反应详情

温度

-40 °C

A solution of tartaric acid bis(acetonide) prepared as in Example 1 (1.84 g, 8.0 mmol) in anhydrous tetrahydrofuran (15 mL) was cooled to −40° C. A 1 M solution of potassium tert-butoxide in tetrahydrofuran (8.0 mL, 8 mmol) was added by syringe over the course of 5 min. The mixture was stirred an additional 20 min. at −40° C. after which 4 M HCl in dioxane (3.0 mL, 12 mmol) was added and the reaction was allowed to warm. Ethyl acetate (75 mL) and 1 N HCl (25 mL) were added. The organic layer was separated and washed with water (25 mL). Removal of volatiles on the rotary evaporator afforded the crude product (1.37 g, 99%). This material contained ca. 5% of a side-product presumed to be the E-stereoisomer and characterized by an NMR singlet at δ 5.48 as well as ca. 10% of recovered bis(acetonide) starting material. A 0.63 g sample of this material was crystallized from hot ethyl acetate to afford Z-2,2-dimethyl-5-carboxymethylene-1,3-dioxolan-4-one as fine white needles (0.37 g).

1. additionwas added
2. temperatureto warm
3. customThe organic layer was separated
4. washwashed with water (25 mL)
5. customRemoval of volatiles
6. customon the rotary evaporator
7. customafforded the crude product (1.37 g, 99%)
8. customA 0.63 g sample of this material was crystallized from hot ethyl acetate