1-Functionalized 5,6-Dimethyl-6H-pyrido[4,3-b]carbazoles (Ellipticines) and Analogues: A New Rapid Synthesis

Abstract
4-Acetyl-2-chloro-3-lithiopyridine ethylene glycol ketal reacts with 3-formyl-5-methoxy-1-methylindole and 3-formyl-1-methyl-1H-pyrrolo [3,2-c] pyridine, giving the expected alcohols whose triethylsilane-trifluoroacetic acid reduction at room temperature followed by ketal hydrolysis and cyclisation in acidic medium leads in one step to 1-chloro-9-methoxy-5,6-dimethyl-6H-pyrido [4,3-b] carbazole and 10-chloro-5,6-dimethyl-5H-pyrido [3'',4'':4,5]pyrrolo [2,3-g] isoquinoline respectively, in 30% overall yields. 1-Functionalized 11-nor-ellipticines and analogues are thus obtained via a two-sep convergent pathway which appears to be particularly attractive for the rapid synthesis of various condensed heterocylic systems.
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