SUBSTITUTED TETRAHYDROCHROMENES
2825
1
=
(C C stretching of phenyl), 1350 (C-N stretching), 1275, 1190 (C-O stretching); H
NMR: d (in ppm): 7.13 (d, J ¼ 8.0 Hz, ArH, 2H), 6.99 (d, J ¼ 8.0 Hz, ArH, 2H), 6.21
(s, NH2, 2H), 4.66 (s, C4-H, 1H), 4.05 (q, J ¼ 7.10 Hz, -CH2CH3, 2H), 2.40 (s, meth-
ylene protons at C-6, 2H), 2.25 (s, NCH3, 6H), 2.23 (d, J ¼ 13.60 Hz, C8-H, 1Hax),
2.17 (d, J ¼ 13.60 Hz, C8-H, 1Heq), 1.16 (t, J ¼ 7.10 Hz, -CH2CH3, 3H), 1.07 (s, CH3
13
=
at C-7, 3H), 0.96 (s, another CH3 at C-7, 3H); C NMR d (in ppm): 196.3 (C O),
169.6 (C-2), 161.2 (COOCH2CH3), 158.3 (C-9), 142.8, 135.3, 128.5 (2C), 128.0 (2C)
(6C-aromatic), 117.0 (C-10), 80.7 (C-3), 59.5 (COOCH2CH3), 50.8 (C-6), 40.6 (C-8),
33.3 (C-4), 32.1 (C-7), 29.0 (CH3 at C-7), 27.3 (another CH3 at C-7), 20.9–20.6
[N(CH3)2], 14.1 (COOCH2CH3). MS: m=z 384.08 (Mþ). Anal. calcd. for
C22H28N2O4: C, 68.75; H, 7.29; N, 3.64. Found: C, 63.95; H, 5.88; N, 3.66.
2-Amino-4-(2-methoxyphenyl)-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydro-4H-chromene-3-carboxylic Acid Ethyl Ester, 4c
Yield 70%; white crystalline solid; mp 153–154 ꢁC; Rf value in TLC 0.69 (neat
chloroform); IR (KBr) (nmax, cmꢂ1): 3450, 3400 (N-H), 1690, 1640 (C O), 1590,
=
=
1505 (C C stretching of phenyl), 1360 (C-N stretching), 1270, 1190 (C-O stretching);
1H NMR d (in ppm): 7.35 (d, J ¼ 7.70 Hz, ArH, 1H), 7.15–7.05 (m, ArH, 1H),
6.88–6.80 (m, ArH, 1H), 6.75 (d, J ¼ 8.40 Hz, ArH, 1H), 6.15 (br s, NH2, 2H),
4.80 (s, C4-H, 1H), 4.0 (q, J ¼ 7.80 Hz, -CH2CH3, 2H), 3.75 (s, OCH3, 3H), 2.45
(d, J ¼ 14.20 Hz, C6-H, 1Hax), 2.35 (d, J ¼ 14.20 Hz, C6-H, 1Heq), 2.20 (d,
J ¼ 15.40 Hz, C8-H, 1Hax), 2.15 (d, J ¼ 15.40 Hz, C8-H, 1Heq), 1.20 (t, J ¼ 7.80 Hz,
Hz, -CH2CH3, 3H), 1.10 (s, CH3 at C-7, 3H), 0.95 (s, another CH3 at C-7, 3H); MS:
m=z 371.20 (Mþ). Anal. calcd. for C21H25NO5: C, 67.92; H, 6.79; N, 3.77. Found: C,
67.73; H, 6.74; N, 3.75.
2-Amino-4-(2-chlorophenyl)-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydro-4H-chromene-3-carboxylic Acid Ethyl Ester, 4d
Yield 60%; white solid powder; mp 162–164 ꢁC; Rf value in TLC 0.70 (neat
chloroform); IR (KBr) (nmax, cmꢂ1): 3400, 3300 (N-H), 1680, 1640 (C O), 1630,
=
=
1520 (C C stretching of phenyl) 1360 (C-N stretching), 1270, 1190 (C-O stretching);
1H NMR d (in ppm): 7.35 (d, J ¼ 7.70 Hz, ArH, 1H), 7.20 (d, J ¼ 8.20 Hz, ArH, 1H),
7.18–7.10 (m, ArH, 1H), 7.10–7.02 (m, ArH, 1H), 6.25 (br s, NH2, 2H), 5.00 (s, C4-
H, 1H), 4.05 (q, J ¼ 7.40 Hz, -CH2CH3, 2H), 2.45 (s, methylene protons at C-6, 2H),
2.25 (d, J ¼ 13.80 Hz, C8-H, 1Hax), 2.15 (d, J ¼ 13.80 Hz, C8-H, 1Heq), 1.15 (t,
J ¼ 7.40 Hz, -CH2CH3, 3H), 1.10 (s, CH3 at C-7, 3H), 0.950 (s, another CH3 at
C-7, 3H); MS: m=z 375.15 (Mþ). Anal. calcd. for C20H22NO4Cl: C, 64.0; H, 5.87;
N, 3.73. Found: C, 63.84; H, 5.92; N, 3.84.
2-Amino-4-(4-methylphenyl)-5-oxo-5,6,7,8-tetrahydro-4H-
chromene-3-carboxylic Acid Ethyl Ester, 4e
Yield 55%; white crystalline solid; mp 168–169 ꢁC; Rf value in TLC 0.75 (neat
chloroform); IR (KBr) (nmax, cmꢂ1): 3400, 3000 (N-H), 1680, 1640 (C O), 1520
=
=
(C C stretching of phenyl), 1360 (C-N stretching), 1280, 1210 (C-O stretching);