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Schiff's bases 3 derived from tryptamine react with Brassard's diene 4 in the presence of EtAlCl2 to give functionalized 1,2,5,6‐tetrahydropyridines which are subsequently transformed to indolo[2,3‐a]quinolizines 8–10 by the Bischler‐Napieralski reaction and reduction of the intermediate iminium salts with NaBH4. magnified image
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Lock et al. (1994) studied this question.
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