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Conformational study of eight‐membered diazocine turn mimics by two‐dimensional NMR spectroscopy
Author(s) -
Bean John W.,
Briand Jacques,
Burgess Joelle L.,
Callahan James F.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01106-0
Subject(s) - chemistry , coupling constant , torsion (gastropod) , dihedral angle , amide , crystallography , ring (chemistry) , stereochemistry , nuclear magnetic resonance spectroscopy , hydrogen bond , molecule , organic chemistry , physics , medicine , surgery , particle physics
The eight‐membered ring conformations of two diazocine turn mimics, methyl‐[2,5‐dioxo‐3‐( S )‐(3‐ω‐tosyl‐guanidino‐propyl)‐4‐methyl‐octahydro‐1,4‐diazocin‐1‐yl]acetate (I) and methyl‐[2,5‐dioxo‐3‐( S )‐(3‐ω‐tosyl‐guanidino‐propyl)‐octahydro‐1,4‐diazocin‐1‐yl]acetate (II), were determined using torsion angle constraints derived from 3 J(C,H) coupling constants extracted from 13 C‐filtered TOCSY spectra with 13 C in natural abundance. For I, the torsion angle constraints derived from 3 J(C,H) coupling constants were in agreement with torsion angle constraints derived from 3 J(H,H) coupling constants extracted from a P.E.COSY spectrum. Similar 3 J(C,H) coupling constants were found for I and II, and they shared an identical eight‐membered ring conformation characterized by two cis ‐amide bonds and a staggered conformation of the trimethylene group in which the H3 proton is proximal to both the H6 and H8 protons.