Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

Abstract

The first total synthesis of the pyrrolo[2,3-c]quinoline alkaloid trigonoine B (1) was accomplished via a six-step sequence involving the construction of an N-substituted 4-aminopyrrolo[2,3-c]quinoline framework via electrocyclization of 2-(pyrrol-3-yl)benzene containing a carbodiimide moiety as a 2-azahexatriene system. The employed six-step sequence afforded trigonoine B (1) in 9.2% overall yield. The described route could be employed for the preparation of various N-substituted 4-aminopyrroloquinolines with various biological activities.

Recent Advances in the Synthesis and Biological Activity of Pyrrolo[2,3-c]pyridines

“…The treatment of these compounds with CBr 4 , PPh 3 , and TEA led to the formation of carbodiimides 148. The subsequent deprotection of carbodiimides 148 with tetrabutylammonium fluoride (TBAF) was accompanied by the electrocyclization reaction and the in situ formation of the desired marinoquinolines 149 (Scheme 42) [70].…”

Novel Approach to the Construction of Fused Indolizine Scaffolds: Synthesis of Rosettacin and the Aromathecin Family of Compounds

“…Our research group has been interested in the unique structure and pharmacological action of condensed heteroaromatic compounds and we have been searching for highly active compounds based on these naturally occurring compounds and their derivatives. To date, we have achieved the total synthesis of several such compounds using various types of 6π-electron system (hexatriene, 1- and 2-azahexatriene) electrocyclic reactions, such as asiaticumine [ 27 ], marinoquinolines [ 28 ], trigonoine B [ 29 ], girinimbine [ 30 ], and karnatakafuran B [ 31 ]. We have also published the total synthesis of ( R )-(–)-pyridindolols using another synthetic approach that involved thermal cyclization of 3-alkynylindole-2-aldoxime to construct the key β-carboline N -oxide intermediate [ 32 , 33 ].…”