SYNTHESIS AND UNUSUAL PROPERTIES OF AN 8,12-BIS-PIVALIC ACID ANALOG OF BILIRUBIN

被引：6

作者：

BOIADJIEV, SE ^{[1
]}

HOLMES, DL ^{[1
]}

ANSTINE, DT ^{[1
]}

LIGHTNER, DA ^{[1
]}

机构：

[1] UNIV NEVADA,DEPT CHEM,RENO,NV 89557

来源：

TETRAHEDRON | 1995年 / 51卷 / 39期

基金：

美国国家卫生研究院;

关键词：

D O I：

10.1016/0040-4020(95)00658-U

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

A sterically congested analog of bilirubin with propionic acid groups replaced by pivalic acids (1) was synthesized from methyl 3-(2,4-dimethyl-5-ethoxycarbonyl-1H-pyrrol-3-yl)-2-methylpropionate (8). UV-visible and NMR spectroscopic analyses of 1 suggest intramolecularhydrogen-bonding and a preference for a ridge-tile conformation. The activation parameters for M reversible arrow P conformational inversion of 1 were determined by dynamic NMR analysis to be Delta H double dagger 19.7 +/- 1.4 kcal/mole and Delta S double dagger +/- 10.4 +/- 4.5 eu. Molecular dynamics computations predict a global energy minimum for a somewhat more open ridge-tile conformation as compared with bilirubin. Circular dichroism of the pigment complex with human serum albumin gives a bisignate Cotton effect: Delta epsilon(431)(max) = -51, Delta epsilon(382)(max) = +30, with the opposite signed order as compared with that found for the parent mesobilirubin-XIII alpha and bilirubin.

引用

页码：10663 / 10678

页数：16