C9 conformation of N-(N alpha-[(tert.-butyloxy)-carbonyl]-L-alanyl)-N,N'-dicyclohexylu rea in solid and solution.
An X-ray diffraction study was carried out on a single crystal of N-(N alpha-[(tert.-butyloxy)-carbonyl]-L-alanyl)-N,N'-dicyclohexylur ea belonging to the tetragonal space group P4(1)2(1)2, having cell dimensions a = b = 10.102(3) A, c = 46.067(7) A, V = 4701.2 A3, Z = 8. The crystal structure was solved by direct methods and refined to an R value of 0.056 for 1602 unique reflections with I greater than 2.5 sigma(I). Crystal structure analysis shows the presence of an intramolecular N-H ... O=C H-bond stabilizing the molecule in a folded form similar to that of a beta turn, forming a nine-membered ring. IR and 1H-NMR studies in CDCl3 solution confirm the stable folded conformation found in the crystalline state, as well as the existence of N-H ... O=C H-bonds in the title compound, as in peptides.
Sudarsanakumar
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C
Department of Physics, Indian Institute of Technology, Madras.
Srinivasan
S
S
Jayakumar
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R
D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry; D014961:X-Ray Diffraction
C077700:N-(N(alpha)-(tert-butyloxycarbonyl)alanyl)-N,N'-dicyclohexylurea; D014508:Urea; D000409:Alanine