Reactions of Nitrile Oxides and Nitrile Imines with Derivatives of 4,5-Dihydrooxazole and 4,5-Dihydrothiazole and with Related Compounds

Article abstract of DOI:10.1039/P19940003563

2-Phenyl-4,5-dihydrooxazole 4 gives a cycloadduct 6 when treated with benzonitrile N-oxide; with a 1-oxoalkene- or α-oxoarene-nitrile N-oxide (RCOCNO), an open chain product, RCO2CH2N(CN)COPh , is obtained.The six-membered-ring analogue of compound 4 undergoes similar reactions.Depending on the nature of the ring substituents, a substituted 4,5-dihydrooxazole reacts with a C,N-diarylnitrile imine, to give either a cycloadduct, e.g. 17, or a 1,2,4-triazol-4-ium salt, e.g. 19.The product from the reaction of 4,5-dihydro-2-methylthiazole 1b with a nitrile imine depends upon the nature of the C- and N-substituents in the latter.In all cases it is postulated that a 4-substituted triazolium salt 24 is formed.This may lose thiirane to give a substituted 1,2,4-triazole 25, or it may react with a second molecule of the precursor of the nitrile imine, to give a 4-substituted 1,2,4-triazolium salt, e.g. 27, in which the precursor moiety is incorporated into the C-4 side chain.

Full text of DOI:10.1039/P19940003563

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