NMR study of the conformation of N-(3-pyridinyl)-2- pyridinecarboxamide, N-(3-pyridinyl)acetamide and 2-pyridinecarboxamide
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- Elsevier
Abstract
The IH NMR spectra of N-(3-pyridinyl)-2-pyridinecarboxamide (1), N-(3-pyridinyl)acetamide (2) and 2-pyridinecarbox- amide (3) in CDCI3β, (CD3β)2βCO and CD3βCN have been measured and analyzed by utilising the correlations in the COSY and HETCOR spectra, chemical shifts and coupling constants. 1H NMR spectra in dilute solutions (βΌ1mgmlβ1) and NOE experiments suggest (1) to occur in a single conformation with the 2-pyridyl ring coplanar with the amide plane and the 2-pyridyl nitrogen hydrogen bonded intramolecularly to the N-H. In concentrated solutions of CDCl3β and (CD3β)2βCO, (1) dimerises by cooperative hydrogen bonding. The structure of the dimer was inferred to be similar to that of the adenine- adenine (A-A) base-pair