On the Reaction of Acylium Salts with Isocyanates

Article abstract of DOI:10.1002/prac.19953370182

Alkyl isocyanates (3) react with acylium salts (2) in a 2:1 ratio to furnish 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium salts 4.These cyclic N-acyliminium salts are decomposed with catalytic amounts of water to give either oxadiazinium salts 5 or pyrimidinium salts 7.With aqueous base compounds 4 are transformed into acylureas 6.Hetero substituted open chain N-acyliminium slats (8a, 11c, 12c, 13f, 15g, 16a) are produced from 4 by treatment with heteronucleophiles such as methanol, p-anisidine, p-cresol, thiophenol, 1,3-dimethylurea, or benzohydrazide, respectively.Excess of nucleophile furnishes further degradation products of 4, e.g. oxonium salts (9a) and iminium salts (14f).