Precise Construction of SCF2H or SeCF2H Groups on Heteroarenes Generated in Situ from CF3-Containing 1,3-Enynes

A divergent strategy for precise construction of SCF2H or SeCF2H groups on heteroarenes generated in situ from CF3-containing 1,3-enynes was developed. Reactions of readily available 1,3-enynes with S-8 and ClCF2H provided 3-SCF2H-4-CF3-thiophenes via a cascade thiophene construction/selective C3 position thiolation/difluoromethylthiolation process, as did a series of 3-SeCF2H-4-CF3-selenophenes by similar strategies. The plausible radical annulation process for the construction of the thiophene ring and difluorocarbene generated in situ was confirmed by experiment.