Chemistry of polyhalogenated nitrobutadienes, part 11: Ipso-formylation of 2-chlorothiophenes under Vilsmeier-Haack conditions

摘要

The regioselective ipso-formylation of electron-rich, 3,4-push-pull- substituted 2-chlorothiophenes under Vilsmeier-Haack conditions was performed in good yields. The synthetic scope of this new reaction was explored using various halothiophenes, chloroanilines, and 1-methyl-3-chloroindole. In comparison with their structural C-H analogs the chlorinated thiophenes, anilines, and the indole proved to be less reactive toward electrophilic attack by chloromethyleniminium salts.