摘要
二氟卡宾在有机氟化物的合成中发挥了重要作用.之前的发现,二氟卡宾能与硫单质反应产生硫代氟光气,这对二氟卡宾化学的新发现以及硫代氟光气的应用研究都具有重要价值.利用这一路径已经实现了端基炔烃和烷基卤化物的三氟甲硫基化.在此,继续深入研究这一路径在合成上的应用,并实现了芳基和烯基碘化物的三氟甲硫基化.三氟甲硫基化是有机氟化学的一个重要研究方向,常用方法一般需要使用含CF3S基团的昂贵试剂.在该方法中,CF3S基团是由二氟卡宾、硫单质和氟离子现场产生的,所用试剂都廉价易得.
Abstract
Difluorocarbene has found widespread applications in the synthesis of fluorine-containing molecules.We have previously found that difluorocarbene can react with elemental sulfur to produce thiocarbonyl fluoride,which is of great val-ue for the new discoveries of difluorocarbene chemistry and the investigations of synthetic utilities of thiocarbonyl fluoride.We have developed the transformation of difluorocarbene into thiocarbonyl fluoride as a synthetic tool to achieve trifluoro-methylthiolation of terminal alkynes and alkyl halides.In continuation of our research interest in this chemistry,herein we further apply the difluorocarbene transformation to the trifluoromethylthiolation of aryl and alkenyl iodides.Trifluorome-thylthiolation is an active research area in organofluorine chemistry,and the commonly used trifluoromethylthiolation meth-ods usually require the use of expensive CF3S-containing reagents.In contrast,in our protocol the CF3S group is generated in situ from difluorocarbene,elemental sulfur and a fluoride anion,all of which are cheap and easily available reagents.The general experimental procedure is shown as follows.Into a 5 mL sealed tube were added 4-phenyl phenyl iodide(1a,56.0 mg,0.2 mmol),S(57.8 mg,1.8 mmol),Ph3P+CF2CO2-(PDFA)(213.8 mg,0.6 mmol),AgF(0.5 mmol,63.4 mg),ligand L1(0.6 mmol,158.9 mg),CuI(76.2 mg,0.4 mmol),and dioxane(1.0 mL)under a N2 atmosphere.The reaction mixture was stirred at 110 ℃ for 8 h.After the reaction system was cooled to room temperature,Et3N(0.5 mL)was added to remove the excess elemental sulfur by a redox reaction(the final product would be contaminated by elemental sulfur if elemental sulfur was not removed).The mixture was diluted with 10 mL of saturated brine,and then the product was extracted with ethyl ace-tate.The combined organic layers were washed with brine,dried over sodium sulfate,and concentrated to 1 mL.The residue was subjected to flash column chromatography to afford the pure product.
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