Phosgene iminium salts

From dihalomethyleneiminium salts (phosgene iminium salts, PI salts)... 

Azirines and Aziridines.— The photolysis and thermolysis of the azido ester (143) to the azirine (144) was described by Hassner and Fowler in 1968. A study of isomeric compounds (145) has now been described, leading to the tautomeric isomer (146) of the antibiotic azirinomycin (147). 3,5-Dimethylaminoisoxazoles (148) have been prepared by the addition of hydroxylamine to phosgene iminium salts. The photoisomerization of the 4-substituted isoxazoles (148) to the azirines (149) is already known, and a paper has now described the near-quantitative thermal... 

Azetidiniminium salts - ° are available from the reaction of imines with iminium salts derived from tertiary carboxamides. These smoothly react with phosgene "- to yield a-chloroiminium... 

The reaction of V-cyanocarboximidamide with (chloromethylene)iniinium salts provides another important route to substituted 1,3,5-triazines.394,395 The (chloromethylene)iminium salts are prepared in situ from the corresponding amides, thioamides or dithiocarbamates and phosphoryl chloride, phosphorus pentachloride or phosgene (cf. Houben-Weyl, Vol. E5,... 

The synthesis of l,S-dichloro-l,S-dideoxypentitols by reaction of unprotected pentitols with Vilsmeier-Haack iminium salts or Viehe-Janouseck phosgene-based iminium salts, in a similar way to that previously reported (Vol. 26, p. 187, ref. 12 and Vol. 25, p. 202, ref. 20), has been described. A detailed H and C NMR analysis of the products is also described. ... 

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