Aziridinations imines

SULFURIZATIONAND SULFURCm ORINATION] (Vol23) -reaction with aziridine [IMINES, CYCLIC] (Vol 14)... 

Under conditions similar to those already outlined, stable aziridin imine derivatives, e.g. (422) and (423), can be prepared in excellent yields (70-80%) by treating the appropriate a-bromoamidines (easily accessible from the amide precursor) with potassium t-butoxide in ether <70AG(E)38l). At low temperatures the elimination proceeds with high regio- and stereo-selectivity at -40 °C (421) yields predominantly (422). 

In the photolysis of methyl-(3,5,5-trialkyl-3,5-dihydro-[l,2,3]triazol-4-ylidene)-amine (34) in solution, aziridine imines are formed quantitatively, about 85% on the non-least-motion path and 15% on the least-motion path (90CB2195). The gas-phase pyrolysis of 34 affords only the product of the former path (93CB2683). 

Triazoline ring cleavage with nitrogen expulsion can be achieved by photolysis or thermolysis and leads to aziridines, imines, or the isomeric enamines.12 In contrast to thermolysis where product mixtures are obtained, photolysis is more selective and aziridine is the major product.27,79,2 2-290... 

In principle, elimination of nitrogen from A -l,2,3-triazolines yields aziridines, imines or isomeric imines as shown in Scheme 10. 

The reactions of aziridine bearing an imino group at C(2) (aziridine imines) have been reviewed . 

Photochemically induced ring contraction of novel 4-iminodi-hydro-1,2,3-triazoles to the corresponding ( )- and (Z)-aziridin-imines has also been reported. A different pathway is followed in the 6-(l -triazolyl)uracils (24) which on irradiation in acetonitrile were converted into the pyrrolo[2,3-d]pyrimidines (25) via triplet biradical intermediates a novel cyclisation leading to the formation of pyrimido[4,5-c]isoquinolines is observed, however, when C-5 phenyl substituents are present on the triazole ring. Rate constants for the cycloaddition f diarylnitrilimines, generated by photoelimination of nitrogen from diaryl 2H-tetra-zoles, to various dipolarophiles have been determined experiment-... 

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