1046
B. Kersting and M. DeLion • Benzisochalcogenol and -azole Derivatives
equimolar mixture of 3a and 8a (vide infra) as evidenced
placed in a dry-ice/2-propanol bath. To this suspension
was added via syringe n-BuLi (26.4 ml of a 2.5 M solution
in hexanes, 66.0 mmol) to obtain a bright-red solution.
The reaction mixture was allowed to warm to r. t., and the
resulting yellow suspension was stirred fur further 12 h.
Selenium (1.58 g, 20.0 mmol) was then added in small
portions at -76 °C. After being stirred for 2 further days
under N2, the flask was exposed to air for 5 d. The reaction
mixture was then acidified and the product extracted with
CH2C12. The organic phase was separated, dried with
M gS04, and the solvent removed in vacuum to give a
brown oil which was purified by column chromatography
(S i02, eluent 10%MeOH/CH2Cl2, Rf = 0.54). Yield: 3.0 g
(46%). IR (KBr, cm“ 1): 3264, 3076 i/(NH), 1607, 1547
u(CO). ' H N M R (CDCI3): 6 = 8.14 (d, 2J = 1.1 Hz, 1H,
Ar//), 7.98 (d, 2J = 7.7 Hz, 1H, Ar//), 7.46 (t, 2J = 7.7 Hz,
1H, Ar//), 7.11 (d, 2J = 7 Hz, 1H, N//CH), 4.78 (spt, V =
6.9 Hz, 1H, NCH), 4.34 (d spt, V = 7.0 Hz, 1H, NHC//),
1.41 (d, V = 7.0 Hz, 6H, C //3), 1.26 (d, 3J = 7.0 Hz, 6H,
C //3). 13C{'H} NMR (CDCI3): 6 = 165.7, 165.6, 141.1,
131.0, 130.6, 127.2, 126.1, 125.9, 46.1,42.8, 23.3,22.5.
by thin layer chromatography (3a: Rf = 0.35, 8a: Rf
0.54). Addition of iodine to the mixture resulted in com-
plete oxidation of 3a to give 8a as the sole product. The
product was precipitated by addition of H20 , filtered, and
dried in air. Yield: 251 mg (95%). The analytical data for
this material are identical to those of 8a (see below).
=
2-Isopropyl-7-(N-isopropyl-carbamoyl)benzisothiazole-
3-one (8a)
To a solution of 3a (280 mg, 1.00 mmol) in methanol
(10 ml) was added a solution of I2 (254 mg, 1.00 mmol) in
methanol (1 ml), followed by a solution of triethylamine
(202 mg, 2.00 mmol) in methanol (2 ml). The reaction
mixture was stirred for 30 min, water (10 ml) was added,
and the solution was acidified to pH = 1 by addition of
6M HC1. The resulting white precipitate was collected by
filtration. An analytical sample was obtained by column
chromatography (R, = 0.54, 10%MeOH/CH2Cl2). Yield:
0.26 g (93%). M. p. 198 - 200 °C. IR (KBr, cm ~1): 3276,
3079 i/(NH), 1619, 1547 v{CO). 'H NMR (CDCI3): 6 =
8.13 (d, 2J = 7.7 Hz, 1H, Ar//), 7.98 (d, 2J = 7.7 Hz, 1H,
Ar//), 7.40 (t, 2J = 7.7 Hz, 1H, Ar//), 7.02 (d, 2J = 1 Hz,
1H, NZ/CH), 4.91 (spt, V = 6.9 Hz, 1H, NC//), 4.35 (d
spt, V = 6.9 Hz, 1H, NHC//), 1.46 (d, 37 = 6.6 Hz, 6H,
C //3), 1.31 (d, V = 6.6 Hz, 6H, C //3). 13C{'H} NMR
(CDCI3): 6 = 164.9, 164.0, 141.8, 129.2, 127.7, 127.2,
125.0, 124.4, 45.8,42.5, 22.6, 22.2.
C |4H |8N20 2Se (325.27)
Calcd C 51.70 H 5.58 N8.61%,
Found C 51.48 H 5.32 N 8.43%.
2-Isopropyl- 7-(N-isopropyl-carbamoyl)benzisotellur-
azole-3-one (10a)
This compound was prepared as described above for 9a
from la and tellurium (2.00 g, 20.0 mmol). Yield: 1.96 g
(26%). IR (KBr, cm-1): 3236, 3064 i/(NH), 1595, 1554
//(CO). 'H NMR (CDCI3): 6 = 8.86 (d, 3J = 7.0 Hz, 1H,
NH), 8.50 (d, 2J = 7.7 Hz, 1H, Ar//), 8.14 (d, 2J = 7.7 Hz,
1H, Ar//), 7.39 (d, 2J = 1 Hz, 1H, NZ/CH), 4.44 (spt, V =
6.9 Hz, 1H, NC//), 4.38 (d spt, V = 7.0 Hz, 1H, NHC//),
1.31 (d, V = 7.0 Hz, 6H, C //3), 1.30 (d, 37 = 7.0 Hz, 6H,
C //3). ,3C{'H} NMR (CDCI3): 6 = 168.0, 166.9, 135.9,
132.8, 131.7 (CH), 129.0, 128.1 (CH), 127.4 (CH), 46.0,
43.3, 24.6, 22.5.
C,4Hi8N20 2S (278.37)
Calcd C 60.41 H 6.52 N 10.06%,
Found C 60.30 H6.31
N 9.83%.
2-tert-Butyl-7-(N-tert-butyl-carbamoyl)-benzisothiazole-
3-one (8b)
This compound was prepared from 3b (308 mg,
1.00 mmol) by the procedure detailed above for 8a. Yield:
278 mg (90%). IR (KBr, cm-1): 3275 i/(NH), 1622, 1542
v(CO). 1H NMR (CDCI3): 6 = 8.10 (d, 2J = 7.5 Hz, 1H,
Ar//), 7.69 (d, 2J = 7.5 Hz, 1H, Ar//), 7.42 (t, 2J = 7.5 Hz,
1H, Ar//), 6.30 (s, 1H, N//CO), 1.73 (s, 9H, C //3), 1.51
(s, 9H, C //3). 13C{’H} NMR (CDCI3): <5= 165.2, 164.7,
140.6,129.2,128.8 (CH), 127.2 (CH), 125.1 (CH), 124.8,
58.1,52.3, 28.9, 28.4.
Ci4H l8N20 2Te (373.91)
Calcd C 44.97 H 4.85 N 7.49%,
Found C 45.13 H 4.83 N7.31%.
2-isopropyl-7-(N-isopropyl-carbamoyl)benzisothi-
azole-1,3-dione (11a)
Ci6H22N20 2S (306.42)
Calcd C 62.72 H 7.24 N9.14%,
Found C 62.34 H7.31 N9.13%.
To a solution of 8a (278 mg, 1.00 mmol) in acetic
acid (3 ml) was added 30% aqueous hydrogen peroxide
(1 ml). After stirring for 12 h at r. t., water (25 ml) was
added, and the product extracted three times with CH2C12
(35 ml). The combined organic phases were washed with
1 M NaHC03, dried over M gS04, filtered and evapo-
rated to dryness. The pale yellow solid was recrystal-
2-Isopropyl-7-(N-isopropyl-carbcimoyl)benzisoselen-
azole-3-one (9a)
A flask containing a mixture of la (4.97 g, 20.0 mmol),
TMEDA (7.67 g. 66.0 mmol), and 50 ml of THF was
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