1379826-28-4Relevant articles and documents
Efficient synthesis of maxonine analogues from N-substituted benzyl-1-formyl-9H-β-carbolines
Hutait, Samiran,Biswas, Subhasish,Batra, Sanjay
supporting information; scheme or table, p. 2453 - 2462 (2012/05/20)
Acid-catalyzed Pomeranz-Fritsch-type reaction between the acetal group at C-1 and the arene unit of the benzyl group at N-9 in 9-substituted benzyl-1-(dimethoxymethyl)-9H-β-carboline affords fused-β-carbolines that can be readily oxidized to furnish a maxonine-type framework. Mechanistically, the reaction proceeds via a protonated aldehyde as the intermediate, which undergoes attack by the activated arene subunit of the benzyl moiety. On the other hand, the Morita-Baylis-Hillman adducts of 1-formyl-N-substituted benzyl-9H-β-carbolines undergo an efficient P 2O5-mediated intramolecular Friedel-Crafts reaction between the secondary hydroxy group and the activated phenyl group of the benzyl subunit to yield fused-β-carbolines. Investigations into the scope of the substrates reveal that the success of the methodology relies on the degree of activation of the phenyl ring. For substrates having less-activated phenyl groups, indolizinoindole derivatives were isolated in moderate yields only. A simple and efficient synthesis of maxonine analogues from N-substituted benzyl 1-formyl-9H-β-carbolines through sequential Pomeranz-Fritsch reaction and oxidation is demonstrated. In an extension of the study, synthesis of new fused β-carbolines has been accomplished by P2O5-mediated Friedel-Crafts reaction of the Morita-Baylis-Hillman adducts of these aldehydes.
