反应详情

To 300 mL toluene in an 500 mL flask with condenser under a nitrogen atmosphere were added 30 g (120 mmol) di(trimethylolpropane), 4, 45.6 mL (38.9 g, 300 mmol) acrolein diethyl acetal, and 1.5 g (6 mmol) pyridinium p-toluenesulfonate. The mixture was refluxed for 4 hours, then cooled to room temperature, and 0.67 g (6 mmol) potassium tert-butoxide added. The toluene was removed by evaporation under reduced pressure, and the residue distilled in a Kugelrohr apparatus (pressure 1-3 mbar, pot temperature 142-180° C.) to give 35.35 g (91% yield) of crude di[(5-ethyl-2-vinyl-[1,3]dioxan-5-yl)methyl]ether, 5, as a light yellow oil. The crude product, 30 g, was purified by chromatography on 1 Kg Merck Silica Gel 60 in a 2 L glass fritted funnel, eluting with 20:80 ethyl acetate/heptane, to give 27.8 g (71% yield) of purer product, which was re-purified by a second chromatography on 1 Kg MERCK® Silica Gel 60 in a 2 L glass fritted funnel, eluting with 10:90 ethyl acetate/heptane, to give 16.44 g (42% yield) of essentially pure di[(5-ethyl-2-vinyl-1,3dioxan-5-yl)methyl]ether. This material was used in the photoisomerization.

1. temperatureThe mixture was refluxed for 4 hours
2. customThe toluene was removed by evaporation under reduced pressure
3. distillationthe residue distilled in a Kugelrohr apparatus (pressure 1-3 mbar, pot temperature 142-180° C.)