Molecules 2009, 14
388
NMR (CDCl3) δ 3.07 (t, J = 7.9 Hz, 2H, CH2CH2Ph), 3.28 (s, 3H, NCH3), 3.90 (s, 3H, CO2CH3),
4.05–4.14 (m, 2H, CH2CH2Ph), 7.06 (ddd, J = 8.2, 6.9, 1.3 Hz, 1H, 5-H), 7.19–7.23 (m, 1H, 4’-H),
7.27–7.31 (m, 4H, 2’/3’/5’/6’-H), 7.51 (ddd, J = 8.6, 7.2, 1.6 Hz, 1H, 4-H), 7.96 (dd, J = 7.9, 1.6 Hz,
13
1H, 6-H), 8.80 (d, J = 8.6 Hz, 1H, 3-H), 10.84 (s, 1H, NH); C-NMR (CDCl3) δ 33.38 (CH2CH2Ph),
39.22 (NCH3), 52.35 (CO2CH3), 55.82 (CH2CH2Ph), 116.80 (C-1) 122.41 (C-5), 123.27 (C-3), 126.52
(C-4’), 128.60 (C-2’/6’), 128.91 (C-3’/5’), 130.27 (C-6), 132.99 (C-4), 138.55 (C-1’), 143.05 (C-2),
169.02 (CO2CH3), 179.87 (NHCS); Anal. calcd. for C18H20N2O2S: C, 65.8; H, 6.1; N, 8.5. Found: C,
64.9; H, 5.8; N, 8.9.
2-(Diethylamino)-4H-3,1-benzothiazin-4-one (2a)
Method 1: Methyl 2-(3,3-diethylthioureido)benzoate (1a, 0.799 g, 3.0 mmol) was kept in
concd. H2SO4 (12 mL) at r.t. for 24 h. The solution was poored into a mixture of ice–water (100 mL)
and EtOAc (100 mL). After neutralization, the aqueous layer was further extracted with EtOAc (2 ×
100 mL). The combined organic layers were dried over Na2SO4, filtered, and evaporated to dryness.
Recrystallisation from MeOH yielded 2a (0.505 g, 72%) as colourless needles, mp 74–75 °C (MeOH),
1
lit. [43] 72–74 °C; H-NMR (CDCl3) δ 1.24 (t, J = 7.3 Hz, 6H, CH2CH3), 3.59 (q, J = 7.3 Hz, 4H,
CH2CH3), 7.10 (ddd, J = 8.2, 7.6, 1.3 Hz, 1H, 6-H), 7.37 (dd, J = 7.9, 1.3 Hz, 1H, 8-H), 7.55 (ddd,
J = 8.5, 6.9, 1.6 Hz, 1H, 7-H), 8.00 (dd, J = 8.0, 1.6 Hz, 1H, 5-H); 13C-NMR (CDCl3) δ 13.03
(CH2CH3), 43.35 (CH2CH3), 116.29 (C-4a), 122.93 (C-6), 124.71 (C-5), 128.21 (C-8), 135.61 (C-7),
151.50 (C-8a), 155.43 (C-2), 184.52 (C-4); Anal. calcd. for C12H14N2OS: C, 61.5; H, 6.0; N, 12.0.
Found: C, 61.5; H, 6.0; N, 12.0.
Method 2: 2-(3,3-Diethylthioureido)-N,N-diethylbenzamide 6a (0.615 g, 2.0 mmol) was treated
with concd. H2SO4 (8 mL) as described under Method 1 obtaining 2a (0.449 g, 96%) as a white solid.
2-(N-Cyclohexyl-N-methylamino)-4H-3,1-benzothiazin-4-one (2b)
According to the preparation of 2a (Method 1), 2b (0.607 g, 74%) was obtained from 1b as
1
colourless plates, mp 111–114 °C (EtOH); H-NMR (CDCl3) δ 1.05–1.88 (m, 10H, 2’/3’/4’/5’/6’-H),
3.05 (s, 3H, NCH3), 4.22 (br s, 1H, 1’-H), 7.10 (ddd, J = 8.2, 6.9, 1.3 Hz, 1H, 6-H), 7.38 (dd, J = 8.2,
13
1.3 Hz, 1H, 8-H), 7.56 (ddd, J = 8.5, 6.9, 1.6 Hz, 1H, 7-H), 8.00 (dd, J = 8.2, 1.6 Hz, 1H, 5-H); C-
NMR (CDCl3) δ 25.40 (C-4’), 25.73 (C-3’/5’), 30.14 (C-2’/6’), 30.45 (NCH3), 56.82 (C-1’), 116.50
(C-4a), 123.01 (C-6), 124.75 (C-5), 128.18 (C-8), 135.64 (C-7), 151.36 (C-8a), 156.68 (C-2), 184.48
(C-4); Anal. calcd. for C15H18N2OS: C, 65.7; H, 6.6; N, 10.2. Found: C, 65.4; H, 6.6; N, 10.1.
2-(Pyrrolidin-1-yl)-4H-3,1-benzothiazin-4-one (2c)
Method 1: According to the preparation of 2a (Method 1), 2c (0.514 g, 74%) was obtained from 1c
as white needles, mp 105–107 °C (EtOH); 1H-NMR (CDCl3) δ 1.97–2.04 (m, 4H, 3’/4’-H), 3.58 (br s,
4H, 2’/5’-H), 7.10 (ddd, J = 8.2, 6.9, 1.3 Hz, 1H, 6-H), 7.39 (dd, J = 8.2, 1.0 Hz, 1H, 8-H), 7.56 (ddd,
J = 8.5, 7.3, 1.6 Hz, 1H, 7-H), 8.01 (dd, J = 8.4, 1.6 Hz, 1H, 5-H); 13C-NMR (CDCl3) δ 24.97 (C-
3’/4’), 47.67 (C-2’/5’), 116.58 (C-4a), 122.87 (C-6), 124.86 (C-5), 128.06 (C-8), 135.65 (C-7), 151.57