| 摘要 |
Title cpds. of formula (I) are prepd. by ring closure of beta-chlorimmonium salts of formula (II) with thionoamides of formula (III): R-(CH=CH)n- =CH-CH-CH=NR circled positive 2 "' A circled negative (where R is H, alkyl, aryl or (substd) heteroaryl, R' is H, alkyl, aralkyl or (subsituted) aryl, NR2" is an aliphatic, cycloaliphatic, aliphatic-aromatic or heterocyclic secondary amine residue, NR2"' is any secondary amine function, A is a monovalent acid residue or the corresponding part of a polyvalent acid residue and n is 0,11 or 2) in an acid anhydride of a lower carboxylic acid in the presence of a basic cpd. at the boiling point of the acid anhydride the pyrylium salt is recovered by precipitation with a mixture of acetate and dialkyl ether. Cpds. (I) are components of organic dyes, e.g. cyanine dyes or intermediates for other heterocyclic cpds. |
