Chemical Modification of Plant Alkaloids. 4. Reaction of Cotarnine with Bifunctional NH- and CH-Acids

1-Substituted 1,2,3,4-tetrahydroisoquinoline systems were prepared by reaction of cotarnine with the NH-and CH-acids methyl- and acyl derivatives of pyrazole and 1,3-dicarbonyl reagents. Depending on the structure and reaction conditions, bifunctional pyrazole nucleophiles can give substitution products at the N atom, methyl, or acyl group; 1,3-diketones, at the terminal methyl. Rearrangements occurring during the reaction of cotarnine with bifunctional substrates were studied.