1-Hydroxybenzotriazole → (2R,4S)-(-)-N-[4-(dimethoxyphosphorylmethyl)phenyl]-1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

1-Hydroxybenzotriazole (HOBt) (0.51 g) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (0.69 g) were added to a solution of (2R,4S)-(−)-1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2-carboxylic acid (0.84 g) and dimethyl 4-aminobenzylphosphonate (0.65 g) in N,N-dimethylformamide (DMF) (10 ml) at 0° C. This mixture was stirred at 0° C. for 1 hour and at room temperature for 15 hours, after which it was poured into water and extracted with ethyl acetate-tetrahydrofuran (3:1). The ethyl acetate layer was washed successively with 1N HCl, water, a saturated sodium hydrogencarbonate solution, water and brine, and dried (MgSO4), after which the solvent was distilled off. The residual solid was collected by filtration, followed by recrystallization from ethanol-hexane to yield (2R,4S)-(−)-N-[4-(dimethoxyphosphorylmethyl)phenyl]-1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2-carboxamide (0.92 g, 64%). Colorless needles. Melting point 198-199° C. Optical rotation [α]D (23° C.) −198.8° (c=0.50, CHCl3).

Provenance & Evidence