospecific course of the cyclization reactions are discussed. Biological tests showed that the novel compounds don't exert remarkable antibacterial and antimycotic effects.