Synthesis of CF3-Substituted Olefins by Julia-Kocienski Olefination Using 2-[(2,2,2-Trifluoroethyl)sulfonyl]benzo[d]thiazole as Trifluoromethylation Agent

A modified Julia–Kocienski protocol was investigated for the synthesis of CF3‐substituted terminal olefins. By employing a simple one‐step procedure, aldehydes were converted into the corresponding CF3‐substituted olefins using 2‐[(2,2,2‐trifluoroethyl)sulfonyl]benzo[d]thiazole as the trifluoromethylation agent. This sulfone was prepared on a gram scale in two steps from inexpensive and commercially available trifluoroethanol. The Julia–Kocienski olefination tolerated various functional groups, and the trifluoromethylated olefins were obtained in good yields. However, the E/Z selectivity was strongly substrate dependent, and only moderate selectivities could be achieved. By employing a two‐step procedure, it was possible to synthesize an α‐trifluoromethyl‐substituted sulfone on a gram scale by starting from inexpensive and commercially available trifluoroethanol. This substrate could then be used in a modified Julia–Kocienski olefination to prepare trifluoromethyl‐substituted terminal olefins).