The syntheses are described for centrally expanded bilirubin analogs: >b-homorubins with propionic and butyric acid groups in the positions corresponding to the propionic acids of bilirubin. Their syntheses were accomplished by coupling two equivalents of a reactive monopyrrole (5-(bromomethylene)pyrrolin-2-one) to a dipyrrylethane. The corresponding >b-homoverdins and dehydro->b-homoverdins were prepared by dehydrogenating the rubins or their dimethyl esters using DDQ. As supported by NMR measurements and molecular mechanics calculations, the homorubins are found to engage in conformation-determining intramolecular hydrogen bonding between the dipyrrinone and carboxylic acid moieties. Likewise, the homoverdins are believed to favor intramolecularly hydrogen-bonded conformations.
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机译：描述了针对中心扩展的胆红素类似物的合成：> b -homorubins，在相应于胆红素丙酸的位置具有丙酸和丁酸基团。它们的合成是通过将两当量的反应性单吡咯（5-（溴亚甲基）吡咯啉-2-一）与二吡咯乙烷偶联来完成的。相应的> b -homoverdins和脱氢-> b -homoverdins是通过使用DDQ对红蛋白或其二甲基酯进行脱氢制备的。在NMR测量和分子力学计算的支持下，发现高红红素参与构象确定二吡啶酮与羧酸部分之间的分子内氢键。同样地，认为高等蛋白有利于分子内氢键构型。
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