toluene-4-sulfonic acid in benzene 2 h; Heating;

1: 5-isobutylidene-2,2-dimethyl-[1,3]dioxan-4-one; (trifluoromethyl)-trimethylsilane With sodium acetate in N,N-dimethyl-formamide T=50°C; 2 h; Inert atmosphere; 2: With hydrogenchloride in water; N,N-dimethyl-formamide T=120°C; 1 h; Inert atmosphere; 3: benzyl bromide With potassium carbonate in N,N-dimethyl-formamide T=20°C; 2 h; Inert atmosphere;