反应详情

温度

0 °C

To a solution of oxalyl chloride (23 ml) in dichloromethane was added dropwise dimethyl sulfoxide (374 ml) while keeping the temperature below -50° C. After the mixture was stirred for 30 minutes at -50° C.~-60° C., 1.2-bis(benzyloxycarbonyl)-4-(1-hydroxyethyl)pyrazolidine (675 g) was added dropwise below -50° C. After the mixture was stirred for 45 minutes at -50° C.~-60° C., triethylamine (122 ml) was added dropwise below -50° C. The reaction mixture was allowed to warm to 0° C. and quenched with water (500 ml). The aqueous layer was separated and extracted twice with dichloromethane (200 ml×2). The combined organic layer was washed with 1N hydrochloric acid (200 ml×2), saturated sodium bicarbonte (200 ml), and 5% sodium chloride (200 ml), dried over magnesium sulfate, and evaporated under reduced pressure. The residue was chromatographed on silica gel (820 ml, hexane:ethyl acetate=2:1~1:1) to give 1,2-bis(benzyloxycarbonyl)pyrazolidin-4-yl methyl ketone (61.5 g).

1. customthe temperature below -50° C
2. stirringAfter the mixture was stirred for 45 minutes at -50° C.~-60° C.
3. customquenched with water (500 ml)
4. customThe aqueous layer was separated
5. extractionextracted twice with dichloromethane (200 ml×2)
6. washThe combined organic layer was washed with 1N hydrochloric acid (200 ml×2), saturated sodium bicarbonte (200 ml), and 5% sodium chloride (200 ml)
7. dry with materialdried over magnesium sulfate
8. customevaporated under reduced pressure
9. customThe residue was chromatographed on silica gel (820 ml, hexane:ethyl acetate=2:1~1:1)