Substituent Effects on Pyrid-2-yl Ureas toward Intramolecular Hydrogen Bonding and Cytosine Complexation
Resource
The Journal of Organic Chemistry 69 (6): 1866-1871
Journal
The Journal of Organic Chemistry
Journal Volume
69
Journal Issue
6
Pages
1866-1871
Date Issued
2004
Date
2004
Author(s)
Abstract
Equilibria between two conformational isomers of pyrid-2-yl ureas, the (E,Z) and (Z,Z) forms, have been studied in DMF-d(7) at -70 degrees C. Most of them show a small preference for the (E,Z) form with an equilibrium constant K(i) around 1-2. However, the K(i) value for 1-methyl-2-(3-(pyrid-2-yl)ureido)pyridinium iodide (12) was found to be 14.2 +/- 1.2. That is 1 order of magnitude larger than those of the others, which indicates that the positively charged 1-methylpyridinium-2-yl substituent would facilitate the (E,Z) form formation. Pyrid-2-yl ureas bind cytosine in DMF-d(7) with binding constants K(B) ranging from 30 to 1700 M(-1). Electron withdrawing substituents, such as the 4-O(2)NC(6)H(4)- or 1-methylpyridinium-4-yl substituent, preferentially facilitate the intermolecular cytosine complexation with large binding constants.
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Type
journal article
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