- Synthesis and properties of mesobilirubins XIIγ and XIIIγ and their mesobiliverdins
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The title pigments, with propionic acid groups displaced to the lactam end rings, were synthesized for the first time by the "1 + 2 + 1" approach, coupling two equivalents of a monopyrrole to a dipyrrylmethane (to give XIIγ), or the "2 + 2" approach, self-coupling two equivalents of a dipyrrinone (to give XIIIγ). Using the "1 + 2 + 1" approach, mesobilirubin IIIα was also prepared. Mesobilirubins XIIγ and XIIIγ are more polar than mesobilirubin IIIα and unlike IIIα cannot effectively engage the propionic acid groups in intramolecular hydrogen bonding to the dipyrrinone components. The new mesobilirubins give exciton coupled circular dichroism spectra in the presence of human serum albumin or quinine, with the XIIγ isomer exhibiting Cotton effect intensities nearly as strong as those from the IIIα isomer; whereas, the XIIIγ isomer exhibits far weaker intensities. Mesobilirubin IIIα requires glucuronidation for hepatobiliary elimination; whereas, XIIγ and XIIIγ do not, and they are excreted intact across the liver into bile. The corresponding biliverdins XIIγ and XIIIγ are reduced only slowly by biliverdin IXα reductase, in contrast to the fast reduction of the natural IXα isomer. Graphical abstract: [Figure not available: see fulltext.]
- Sabido, Portia Mahal G.,Lightner, David A.
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- An efficient method for the conversion of 2-bromo-5-tosylpyrroles to the corresponding 5-tosylpyrrolinones as the D-ring of phycocyanobilin derivatives
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2-Bromo-5-tosylpyrroles were efficiently converted to the corresponding 5-tosylpyrrolinones as the D-ring of phycocyanobilin (PCB) derivatives by treating with DMSO and Zn in TFA in the presence of a catalytic amount of iodine. PCB derivatives modified at the D-ring were prepared in free acid forms employing the resulting 5-tosylpyrrolinones toward structure/function analysis of phytochrome.
- Takeda, Shuzo,Jayasundera, Krishanthi Padmarani,Kakiuchi, Takashi,Kinoshita, Hideki,Inomata, Katsuhiko
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p. 590 - 591
(2007/10/03)
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- An efficient method to construct the A,B-rings component toward total syntheses of phycocyanobilin and its derivative as a photoprobe
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Total syntheses of physocyanobilin and its derivative bearing a photoreactive group at the D-ring accomplished by developing a new and efficient method for the construction of A,B-rings component, which consists of the Wittig-type new coupling reaction of 4-(1-methoxyethyl or 1- tosylethyl)-3-methyl-5-tosyl-1,5-dihydro-2H-pyrrol-2-one and a 2-formyl pyrrole derivative in the presence of (n)Bu3P and a base, followed by reduction with aluminum amalgam and a subsequent acid or base treatment.
- Jayasundera, Krishanthi Padmarani,Kinoshita, Hideki,Inomata, Katsuhiko
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p. 497 - 500
(2007/10/03)
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- An intramolecularly hydrogen bonded dihydrotripyrrinone
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A yellow tripyrrole analog (1) of bilirubin has been synthesized, and its lone propionic acid group is found to engage in conformation determining, intramolecular hydrogen bonding in solution and in the crystal. Molecular modelling and X-ray crystallography reveal an abbreviated ridge-tile or L-shape conformation in which an essentially planar dipyrrinone is hydrogen bonded to the single opposing propionic acid group. In the (arbitrary) (P)-helicity ridge-tile, the torsion angles about C(10) are computed to be 55° and 61° by molecular dynamics and found to be 66° and 53° in the crystal. Such torsion angles lead to an interplanar dihedral angle (~93°) between the dipyrrinone and its adjoining pyrrole that is very close to the dihedral angle (~98°) found in intramolecularly hydrogen bonded bilirubin.
- Tipton, Adrianne K.,Lightner, David A.
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p. 425 - 440
(2007/10/03)
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- Syntheses of 3,4-disubstituted 2-tosylpyrroles and 5-tosyl-1,5-dihydro-2H-pyrrol-2-ones starting from ethyl 3,4-disubstituted 2-pyrrolecarboxylates
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The syntheses of 3,4-disubstituted 2-tosylpyrroles and 5-tosyl-1,5-dihydro-2H-pyrrol-2-ones were accomplished via 3,4-disubstituted 2-iodo-5-tosylpyrroles starting from ethyl 3,4-disubstituted 2-pyrrolecarboxylates.
- Murata, Yasue,Kinoshita, Hideki,Inomata, Katsuhiko
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p. 3339 - 3344
(2007/10/03)
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