An efficient stereoselective preparation of cis-perfluoroalkenylzinc reagents [(E)-RFCFCFZnCl] by the metallation of 1H,1H-perfluoroalkanes and their derivatization to cis-1-arylperfluoroalkenes [(Z)-RFCFCFAr]

Various 1H,1H-perfluoroalkanes (RFCF2CH2F, RF = CF3, C2F5, C4F9, C5F11, C6F13, C10F21) were metallated using LDA in a THF solution of ZnCl2 at RT or −78 °C to produce the corresponding perfluoroalkenylzinc reagents (RFCFCFZnCl) in a cis-selective fashion. An increased yield (75–83%) and cis-selectivity (>89%) of the perfluoroalkenylzinc reagents were observed for metallation reactions performed at −78 °C. The cis selectivity was excellent for 1H,1H-perfluoroalkanes with larger RF groups (C4F9, C5F11, C6F13, >96%). The cis-perfluoroalkenylzinc [(E)-RFCFCFZnCl] reagents were coupled with aryl iodides to obtain cis-1-arylperfluoroalkenes [(Z)-RFCFCFAr] in 71–95% isolated yields. The cis-perfluoroalkenylzinc reagents upon iodinolysis produced cis-1-iodoperfluoroalkenes [(E)-RFCFCFI] in 68–70% isolated yield.

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