Benzyl isocyanate → N-(6-Cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)-N'-(phenylmethyl)urea

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Reaction Steps

A solution of (-)-4-amino-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran (2.0 g, 9.9 mmole, from Example 19, part B) and benzyl isocyanate (1.32 g, 9.9 mmole) in ethanol (15 ml) under argon was heated at reflux for two hours. The solvent ws recovered under vacuum and the crude product was triturated with isopropyl ether to obtain 2.98 g (89.7%) of the title compound as a pure white solid. m.p.=140-141° C., [α]D25DMF=-41.2°. 1H NMR (DMSO-d6) δ 7.59 (s, 1H), 7.56 (d. J=1.76 Hz, 1H), 7.38-7.22 (m, 5H), 6.89 (d, J=8.21 Hz, 1H), 6.56 (t, J=5.87 Hz, 1H), 6.49 (d, J=8.79 Hz, 1H), 4.94 (m, 1H), 4.30 (d, J=5.87 Hz, 1H), 2.11(dd, J=6.16 and 13.19 Hz, 1H), 1.74 (d, J=12.32 Hz, 1H), 1.41 (s. 3H), 1.28 (s, 3H). 13C NMR (DMSO-d) δ 158.19, 157.27, 140.80, 132.25, 132.15, 128.31, 126.98, 126.69, 126.18, 119.28, 118.13, 102.06., 77.37, 43.08, 42.01, 37.80, 29.15, 24.47. MS: (M+H)+ @336.

Provenance & Evidence