反应详情

2-Bromo-2-nitro-1,3-propanediol (0.02 m) and malonaldehyde bis (dimethyl acetal) (3.3 ml, 0.02 m) were heated, under nitrogen, in an oil bath at 96° C. Toluene sulfonic acid monohydrate (50 mg) was added after the solid melted. The reaction flask was sealed with a rubber septum and returned to the bath. Every 10 minutes the flask was flushed for one minute with a vigorous nitrogen stream to remove methanol. After 2 hours the brown viscous oil was cooled and subsequently solidified. The dark oily solid was treated with 20 ml of boiling hexane. The hot light yellow hexane solution was decanted from an insoluble black tar. Upon cooling to room temperature a slightly yellow solid crystallized out. The solid was collected and washed with hexane to give 5-bromo-5-nitro-2-(2',2'-dimethoxyethyl)-1,3-dioxane (3.5 g) m.p. 95°-97° C. A sample recrystallized from methanol melted at 96°-98° C.

1. customThe reaction flask was sealed with a rubber septum
2. customEvery 10 minutes the flask was flushed for one minute with a vigorous nitrogen
3. customto remove methanol
4. temperatureAfter 2 hours the brown viscous oil was cooled
5. additionThe dark oily solid was treated with 20 ml of boiling hexane
6. customThe hot light yellow hexane solution was decanted from an insoluble black tar
7. customcrystallized out
8. customThe solid was collected
9. washwashed with hexane