Vilsmeier cyclization of α-acetyl-α-aroyl ketene-N,S-acetals: direct and efficient synthesis of halogenated pyridin-2(1H)-onesElectronic supplementary information (ESI) available: Experimental procedures, analytical data, and spectra copies of all compounds. CCDC 974611. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ra14626c

An efficient synthetic route to 3-aroyl-5-formyl-4-halo pyridin-2(1 H )-ones has been developed via Vilsmeier cyclization of 2-(ethylthio(arylamino)methylene)-1-alkylbutane-1,3-dione. The synthetic protocol has demonstrated the first example of Vilsmeier cyclization of α-acetyl-α-aroylketene- N , S -acetals, providing a novel route to 4-bromo/chloro pyridin-2(1 H )-ones. An efficient synthetic route to 3-aroyl-5-formyl-4-halo pyridin-2(1 H )-ones has been developed via Vilsmeier cyclization of 2-(ethylthio(arylamino)methylene)-1-alkylbutane-1,3-dione.