Phosphorescence of 8-azasteroids and related compounds.
We have investigated the electron absorption, fluorescence and phosphorescence spectra of 8-azasteroids and model compounds containing enaminodicarbonyl fragment. It has been shown that the investigated compounds have absorption and phosphorescence spectra similar in form and position. The results obtained permit the conclusion that the main deactivation channel of the excited singlet state is the intersystem crossing. It is suggested that the investigated 8-azasteroids of enaminodicarbonyl series under light irradiation undergo phototransformations presumably into derivatives with a gamma-pyridone fragment.
Angularly alkylated 8-aza-D-homogonanes
We have established that cyclic azomethines (1-alkyl-substituted 3,4-dihydroisoquinolines) enter into the annelation reaction with cyclic β-triketones (2-acyl-1,3-cyclohexanediones) with formation of C-9 angularly alkylated 8-aza-D-homogonanes. We have shown that the reaction of asymmetric β-triketones (2-acetyl-5,5-dimethyl-4-methoxycarbonyl-1,3-cyclohexanedione) is accomplished regioselectively, leading to the 17-methoxycarbonylated 8-aza-D-homogonane derivative, existing in solutions in the form of a mixture of stereiosomers with respect to C-17 (due to keto-enol tautomerism) and in crystals in the form of a single stereoisomer. The structure of the 8-azo-D-homogonanes has been proven by UV, IR, and PMR spectra.
Studies on the syntheses of heterocyclic compounds. Part 673. New routes to benzo[a]quinolizines
Heating 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline (1) with crotonic anhydride (2) gave 3,4,6,7-tetrahydro-9,10-dimethoxy-4-methylbenzo[a]quinolizin-2-one (5) along with 2-crotonoyl-1,2,3,4-tetrahydro-6,7-dimethoxy-1-methyleneisoquinoline (3) and N-(2-acetyl-4,5-dimethoxyphenethyl)crotonamide (4). Heating the isoquinoline (1) with glutaconic anhydride (17) in pyridine provided 1,6,7,11b-tetrahydro-9,10-dimethoxy-11b-methylbenzo[a]quinolizin-4-one (19).