Hydroxylamines reaction with, phosgene

The imonium salt (199), obtained from ynamines and phosgeneimonium chloVide, underwent ready reaction with monosubstituted hydrazines to give the 3,5-bis(dimethyl-amino)pyrazole (200) (68T4217, 69T3453). Similarly, the adduct (201), resulting from the addition of phosgene to ynamines, likewise reacted with sym-disubstituted hydrazines to give pyrazoles (202). With hydroxylamine derivatives the isoxazolinone (203) was obtained. 

N-Hydroxyphthalimide alkali or trialkylammonium salt allowed to react at -5 to 0° with excess phosgene in methylene chloride or GGI4 o-chloroformyl-hydroxylamine derivative. Y 92%. F. e. and reactions, e.g. use in peptide synthesis, s. H. Gross and L. Bilk, Ang. Ch. 79, 532 (1967). 

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