Convenient Preparation of 1,3-Bis(dimethylamino)trimethinium Perchlorate, Tetrafluoroborate and Hexafluorophosphate

Abstract

Formylation of ethyl vinyl ether with (chloromethylene)dimethylammonium chloride prepared from dimethylformamide and oxalyl chloride or phosgene followed by successive treatment with dimethylamine and 70% perchloric acid leads to 1,3-bis(dimethylamino)trimethinium perchlorate 1a in high yield. Similarly, work-up of the reaction mixture after formylation with hexafluorophosphoric acid or dimethylamine tetrafluoroborate afforded 1,3-bis(dimethylamino)trimethinium hexafluorophosphate 1b or tetrafluoroborate 1c, respectively.