Synthesis of indeno[2,1-a]pyrrolo[3,4-c]carbazole lactam regioisomers using ethyl cis-beta-cyanoacrylate as a dienophile and lactam precursor

摘要

Reported here is the synthesis and characterization of the indenopyrrolocarbazole, ring system utilizing a Diels-Alder reaction with 2-indenylindole and maleimide. Clemmensen reduction of imide 10 furnished the 5-oxo (16) and 7-oxo (17) lactam regioisomers. A new regiospecific route to 5-oxo 16 was developed using ethyl cis-beta-cyanoacrylate as the dienophile. The regio and stereochemical characterization of the cycloadducts was confirmed by X-ray crystallography. [References: 32]