Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
J Org Chem. 2020 Aug 7;85(15):10098-10109. doi: 10.1021/acs.joc.0c01355. Epub 2020 Jul 20.
A metal- and oxidant-free photoinduced strategy for thioxo sulfur-selective trifluoromethylation of β-ketodithioesters at room temperature is reported. Excellent /-stereoselectivity has been achieved with cheap and viable Langlois' reagent (CFSONa, sodium triflinate) in the presence of eosin Y, which acts as a hydrogen atom transfer (HAT) catalyst. The reaction proceeds disulfide intermediate disulfanediylbis(3-(alkylthio)-1-phenylprop-2-en-1-one) (a dimer of β-ketodithioester) followed by complementing proton-coupled electron transfer-mediated reverse HAT cycle of eosin Y. This operationally simple and efficient protocol allows direct access to triflinated α-oxoketene dithioacetals in good to excellent yields bearing diverse synthetically useful functional groups of different electronic and steric nature.
本文报道了一种在室温下无需金属和氧化剂的光诱导策略，实现了β-酮二硫酯的硫代选择性三氟甲基化。在曙红 Y 的存在下，廉价且可行的朗格洛伊斯试剂（CFSONa，三氟甲磺酸纳）可以实现优异的立体选择性，曙红 Y 作为氢原子转移（HAT）催化剂。该反应经历二硫键中间体二硫二亚乙基双（3-（烷基硫代）-1-苯基-2-烯-1-酮）（β-酮二硫酯的二聚体），然后通过补充质子耦合电子转移介导的曙红 Y 的反向 HAT 循环。这种操作简单、高效的方案允许直接以良好到优异的产率获得带有不同电子和空间性质的各种合成有用官能团的三氟甲硫基-α-氧代烯酮二硫缩醛。
