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Rotational Barriers and 15 N Chemical Shifts of N ‐Acyl‐ N ‐alkyl‐substituted Amino Acids
Author(s) -
Ozawa Tomonaga,
Isoda Yuichi,
Watanabe Hiroshi,
Yuzuri Tomoaki,
Suezawa Hiroko,
Sakakibara Kazuhisa,
Hirota Minoru
Publication year - 1997
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199705)35:5<323::aid-omr98>3.0.co;2-5
Subject(s) - chemistry , steric effects , chemical shift , nitrogen atom , alkyl , nitrogen , medicinal chemistry , stereochemistry , amino acid , organic chemistry , biochemistry
Rotational barriers about the C—N bonds of several N ‐acyl‐ N ‐methyl‐α‐amino acids and their esters R 3 CO—N(R 4 )—CR 1 R 2 —COOR 5 , and also N ‐Boc‐protected dipeptides, were determined and the steric effects caused by the substituents R 1 –R 5 are discussed by comparing them with the results of MM3 calculations on these amides. Bulky substituents on both the acyl group and the nitrogen atom were shown to have lower Δ G ‡ . In the series of N ‐acylglycines with variable R 3 , the 15 N chemical shifts were correlated with Δ G ‡ . © 1997 by John Wiley & Sons, Ltd.