One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives
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2-Amino-3-cyano-4-(3-chlorophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydro-
benzo[b]pyran (4f). The general procedure was used to give 4f (95%) as a white solid,
mp 224–226◦C, lit.21 224–225◦C. 1H NMR: δ 0.96 (s, 3H), 1.04 (s, 3H), 2.12 (d, 1H), 2.26
(d, 1H), 2.50 (s, 2H), 4.21 (s, 1H), 7.12 (s, 2H), 7.16–7.34 (m, 4H). IR (KBr) νmax: 3325,
2958, 2167, 1656, 1379, 1220 cm−1. EI-MS (m/z): 328 (M+).
2-Amino-3-cyano - 4 - (4-methoxyphenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahy-
drobenzo[b]pyran (4g). The general procedure was used to give 4g (90%) as a white solid,
mp 197–199◦C, lit.21 199–201◦C. 1H NMR: δ 0.95 (s, 3H), 1.03 (s, 3H), 2.08 (d, 1H), 2.22
(d, 1H), 2.25 (s, 3H), 2.49 (s, 2H), 3.34 (s, 3H), 4.11 (s, 1H), 6.85 (s, 2H), 6.82–7.06 (m,
4H). IR (KBr) νmax: 3356, 2969, 2157, 1658, 1382, 1217 cm−1. EI-MS (m/z): 324 (M+).
2-Amino-3-cyano-4-(2,5-dimethoxyphenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetra-
hydrobenzo[b]pyran (4h). The general procedure was used to give 4h (94%) as a white
1
solid, mp 178–180◦C. H NMR: δ 0.97 (s, 3H), 1.04 (s, 3H), 2.23 (d, 1H), 2.25 (d, 1H),
2.48 (s, 2H), 3.68 (d, 6H), 4.44 (s, 1H), 6.51 (s, 2H), 6.70–6.87 (m, 4H). IR (KBr) νmax:
3375, 2962, 2179, 1642, 1358, 1225 cm−1. EI-MS (m/z): 354 (M+).
Anal. Calcd for C20H22N2O4: C, 67.78; H, 6.26; N, 7.90. Found: C, 67.89; H, 6.02; N,
7.83.
2-Amino - 3 - cyano-4-(2-methoxyphenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahy-
drobenzo[b]pyran (4i). The general procedure was used to give 4i (92%) as a white solid,
mp 204–205◦C. 1H NMR: δ 0.96 (s, 3H), 1.04 (s, 3H), 2.05 (d, 1H), 2.25 (d, 1H), 2.49 (s,
2H), 3.75 (s, 3H), 4.47 (s, 1H), 6.82 (s, 2H), 6.87–7.18 (m, 4H). IR (KBr) νmax: 3396,
2964, 2188, 1655, 1371, 1251 cm−1. EI-MS (m/z): 324 (M+).
Anal. Calcd for C19H20N2O3: C, 70.35; H, 6.21; N, 8.64. Found: C, 70.29; H, 6.02; N,
8.89.
2-Amino-3-cyano-4-(furan-2-yl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo-
[b]pyran (4j). The general procedure was used to give 4j (76%) as a white solid, mp
1
217–219◦C. H NMR: δ 0.99 (s, 3H), 1.05 (s, 3H), 2.17 (m, 2H), 2.48 (m, 2H), 4.33 (s,
1H), 6.05 (s, 1H), 6.32 (s, 1H),7.07 (s, 2H), 7.48 (s, 1H),. IR (KBr) νmax: 3355, 2941,
2202, 1680, 1363, 1223 cm−1. EI-MS (m/z): 284 (M+).
Anal. Calcd for C16H16N2O3: C, 67.59; H, 5.67; N, 9.85. Found: C, 67.88; H, 5.56; N,
9.63.
2-Amino - 3 - cyano - 4 - ethyl -7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]-
pyran (4k). The general procedure was used to give 4k (70%) as a white solid, mp
1
180–182◦C. H NMR: δ 0.79 (t, 3H), 1.10 (d, 6H), 1.45 (m, 1H), 1.60 (m, 1H), 2.30 (m,
2H), 2.45 (m, 2H), 3.24 (s, 1H), 6.96 (s, 2H), IR (KBr) νmax: 3368, 2961, 2188, 1682,
1382, 1216 cm−1. EI-MS (m/z): 246 (M+).
Anal. Calcd for C14H18N2O2: C, 68.27; H, 7.37; N, 11.37. Found: C, 68.54; H, 7.27;
N, 11.18.
References
1. D. C. Rideout and R. Breslow, J. Am. Chem. Soc., 102, 7817 (1980).
2. R. Breslow, U. Maitra, and D. Rideout, Tetrahedron Lett., 24, 1901 (1983).
3. T. A. Eggelte, H. De Koning and H. O. Huisman, Tetrahedron, 29, 2491 (1973).