SYNTHESIS, STRUCTURE, AND PHYSICOCHEMICAL PROPERTIES OF 3-METHYL AND 3,3-DIMETHYL DERIVATIVES OF 1-(4',4'-DIMETHYL-2',6'-DIOXOCYCLOHEX-1'-YL)-3,4-DIHYDROISOQUINOLINE

3,3-Dimethyl- and 3-methyl-1-(4',4'-dimethyl-2',6'-dioxocyclohex-1'-yl)-3,4-dihydroisoquinolines have been synthesized. Crystal and molecular structures of the 3,3-dimethyl derivative have been determined. In the crystalline state this compound exists as a tautomeric form where a hydrogen atom is located at the N atom of the dihydroisoquinoline fragment of the molecule. The tautomeric equilibrium does not shift noticeably in solutions, as shown by IR, UV, and NMR spectroscopy