关键词: 次磺酰胺, 高价碘(III)试剂, 氟烷基化反应, 硫亚胺, 化学选择性

Both trifluoroethyl and sulfilimine groups are two important classes of pharmacophores and structural motifs, widely present in numerous biologically active molecules. However, methods for simultaneously introducing these two skeletons into molecules remain very limited. This study developed a metal-free synthetic strategy that enabled a base-promoted sulfur-trifluoroethylation reaction between sulfenamides and hypervalent iodine(III) reagents at room temperature under ambient air, providing structurally diverse trifluoroethyl sulfilimine derivatives in moderate to good yields. The optimization studies revealed NaOAc as the preferred base and 1,2-dichloroethane (DCE) as the optimal solvent. After that, the substrate scope and generality of sulfenamides for this metal-free reaction was evaluated. In general, sulfenamides bearing electron-donating, electron-withdrawing aryl groups and heteroaryl, alkyl substituents are well-tolerated. Furthermore, pentafluoropropyl hypervalent iodine(III) reagents were also compatible with this reaction, allowing for the efficient synthesis of pentafluoropropyl sulfilimine compounds. The successful large-scale reaction and downstream transformation of the product demonstrated the potential synthetic utility of this strategy. On the basis of experimental results and literature reports, a plausible mechanism for this reaction was presented. Overall, this method avoids the use of transition metals and offers advantages such as readily available starting materials, mild conditions, operational simplicity, and good functional group tolerance, providing a novel approach for the synthesis of fluoroalkyl sulfilimine derivatives. The general procedure for this base-promoted sulfur-fluoroalkylation reaction is as follows: To a 10 mL reaction flask with a magnetic stir bar, sulfenamide (0.2 mmol), base (0.4 mmol), hypervalent iodine(III) reagent (0.4 mmol) and DCE (2 mL) were sequentially added. The reaction mixture was stirred at room temperature under air atmosphere for 24 h. After completion of the reaction monitored by thin-layer chromatography (TLC) analysis, the reaction mixture was concentrated by vacuum and the residue was purified by column chromatography on silica gel (petroleum ether/ethyl acetate=2∶1, V∶V) to yield the corresponding product.

Key words: sulfenamides, iodine(III) salts, fluoroalkylation, sulfilimines, chemoselectivity