Abstract 2, 3-Benzannelated dipyrrinone analogs (1 and 2) of xanthobilirubic acid (3) are prepared by base-catalyzed condensation of isoindolinone (5) and indolin-2-one (6) respectively, with methyl 3-(2-formyl-3, 5-dimethyl-1H-pyrrol-4-yl) propanoate (4). Nuclear Overhauser effect H-nmr studies indicate that both 1 and 2 adopt preferentially a syn-Z configuration. The former forms a hydrogen-bonded homodimer in nonpolar solvents; the ...
[Al-Hazimi, Hassan M. G.; Jackson, Anthony H.; Knight, David W.; Lash, Timothy D. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1987 , p. 265 - 276]
