| Abstract
| - The preparation of 3,3-difluoro-6-methylhept-5-en-2-one 1, a key intermediate for the synthesis of4,4-difluoroterpenes, and applications in linalool and geraniol series are described. The processinvolves 1,1-difluoro-2-trimethylsilyoxypropene, an enol silyl ether prepared from acetyltrimethylsilane and trifluoromethyltrimethylsilane, and its reaction in situ with prenyl benzoate, undercatalysis by trimethylsilyl trifluoromethanesulfonate. Optimized conditions leading to either thedesired enol silyl ether or the unprecedented methyl(trifluoromethyl)trimethylsilyl carbinol 4 havebeen achieved. The prenylation of the enol silyl ether gives a 9/1 mixture of regioisomers, in favorof the expected ketone 1. Treatment of 1 with vinylmagnesium bromide leads to (±)-4,4-difluorolinalool 7. Reaction with the lithium enolate of ethyl diethylphosphonoacetate, and thenLAH reduction, converts 1 to 4,4-difluorogeraniol 11, with complete stereoselectivity.
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