Diazetidines inversion

Diazetidines applications, 7, 483 electrophilic reaction, 7, 460 nitrogen inversion, 7, 10 nucleophilic reactions, 7, 462 photochemical reactions, 7, 456-457 reductive cleavage, 7, 465 spectroscopy, 7, 451-454 structure, 7, 451... 

Nuclear magnetic resonance (NMR) spectroscopy has been used extensively to study the conformation of a number of diazetidines, their thermodynamic stability, and kinetics of inversion at the N-center in addition to the routine structural elucidation. 

A detailed account of the use of H-NMR for the measurement of A(f, the barrier of inversion at the N-center, etc., have been described in GHEC-II(1996) <1996CHEC-II(1B)911>. Only a few salient features have been covered in this. Proton NMR has been used for the structural elucidation and to study the geometrical isomerism of a number of diazetidines and their derivatives. For example, H-NMR has been used to study the inversion of (Z,Z)-isomers and (A, )-isomcrs of 1,2-diazetidines 46. 

F-NMR has been used to measure the free energy of activation for the nitrogen inversion of l,2-bis(trifluoro-methyl)-3,4-tetrafluoro-l,2-diazetidine 48, which has been found to be 7.25 kcal mol 1 (30.3 kj mol ). 

The calculation of AG for the inversion at N-l of iV,iV-diary- or dibenzyl-substituted l,2-diazetidine-3-one has been carried out through 1 Il-NMR measurement <1970TL3605>. 

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