Abstract: The novel preparation of 2-(trifluoromethyl)-2-propenal 5 is described. First, 2,2-dimethyl-4H-1,3-dioxan-5-ol 2 was generated from commercially available 2,2-dimethyl-4H-1,3-dioxan-5-one 1. Subsequent conversion to the tosylate 3, followed by elimination using potassium 2-methyl-2-octanoxide generated the desired 5-(trifluoromethyl)-2,2-dimethyl-4H-1,3-dioxin 4. The synthesis proceeded in an overall yield of 32% to readily afford gram quantities of 4. The subsequent thermal retrocycloaddition to generate 5 was demonstrated to be quantitative by 1H NMR although it was not isolated. Work is ongoing to demonstrate the synthetic versatility of enal 5 in cycloadditions, 1,3-dipolar additions, and alkylation chemistry.
