Hydrochloric Acid → N-(6-Cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)-a-hydroxybenzeneacetamide

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To a solution of R-(-)-mandelic acid (22.1 g, 0.14 mole) and 1-hydroxy-benzotriazole hydrate (19.6 g, 0.14 mole) Cooled to 0° C. was added successively N-methylmorpholine (16.2 g, 0.16 mole), 4-amino-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran (29.4 g, 0.14 mole, from Example 8, part D) and 1-(3 -dimethylaminopropyl)-2-ethylcarbodiimide.HCl (27.9 g, 0.14 mole), The reaction mixture was stirred 0.5 hours at 0° C. and two hours at room temperature. The solvent was recovered under vacuum and the residue was partitioned between 5% aqueous HCl and ethyl acetate. The organic fraction was washed with saturated sodium bicarbonate solution, saturated sodium chloride solution, dried over magnesium sulfate and evaporated in vacuo to obtain 52 g of yellow gum. The crude diastereomer mixture was chromatographed on silica eluting with 1:1 hexane/ethyl acetate to obtain 19.8 g (40.6%) of Isomer B (isomer A being subject of Example 19 , part A); m.p.=135°-136° C., [α]D25 =-60.8°. 1H NMR (CDCl3) δ7.51-7.30 (m, 6H), 7.27 (d, J=1.76 Hz, 1H), 6.80 (m, 2H), 5.18 (m, 1H), 5.08 (d, J=2.93 Hz, 1H), 3.97 (d, J=2.93 Hz, 1H), 2.12 (dd, J=6.15 and 13.19 Hz, 1H), 1.69 (dd, J=11.43 and 13.20 Hz, 1H), 1.40 (s, 3H), 1.30 (s, 3H); 13C NMR (CDCl3) δ172.59, 157.53, 139.13, 133.07, 132.81, 131.98, 128.92, 126.38, 122.86, 118.97, 118.56, 103.25, 76.83, 74.26, 41.81, 38.96, 29.15, 24.62; MS: (M+H)+ @337.

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