Hydrogen Bonding: HOC=O· · ·H-N vs. HOC=O· · ·H-C

Monatshefte für chemie
Sanjeev K DeyD A Lightner

Abstract

A chloroform-soluble dipyrrinone, 8,9-bis-(5-carboxypentyl)-2,3-bis-(2-methoxyethoxy)-10H-dipyrrin-1-one, with solubilizing 2-methoxyethoxy β-substituents on the lactam ring and two hexanoic acid groups (one at C(9), the other at C(8) of the pyrrole ring) was synthesized for its ability to form intramolecular hydrogen bonds to the lactam unit from either carboxylic acid, whether in the syn-(Z) or anti-(Z) conformation. In the syn-(Z) conformation, such intramolecular hydrogen bonds can also include the pyrrole N-H. In the anti-(Z), intramolecular hydrogen bonds can include the pyrrole C(7)-H. Evidence for both monomer conformations in equilibrium is provided by (1)H NMR analyses, which indicate that the syn-(Z) is favored over the anti-(Z) and predict an interconversion barrier of approximately 40 kJ mol(-1).

References

Jun 23, 1978·Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character·R BonnettG M Sheldrick
Sep 16, 2000·The Journal of Organic Chemistry·M T Huggins, D A Lightner
Dec 12, 2001·The Journal of Organic Chemistry·M T Huggins, D A Lightner
Jan 6, 2010·Tetrahedron·Suchitra Datta, David A Lightner

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