R. K. Tiwari et al. / Tetrahedron 61 (2005) 9513–9518
9517
(3H, s, CH3); dC (100 MHz, CDCl3) 139.0, 137.0, 135.7,
131.7, 129.0, 128.1, 124.3, 120.6, 119.5, 118.1, 108.3,
105.8, 56.2, 42.5, 39.8, 21.0, 8.4; LCMS m/z 275 (100%,
MK1), 276 (20%, M), 277 (8%, MC1).
Ph), 5.32 (1H, s, H-1), 4.10–3.91 (2H, m, H-4), 3.27–3.15
(2H, m, H-3), 1.82 (4H, s, NH, CH3); dC (100 MHz, CDCl3)
164.2, 139.8, 139.5, 139.1, 132.8, 129.9, 120.9, 119.3,
118.2, 108.2, 102.4, 100.5, 55.8, 42.7, 39.9, 8.5; LCMS m/z
281.16 (76%, MC1), 282.18 (14%, MC2), 279.14 (100%,
MK2).
4.1.3. (4-Methoxyphenyl)-10-methyl-1,2,3,4-tetrahydro-
pyrazino[1,2-a]indole 7c. (White needles from EtOAc/
hexanes). Mp 126–128 8C; [Found: C, 77.72; H, 9.51; N,
9.54 C19H20N2O requires C, 78.00; H, 9.58; N, 9.58%]; nmax
(KBr) 3320, 3049, 3044, 2955, 2920, 2877, 1041, 742,
677 cmK1; dH (300 MHz, CDCl3) 7.52–6.84 (8H, m, Ph,
Ph), 5.33 (1H, s, H-1), 4.16–3.99 (2H, m, H-4), 3.79 (3H, s,
OMe), 3.36–3.15 (2H, m, H-3), 1.86 (3H, s, CH3), 1.66 (1H,
s, NH); dC (100 MHz, CDCl3) 150.9, 145.7, 143.2, 131.5,
130.9, 127.0, 119.6, 119.1, 118.6, 116.1, 108.3, 105.8, 58.2,
56.2, 42.5, 39.8, 8.4; LCMS m/z 293 (5%, MC1); 292
(30%, M); 291 (100%, MK1).
4.1.8. 10-Methyl-1-pyridin-2-yl-1,2,3,4-tetrahydropyra-
zino[1,2-a]indole 7h. (White needles from EtOAc/
hexanes). Mp 127–128 8C; [Found: C, 77.18; H, 6.34; N,
15.69 C17H17N3 requires C, 77.54; H, 6.51; N, 15.96%];
nmax (KBr) 3306, 3051, 3044, 2958, 2924, 2881, 1580, 1440,
748, 704 cmK1; dH (300 MHz, CDCl3) 7.82–6.83 (8H, m,
Ph, pyri), 5.19 (1H, s, H-1), 3.97–3.76 (2H, m, H-4), 3.15–
3.03 (2H, m, H-3), 1.95 (3H, s, CH3), 1.80 (1H, s, NH); dC
(100 MHz, CDCl3) 154.2, 148.4, 138.8, 137.5, 134.9, 130.8,
122.0, 120.7, 119.6, 119.1, 118.6, 111.1, 108.0, 54.2, 43.6,
41.5, 8.6; LCMS m/z 364 (40%, MC1).
4.1.4. 1-(4-Nitrophenyl)-10-methyl-1,2,3,4-tetrahydro-
pyrazino[1,2-a]indole 7d. (Yellow crystals from EtOAc/
hexanes). Mp 112–114 8C; [Found: C, 70.31; H, 5.56; N,
13.45 C18H17N3O2 requires C, 70.34; H, 5.58; N, 13.67%];
nmax (KBr) 3321, 3050, 3042, 2955, 2922, 2876, 1520, 1360,
750, 680 cmK1; dH (300 MHz, CDCl3) 7.53–6.90 (8H, m,
Ph, Ph); 5.31 (1H, s, H-1), 4.15–3.96 (2H, m, H-4), 3.30–
3.15 (2H, m, H-3), 2.70 (3H, s, CH3), 1.60 (1H, s, NH); dC
(100 MHz, CDCl3) 135.9, 132.4, 130.0, 129.3, 127.3, 125.7,
121.4, 119.5, 118.5, 117.0, 111.1, 109.0, 56.2, 42.7, 40.9,
8.4; LCMS m/z 307 (80%, M), 308 (20%, MC1), 185.2
(14%, MK122).
4.1.9. 10-Methyl-1-thien-2-yl-1,2,3,4-tetrahydropyra-
zino[1,2-a]indole 7i. (Brown needles from EtOAc/hex-
anes). Mp 130–131 8C; [Found: C, 71.54; H, 5.98; N, 10.38;
S, 11.87 C16H16N2S requires C, 71.60; H, 6.01; N, 10.44; S,
11.95%]; nmax (KBr) 3320, 3059, 3043, 2966, 2922, 2888,
775, 650, 698 cmK1; dH (300 MHz, CDCl3) 7.43–6.33 (7H,
m, Ph, thien), 5.19 (1H, s, H-1), 3.87 (2H, m, H-4), 2.90 (2H,
m, H-3), 2.20 (3H, s, CH3), 1.90 (1H, s, NH); dC (100 MHz,
CDCl3) 139.5, 139.1, 138.1, 132.0, 127.5, 124.5, 121.0,
120.4, 119.5, 117.6, 108.1, 106.0, 54.2, 43.2, 40.5, 8.4;
LCMS m/z 269 (25%, MC1).
4.1.5. 1-(4-Chlorophenyl)-10-methyl-1,2,3,4-tetrahydro-
pyrazino[1,2-a]indole 7e. (White needles from EtOAc/
hexanes). Mp 110–111 8C; [Found: C, 72.52; H, 5.40; N,
9.21 C18H17N2Cl requires C, 72.80; H, 5.70; N, 9.40%];
nmax (KBr) 3310, 3050, 3043, 2956, 2922, 2878, 1087, 760,
689 cmK1; dH (300 MHz, CDCl3) 7.54–7.11 (8H, m, Ph, Ph)
5.34 (1H, s, H-1), 4.15–3.96 (2H, m, H-4), 3.30–3.15 (2H,
m, H-3), 1.88 (s, 4H, NH, CH3); dC (100 MHz, CDCl3)
158.7, 140.6, 136.3, 133.5, 131.1, 129.7, 128.6, 125.1,
121.0, 119.4, 118.3, 108.5, 55.7, 42.6, 39.8, 8.5; LCMS m/z
297.1 (50%, MC1), 295 (100%, MK1), 280.1 (7%, MK
15), 186.2 (12%, MK110).
Acknowledgements
We gratefully acknowledge financial support from Depart-
ment of Science and Technology, New Delhi, for this work.
We are thankful to Prof. V. K. Singh for valuable
suggestions and discussion. R. K. T. thank J. A. Ganguly
for JRF and J. S. are thankful to CSIR for JRF.
References and notes
4.1.6. 1-(4-Bromophenyl)-10-methyl-1,2,3,4-tetrahydro-
pyrazino[1,2-a]indole 7f. (White needles from EtOAc/
hexanes). Mp 115–117 8C; [Found: C, 63.03; H, 5.25; N,
8.27 C18H17N2Br requires C, 63.30; H, 5.03; N, 8.21%];
nmax (KBr) 3311, 3050, 3043, 2957, 2922, 2879, 760,
684 cmK1; dH (300 MHz, CDCl3) 7.54–7.11 (8H, m, Ph,
Ph), 5.32 (1H, s, H-1), 4.10–3.90 (2H, m, H-4), 3.20–3.15
(2H, m, H-3), 1.80 (3H, s, CH3), 1.26 (1H, s, NH); dC
(100 MHz, CDCl3) 141.0, 135.5, 133.1, 132.1, 131.6, 130.9,
130.0, 121.0, 119.3, 118.2, 108.5, 106.1, 55.7, 42.6, 39.7,
8.4; LCMS m/z 343.1 (45%, MC2), 341 (100%, M), 339
(65%, MK2).
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