Ritter reaction. Synthesis of 1-substituted 3,3,7,9-tetramethyl-2-azaspiro[4.5]deca-6,9-dien- and -1,6,9-trien-8-ones and 7-methoxy-3,3,6,8-tetramethyl-3,4-dihydroisoquinolines

1-(4-Methoxy-3,5-dimethylphenyl)-2-methylpropan-1-ol reacted with nitriles MeSCN, PhCN, MeCN, EtOC(O)CH₂CN] in the presence of concentrated sulfuric acid to give both 1-R-3,3,7,9-tetramethyl-2-azaspiro4,5]deca-6,9-dien- and -1,6,9-trien-8-ones and 1-R-7-methoxy-3,3,6,8-tetramethyl-3,4-dihydroisoquinolines. The reaction with 3,4-dimethoxyphenylacetonitrile afforded 10,11-dimethoxy-1,3,6,6-tetramethyl-1,5,6,12b-tetrahydrodibenzod,f]indole-2,8-dione. Three-component condensation of 2-methoxy-1,3-dimethylbenzene with isobutyraldehyde and nitriles led to the formation of spirocyclic systems and 3,4-dihydroisoquinoline derivatives in lower yield.