N-Phenylglycine ethyl ester → (4aR-cis)-1,2,3,4a,5,10b-Hexahydro-5,5-dimethyl-3-oxo-1-phenyl[1]benzopyrano[3,4-b][1,4]oxazine-9-carbonitrile

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Reaction Steps

A solution of N-phenylglycine ethyl ester (900 mg, 5.0 mmol) in 1,2-dichloroethane (10 mL) under argon at 20° C. was treated with trimethylaluminum (3.0 mL, 2.0M in toluene, 6.0 mmol) over 1-2 minutes. After 15 minutes, (1aR-cis)-1a,7b-dihydro-2,2-dimethyl-2H-oxireno[c][1]benzopyran-6-carbonitrile (1.0 g, 5.0 mmol, title A compound of example 3) was added at once and stirring was continued for 1.5 hours. The mixture was diluted with ethyl acetate, quenched with a few drops of water and filtered through celite to remove gelatinous aluminum salts. The filtrate was washed with 5% sodium bicarbonate, water and brine, dried over anhydrous magnesium sulfate and concentrated. The residue was triturated with warm methanol to give warm methanol to give the title product (392 mg), mp 241°-243° C. [α]D =-129.1 ° (c=0.35 CHCl3). Analysis calculated for. C20H18N2O3 ·0.14 H2O: C,71.29; H,5.47; N, 8.31. Found: C, 71.05; H, 5.30; N, 8.55.

Provenance & Evidence