Stereochemistry and conformational analysis of hemirubin

Michael T. Huggins; David A. Lightner

doi:10.1016/S0040-4020(00)00087-9

Stereochemistry and conformational analysis of hemirubin

Michael T. Huggins, David A. Lightner

University of Nevada, Reno

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

Intramolecularly hydrogen-bonded analogs of the natural bile pigment, bilirubin, are very scarce. Nuclear Overhauser effect NMR studies of the newest analog, a hemirubin (1), confirms intramolecular hydrogen bonding and a ridge-tile-shaped conformation. ¹H NMR studies of 1 at sufficiently low temperatures detect conformational enantiomerization, for which an activation barrier of ΔG(+)~16 kcal/mol at 25°C in CDCl₃ has been estimated. Evidence for the presence of dimeric association at low temperatures or high concentrations of 1 is found by the appearance of new sets of resonances, data from which may be used to calculate: ΔG°₂₉₈ (K) +3.4 kcal/mol, ΔH° -5.6 kcal/mol and ΔS°-30.3 cal/deg/mol. (C) 2000 Elsevier Science Ltd.

Original language	English
Pages (from-to)	1797-1810
Number of pages	14
Journal	Tetrahedron
Volume	56
Issue number	13
DOIs	https://doi.org/10.1016/S0040-4020(00)00087-9
State	Published - Mar 24 2000
Externally published	Yes

Scopus Subject Areas

Biochemistry
Drug Discovery
Organic Chemistry

Keywords

Hydrogen bonding
Pyrroles
Stereoisomerism

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10.1016/S0040-4020(00)00087-9

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title = "Stereochemistry and conformational analysis of hemirubin",

abstract = "Intramolecularly hydrogen-bonded analogs of the natural bile pigment, bilirubin, are very scarce. Nuclear Overhauser effect NMR studies of the newest analog, a hemirubin (1), confirms intramolecular hydrogen bonding and a ridge-tile-shaped conformation. 1H NMR studies of 1 at sufficiently low temperatures detect conformational enantiomerization, for which an activation barrier of ΔG(+)~16 kcal/mol at 25°C in CDCl3 has been estimated. Evidence for the presence of dimeric association at low temperatures or high concentrations of 1 is found by the appearance of new sets of resonances, data from which may be used to calculate: ΔG°298 (K) +3.4 kcal/mol, ΔH° -5.6 kcal/mol and ΔS°-30.3 cal/deg/mol. (C) 2000 Elsevier Science Ltd.",

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T1 - Stereochemistry and conformational analysis of hemirubin

AU - Huggins, Michael T.

AU - Lightner, David A.

PY - 2000/3/24

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N2 - Intramolecularly hydrogen-bonded analogs of the natural bile pigment, bilirubin, are very scarce. Nuclear Overhauser effect NMR studies of the newest analog, a hemirubin (1), confirms intramolecular hydrogen bonding and a ridge-tile-shaped conformation. 1H NMR studies of 1 at sufficiently low temperatures detect conformational enantiomerization, for which an activation barrier of ΔG(+)~16 kcal/mol at 25°C in CDCl3 has been estimated. Evidence for the presence of dimeric association at low temperatures or high concentrations of 1 is found by the appearance of new sets of resonances, data from which may be used to calculate: ΔG°298 (K) +3.4 kcal/mol, ΔH° -5.6 kcal/mol and ΔS°-30.3 cal/deg/mol. (C) 2000 Elsevier Science Ltd.

AB - Intramolecularly hydrogen-bonded analogs of the natural bile pigment, bilirubin, are very scarce. Nuclear Overhauser effect NMR studies of the newest analog, a hemirubin (1), confirms intramolecular hydrogen bonding and a ridge-tile-shaped conformation. 1H NMR studies of 1 at sufficiently low temperatures detect conformational enantiomerization, for which an activation barrier of ΔG(+)~16 kcal/mol at 25°C in CDCl3 has been estimated. Evidence for the presence of dimeric association at low temperatures or high concentrations of 1 is found by the appearance of new sets of resonances, data from which may be used to calculate: ΔG°298 (K) +3.4 kcal/mol, ΔH° -5.6 kcal/mol and ΔS°-30.3 cal/deg/mol. (C) 2000 Elsevier Science Ltd.

KW - Hydrogen bonding

KW - Pyrroles

KW - Stereoisomerism

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Stereochemistry and conformational analysis of hemirubin

Abstract

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Keywords

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