W.-M. Dai et al. / Tetrahedron 61 (2005) 6879–6885
6883
4
.2.3. 3,4-Dihydro-2,6-dimethyl-3-oxo-2H-1,4-benzoxa-
benzoxazine (3h). Prepared in 44% yield. Compound 3h.
A dark brown crystalline solid; mp 140.8–141.8 8C
zine (3c). Prepared in 63% yield. Compound 3c. A light
brown crystalline solid; mp 143.4–144.2 8C (EtOAc–
hexane); R Z0.38 (33% EtOAc in hexane); IR (film)
(EtOAc–hexane); R Z0.19 (33% EtOAc in hexane); IR
f
K1
1
(film) 1679, 1515, 1159 cm
acetone-d ) d 9.60 (br s, 1H), 7.05–7.01 (m, 1H), 6.71–
;
H NMR (300 MHz,
f
K1
1
1
683, 1608, 1496, 1399 cm
;
H NMR (300 MHz,
6
CD OD) d 7.00–6.88 (m, 3H), 4.72 (q, JZ6.8 Hz, 1H),
6.67 (m, 2H), 4.73 (q, JZ6.8 Hz, 1H), 3.89 (s, 3H), 1.61 (d,
3
1
3
13
2
CD OD) d 170.4, 142.7, 133.7, 128.4, 125.5, 117.8, 117.5,
.43 (s, 3H), 1.65 (d, JZ6.8 Hz, 3H); C NMR (300 MHz,
JZ6.8 Hz, 3H); C NMR (75 MHz, acetone-d ) d 167.5,
6
157.4, 143.4, 122.3, 117.1, 109.0, 104.0, 74.5, 56.2, 16.9;
MS (CCI) m/z 194 (MCH , 100); Anal. Calcd for
3
C
4.5, 21.8, 16.8; MS (CESI) m/z 178 (MCH , 100); Anal.
C
7
Calcd for C H NO : C, 67.78; H, 6.26; N, 7.90. Found: C,
C H NO : C, 62.17; H, 5.74; N, 7.25. Found: C, 62.19;
10 11 3
1
0
11
2
6
7.84; H, 6.36; N, 7.93%.
H, 5.71; N, 7.30%.
4.2.4. 3,4-Dihydro-2,7-dimethyl-3-oxo-2H-1,4-benzoxa-
zine (3d). Prepared in 64% yield. Compound 3d. A grey
4.2.9. 3,4-Dihydro-6-ethylsulfonyl-2-methyl-3-oxo-2H-
1,4-benzoxazine (3i). Prepared in 57% yield. Compound
3i. A white crystalline solid; mp 156.6–157.4 8C (EtOAc–
crystalline solid; mp 173.4–174.2 8C (EtOAc–hexane); R Z
f
0
1
1
3
.36 (33% EtOAc in hexane); IR (film) 2917, 1683,
520 cm ; H NMR (300 MHz, acetone-d ) d 9.56 (br s,
hexane); R Z0.33 (33% EtOAc in hexane); IR (film) 3508,
f
K1
1
K1
1
3420, 1682, 1607, 1496, 1294, 1133 cm
;
H NMR
6
H), 6.85–6.74 (m, 3H), 4.56 (q, JZ6.6 Hz, 1H), 2.24 (s,
(300 MHz, CD OD) d 7.69 (dd, JZ8.4, 1.6 Hz, 1H), 7.59
3
1
3
H), 1.45 (d, JZ6.6 Hz, 3H); C NMR (75 MHz, DMSO-
(d, JZ1.6 Hz, 1H), 7.35 (d, JZ8.4 Hz, 1H), 4.97 (q, JZ
d ) d 166.8, 142.7, 132.4, 125.1 122.8, 116.9, 115.3, 72.6,
6.9 Hz, 1H), 3.37 (q, JZ7.4 Hz, 2H), 1.74 (d, JZ6.8 Hz,
6
C
0.4, 16.1; MS (CESI) m/z 178 (MCH , 100); Anal. Calcd
13
2
for C H NO : C, 67.78; H, 6.26; N, 7.90. Found: C, 67.70;
H, 6.21; N, 8.28%.
3H), 1.41 (t, JZ7.3 Hz, 3H); C NMR (75 MHz, CD OD)
3
d 169.1, 149.3, 133.9, 129.6, 125.6, 118.8, 116.9, 75.2, 51.7,
17.1, 8.0; MS (CESI) m/z 256 (MCH , 100); Anal. Calcd
1
0
11
2
C
for C H NO S: C, 51.75; H, 5.13; N, 5.49. Found: C,
1
1
13
4
4
.2.5. 3,4-Dihydro-2,6,8-trimethyl-3-oxo-2H-1,4-benz-
51.98; H, 5.13; N, 5.71%.
oxazine (3e). Prepared in 61% yield. Compound 3e. A
light brown crystalline solid; mp 180.0–180.4 8C (EtOAc–
4.2.10. 6-Chloro-3,4-dihydro-2-methyl-3-oxo-2H-1,4-
benzoxazine (3j). Prepared in 80% yield. Compound 3j.
A white crystalline solid; mp 171.6–172.2 8C (EtOAc–
hexane); R Z0.38 (33% EtOAc in hexane); IR (film) 1687,
f
K1
1
612 cm ; H NMR (300 MHz, CD OD) d 6.82 (s, 1H),
1
6
3
3
.72 (s, 1H), 4.73 (q, JZ6.8 Hz, 1H), 2.39 (s, 3H), 2.34 (s,
H), 1.65 (d, JZ6.8 Hz, 3H); C NMR (75 MHz, CD OD)
hexane); R Z0.49 (33% EtOAc in hexane); IR (film) 1694,
f
1
3
K1 1
1608, 1497 cm ; H NMR (300 MHz, CD OD) d 7.13–
3
3
d 170.5, 140.7, 133.0, 128.0, 127.5, 127.3, 115.2, 74.6, 21.1,
7.07 (m, 3H), 4.80 (q, JZ6.8 Hz, 1H), 1.68 (d, JZ6.8 Hz,
C
6.8, 15.7; MS (CESI) m/z 192 (MCH , 100); Anal. Calcd
13
3H); C NMR (75 MHz, CD OD) d 169.8, 143.7, 130.1,
1
for C H NO : C, 69.09; H, 6.85; N, 7.32. Found: C, 69.08;
H, 6.80; N, 7.46%.
3
128.6, 124.6, 119.3, 116.8, 74.8, 16.8; MS (CESI) m/z 198
(MCH , 100), 200 (MC2CH , 20); Anal. Calcd for
1
1
13
2
C
C
C H ClNO : C, 54.70; H, 4.08; N, 7.09. Found: C, 54.66; H,
9
8
2
4
.2.6. 6-tert-Butyl-3,4-dihydro-2-methyl-3-oxo-2H-1,4-
4.13; N, 7.27%.
benzoxazine (3f). Prepared in 76% yield. Compound 3f.
A white crystalline solid; mp 156.6–157.4 8C (EtOAc–
4.2.11. 6-Chloro-3,4-dihydro-2-methyl-7-nitro-3-oxo-
2H-1,4-benzoxazine (3k). Prepared in 72% yield.
Compound 3k. A pale brown crystalline solid; mp 213.6–
hexane); R Z0.30 (33% EtOAc in hexane); IR (film) 1713,
f
K1
563, 1458 cm ; H NMR (300 MHz, acetone-d ) d 9.61
1
1
6
(
1
br s, 1H), 7.18 (d, JZ2.1 Hz, 1H), 7.13 (dd, JZ8.4, 2.1 Hz,
H), 7.01 (d, JZ8.4 Hz, 1H), 4.73 (q, JZ6.8 Hz, 1H), 1.62
d, JZ6.7 Hz, 3H), 1.42 (s, 9H); C NMR (75 MHz,
214.0 8C (EtOAc–hexane); R Z0.28 (33% EtOAc in
f
K1
1
hexane); IR (film) 1708, 1535, 1305 cm
(300 MHz, CD OD) d 7.84 (s, 1H), 7.26 (s, 1H), 4.94 (q,
;
H NMR
1
3
(
acetone-d ) d 168.3, 146.6, 142.4, 128.5, 121.2, 117.2,
3
1
3
6
JZ6.8 Hz, 1H), 1.74 (d, JZ6.8 Hz, 3H); C NMR
1
H , 100); Anal. Calcd for C H NO : C, 71.21; H, 7.81; N,
13.8, 74.4, 35.2, 32.1 (!3), 16.9; MS (CCI) m/z 220 (MC
(75 MHz, DMSO-d ) d 166.5, 141.4, 141.0, 133.1, 119.7,
6
C
C
116.7, 114.3, 73.1, 16.1; MS (CCI) m/z 243 (MCH , 100),
1
3
17
2
C
245 (MC2CH , 42); Anal. Calcd for C H ClN O : C,
6
.39. Found: C, 71.17; H, 7.87; N, 6.38%.
9
7
2 4
44.55; H, 2.91; N, 11.55. Found: C, 44.70; H, 2.99; N,
11.64%.
4
.2.7. 3,4-Dihydro-2-methyl-6-phenyl-3-oxo-2H-1,4-
benzoxazine (3g). Prepared in 58% yield. Compound 3g.
A grey crystalline solid; mp 180.0–180.4 8C (EtOAc–
4.2.12. 3,4-Dihydro-2-methyl-5-nitro-3-oxo-2H-1,4-
benzoxazine (3l). Prepared in 60% yield. Compound 3l. A
light yellow crystalline solid; mp 141.6–142.4 8C (EtOAc–
hexane); R Z0.37 (33% EtOAc in hexane); IR (film)
f
K1
689, 1602, 1488 cm ; H NMR (300 MHz, acetone-d ) d
1
1
9
7
6
.87 (br s, 1H), 7.73 (d, JZ7.5 Hz, 2H), 7.37–7.60 (m, 5H),
.18 (d, JZ8.2 Hz, 1H), 4.82 (q, JZ6.8 Hz, 1H), 1.66 (d,
hexane); R Z0.47 (33% EtOAc in hexane); IR (film) 3297,
f
K1
1702, 1527, 1294 cm ; H NMR (300 MHz, acetone-d ) d
1
6
1
3
JZ6.8 Hz, 3H); C NMR (75 MHz, acetone-d ) d 168.2,
8.08 (d, JZ8.4 Hz, 1H), 7.56 (d, JZ7.9 Hz, 1H), 7.33 (dd,
JZ8.1, 8.1 Hz, 1H), 4.98 (q, JZ6.6 Hz, 1H), 1.75 (d, JZ
6 6
6
1
44.2, 141.5, 136.8, 130.1 (!2), 129.4, 128.3 (!2), 127.7,
22.9, 118.2, 115.2, 74.6, 17.0; MS (CCI) m/z 240 (MC
1
6.6 Hz, 3H); C NMR (75 MHz, DMSO-d Cacetone-d ) d
3
1
H , 100); Anal. Calcd for C H NO : C, 75.30; H, 5.48; N,
C
1
5
13
2
167.1, 145.5, 135.7, 124.6, 123.1, 123.0, 119.4, 73.1, 16.0;
MS (CESI) m/z 209 (MCH , 100); Anal. Calcd for
C
5
.85. Found: C, 75.29; H, 5.44; N, 6.18%.
C H N O : C, 51.93; H, 3.87; N, 13.46. Found: C, 51.90; H,
9
8 2 4
4
.2.8. 3,4-Dihydro-6-methoxy-2-methyl-3-oxo-2H-1,4-
3.81; N, 13.46%.