The conformational analysis of saturated heterocycles. Part XXXVIII. N-alkylpiperidine and N-alkylmorpholine N-oxides

Computational studies of the structural and transport properties of the cellulose–water–amine oxide system

“…1, was to be found predominantly in the oxygen-axial-methyl-equatorial conformation and not in the oxygen-equatorial-methyl-axial form. 5 Amine oxide is perhaps the most effective solvent known for cellulose and therefore is of great interest in the present study. However, it was unclear, due to the unusual chemical nature, especially of the nitrogen oxygen bond, whether it would be possible to obtain reliable results for this molecule from any of the standard published force-fields: hence the use of ab initio surface energy parameterisation techniques to obtain a reliable description of both the interatomic potentials within this molecule and the partial atomic charges.…”

“…A total of 70 random structures were then generated using the Distort code available from Molecular Simulations. 5 Following single point calculations at the 6-31G*/MP2 level, 6 of the random structures were discarded due to the high energies produced, leaving a total of 64 randomly distorted structures. In addition to the 20 systematically distorted structures and the equilibrium structure, this gave us a total of 85 structures to be used in the fitting procedure.…”

Configuration and conformation of alfentanil hydrochloride. Conformational study by NMR and theoretical calculations

“…Recently, a twisted boat has been proposed as the most stable conformation for 4‐acetoxy‐4‐(3‐aryloxy‐1‐propynyl)‐1‐(2‐ethoxyethyl)piperidinium chloride, which is stabilized by intramolecular hydrogen bond between the oxygen in the N ‐substituent and the hydrogen on the N ‐atom and the oxygen on position 4 . Interestingly, N‐ or S‐oxides prefer to adopt conformations with the oxide occupying axial positions.…”

A convenient synthesis of diaryl methylphosphonates and transesterification products therefrom

“…These were run on a 0.5 molar scale. The Bis(p-chlorophenyl) Methylphosphonate (4). NMR signals were observed at r 8.24 (3 H, doublet, J = 17.5 Hz, CH3P) and 3.0-2.3 (8 H, multiplet, phenyl).…”

“…These are prepared according to standard procedures. 4 The singlet resonance for the olefinic proton is readily identified in the NMR spectrum. Relationship 1 + = 3.575h -29.6…”