New Heterocyclic Betaines

Article abstract of DOI:10.1021/jo00193a052

Several new types of cross-conjugated, heterocyclic betaines have been prepared from (chlorocarbonyl)phenylketene and e.g., 1-methylimidazole and pyridine; in an alternative synthetic approach, reaction of 1-(substituted acetyl)-3,5-dimethylpyrazole with NaH and the electrophilic reagents phosgene, thiophosgene, and other activated geminal dichlorides allowed variation of the exocyclic substituents in new examples of the pyrazolo<1,2-a>pyrazole system.