Ammonia → (r)-8-Fluoro-3-(n-isopropyl-n-propylamino)-5-methoxy-3,4-dihydro-2h-1-benzopyran

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Reaction Conditions

Reaction Steps

(R)-8-Bromo-3-(N-isopropyl-N-propylamino)-5-methoxy-3,4-dihydro-2H-1-benzopyran (2.3 g, 6.72 mmol) was dissolved in anhydrous THF (25 mL) and cooled to -78° C. To this was a 1.6M n-BuLi solution (4.83 mL, 7.73 mmol) added dropwise and allowed to stir at -78° C. for 1 h. N-Fluorobenzenesulfonimide (2.55 g, 8.06 mmol), dissolved in anhydrous THF (15 mL), was added dropwise under 20-30 min and allowed to stir at -78° C. for 4 h. The reaction was stopped by adding 1 mL of a saturated aqueous NH4Cl solution followed by 3 mL of a solution comprised of 2 g of NH2OHxHCl and 8 g of Na2CO3 in 100 mL of H2O and allowing the reaction to warm to room temperature. A 2M NH3 solution was added and the reaction was extracted, twice, with diethyl ether, treated with brine, dried (Na2SO4), filtered, and evaporated in vacuo to give the crude product. Chromatography on silica (eluent: chloroform) gave 1.0 g (53% yield) of the title compound as a clear oil. [α]21D =-89.2° (C=0.1 CHCl3) GC-MS (70 eV) M=281 (32%).

Provenance & Evidence