Water → (4R)-3,5,5-Trichloro-4-hydroxycyclopent-2-en-1-one

The (1R,4R)-acid (4) (200 mg, 0.8 mmol) was added portionwise over 10 min to lead tetraacetate (500 mg, 1.13 mmol) in acetic acid (5 ml) containing water (0.05 ml) at 80°. After a further 5 min, water (25 ml) was added and the cooled mixture extracted with ether (3×25 ml). The combined ether solutions were extracted with 5% aqueous sodium bicarbonate until the washings were alkaline (pH 7.5-8), then washed with water (10 ml), dried (MgSO4), and evaporated under reduced pressure. Short path distillation (bath temp. 60°/0.1 mmHg) gave the (4R)-enone (6) (160 mg, 98%) as a colourless oil, [α]35725 +1547° (c 5.66×10-2, EtOH) [α]25225 -11,280° (c 2.26×10-3, EtOH), [θ]33325 +8407° (c. 5.66×10-2,EtOH), [θ]24025 -45,025° (c 2.26×10-3, EtOH) (Found : C, 29.8; H, 1,65; Cl, 51.3; C5H3Cl3O2 requires C, 29.8; H, 1.5; Cl, 52.8%).

1. extractionthe cooled mixture extracted with ether (3×25 ml)
2. extractionThe combined ether solutions were extracted with 5% aqueous sodium bicarbonate until the washings
3. washwashed with water (10 ml)
4. dry with materialdried (MgSO4)
5. customevaporated under reduced pressure
6. distillationShort path distillation (bath temp. 60°/0.1 mmHg)

ORD record

ord-aa3887f39ceb423687d3f8a2dd56ac4b

Source dataset

uspto-grants-1987_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04703127