The novel reagents PhSeOTfâEt3N·3HF and PhSeSbF6âEt3N·3HF act as PhSeâF equivalents in the fluoroselenenylation of alkynes. Oct-4-yne, cycloundecyne and cyclododecyne, as well as the unsymmetrical alkynes PhâCCâMe and BuâCCâR (R = Me, Et, iPr and tBu) give the corresponding (E)-fluoro(phenylseleno)alkenes in preparative yields. The reagent PhSeOTfâEt3N·3HF gives a similar product composition of regioisomers to Ph2Se2âXeF2 in addition reactions to BuâCCâR. This is indicative of a similar reaction mechanism of the reagents. Probably a selenirenium ion acts as an intermediate. X-Ray single crystal structure analysis of (E)-1-fluoro-2-phenylselenocycloundecene confirms the trans-addition of [PhSeâF] to cycloundecyne.
新型试剂 PhSeOTfâEt3NÂ-3HF 和 PhSeSbF6âEt3NÂ-3HF 在
炔烃的
氟硒化反应中起着 PhSeâF 等价物的作用。八-4-炔、环十一炔和
环十二炔以及非对称
炔烃 PhâCCâMe 和 BuâCCâR (R = Me、Et、iPr 和 tBu)可以制备出相应的(E)-
氟(苯基
硒)烯。在与 BuâCCâR 的加成反应中,试剂 PhSeOTfâEt3NÂ-3HF 与 Ph2Se2âXeF2 产生了相似的区域异构体产物组成。这表明这两种试剂的反应机理相似。可能是
硒离子作为中间体起了作用。(E)-1-
氟-2-苯基
硒环
癸烯的 X 射线单晶结构分析证实了 [PhSeâF] 与环
癸烯的反式加成反应。