Methanol → Costatolide

Temperature

-78 °C

To a solution of (-)-calanolide A (341 mg, 0.922 mmol) in anhydrous methylene chloride (5 mL) at -78° C. under N2 was added a solution of diethylamidosulfur trifluoride (DAST, 178 mg, 1.11 mmol) in methylene chloride (1 mL) and the resulting yellow solution stirred at -78° C. for 4 hours. The reaction was quenched with 0.5 mL methanol, then allowed to warm to room temperature. The solution was diluted with methylene chloride (20 mL), then washed with water (50 mL) and saturated brine (50 mL). After drying over magnesium sulfate, the solution was filtered and evaporated to provide a light yellow solid. TLC analysis (silica gel, 3% methanol in methylene chloride) showed two components, one fast-moving and one slow. The material was chromatographed through 80 g silica gel, eluting with 1% methanol in CH2Cl2, and the fractions containing the respective components combined and evaporated to afford 198 mg (61% yield) of compound 22 and 75.3 mg (22%) of (-)-calanolide B.

1. customThe reaction was quenched with 0.5 mL methanol
2. temperatureto warm to room temperature
3. additionThe solution was diluted with methylene chloride (20 mL)
4. washwashed with water (50 mL) and saturated brine (50 mL)
5. dry with materialAfter drying over magnesium sulfate
6. filtrationthe solution was filtered
7. customevaporated
8. customto provide a light yellow solid
9. customThe material was chromatographed through 80 g silica gel
10. washeluting with 1% methanol in CH2Cl2
11. additionthe fractions containing the respective components
12. customevaporated

ORD record

ord-3803e71433fa48f088764d2e83a0f801

Source dataset

uspto-grants-1999_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05859050