Chloromethyliminium salts

The condensation of A-cyanoamidines (517) with chloromethyliminium salts (516), prepared in situ from amides R C0NR2R3 + PC13, provides an efficient, convenient route to many 1,3,5-triazines (80S841, 81AJC623). For R2 and R3 = alkyl, the chloro-1,3,5-triazines (518 R5 = C1) are produced. However, for R2 = aryl, the amino derivative (518 R5 = NR2R3) may become the major product. 

Triazines with three different substituents are formed by variations on the above methods. There is no efficient route to trialkyl or triaryl derivatives, although the reaction of acylimidates and amidines has met with some success (see Section 2.20.4.6.2). In general the best routes available are as follows, (a) Substitution reactions of cyanuric chloride, (b) The condensation of Af-cyanoamidine with chloromethyliminium salts, (c) 2-Aryl-1,3,5-triazin-2-ones may be efficiently prepared by ring closure reactions on AT-(a-chloroalky-lidene)carbamoyl chloride and amidines (see Section 2.20.4.4.1). 

Vilsmeier-Haack formylation Synthesis of substituted benzaldehydes and heteroaromatic aldehydes using chloromethyliminium salts. 468... 

Amides react readily with POCI3 to generate a chloromethyliminium salt this itself is a potent electrophile, and reacts with aromatic compounds by an electrophilic aromatic substitution (SfAn) reaction. 

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