The Stereoselective Synthesis and the Nitrogen Interconversion Studies of 2-(tert-butoxymethyl)-1-[NT-(4-methylbenzenesulfonyl) (4-methylphenoxy) imidoyl] aziridine

Abstract

Aziridines are very important precursors to a wide range of biologically active molecules such as amino acids, antibiotics, alkaloids, and many others. 1 The two most important aspects of this class of compounds have been the stereo-regio-selectivity of their synthesis and energy barrier of nitrogen inversion. 1-3 Both aspects have very important effects on their physical and/or chemical behaviours. Lwowski and co-workers reported a highly stereoselective synthesis of aziridines via a reaction of imidoyl nitrene with olefines. 4 Dabbagh and coworkers reported that certain imidoyl nitrenes are known to have moderate reactivity with higher selectivity. 5,6 Recently, Atkinson and co-workers have described the preparation of range of aziridines via reagent-controlled diastereoselective aziridination of alkenes using 3-acetoxyaminoquinazolinones. 7 They further reported the acid-catalysed aziridine ring-opening with retention of configuration. Furthermore, the interconversion of the isomers on nitrogen of nitrogen-containing organic compounds has been the cornerstone of research interests for the last half century. 2,8 Generally, the rapid nitrogen inversion of ordinary amines focused the attention on aziridine with its much lower inversion rate, because of strain in the three member ring. 2,9 The aziridines' nitrogen inversion has been investigated in detail. 2,3,9

Dynamic 1H NMR Study of the Barrier to Rotation about the C−N Bond in Primary Carbamates and Its Solvent Dependence

“…NMR measurements, both in the gas phase and in solution, have shown that the rotational barrier in amides is strongly affected by the medium. ,,− ,− Nevertheless, a different behavior was observed for tertiary carbamates if studied by dynamic NMR spectroscopy in solution: Actually, it has been found that the rotational barrier proved to be apparently insensitive to the solvent polarity. − Recently, we reported dynamic 1 H NMR spectroscopy studies of various carbamates and other nitrogen-containing organic compounds. ,− …”

“…The rate constants, k , for the present dynamic process in the carbamates 1a − d were calculated at the coalescence temperature ( T c ) employing the Gutowsky−Holm equation ( k c = πΔν/2 -1/2 ). ,,,,, Assuming the transmission coefficient, κ, to be unity, the free energies of activation (Δ G ⧧ ) were calculated according to the Eyring equation (Δ G ⧧ = RT c [ln T c − ln k c + 23.76]). ,,,,, …”