496
J. Zakrzewski – M. Krawczyk · Reactions of Nitroxides
◦
2
,2,6,6-Tetramethyl-1-oxyl-4-piperidyl chlorothionoformate
3g: M. p. 114 – 117 C. – MS (EI, 70 eV): m/z (%) = 259
+
(
2b) [15]
(14) [M] , 154 (100), 140 (9), 139 (7), 124 (78), 109 (96),
06 (27), 88 (22), 82 (11), 81 (13), 72 (34), 69 (17), 68 (8),
7 (20), 56 (16), 55 (21), 41 (29). – HRMS ((+)-EI): m/z =
59.1471 (calcd. 259.1480 for C H N O S, [M] ). – IR
1
6
2
Thiophosgene (1.55 mL, 2.33 g, 20.3 mmol) was added
with a syringe to benzene (16.5 mL). A solution of 2,2,6,6-
tetramethyl-4-hydroxypiperidin-1-oxyl (0.861 g, 5 mmol)
and pyridine (0.85 mL, 10.5 mmol) in benzene (8 mL) was
+
12
23 2 2
−1
(
KBr pellet): ν = 1534, 1282, 1196, 1144 cm
.
◦
added dropwise to the thiophosgene solution at 18 – 20 C.
2
,2,6,6-Tetramethyl-1-oxyl-4-piperidyl N,N-diethylcarbam-
ate (3c) and 2,2,6,6-tetramethyl-1-oxyl-4-piperidyl N,N-di-
ethylthionocarbamate (3h); general procedure
The reaction mixture was stirred for 20 min at ambient tem-
perature. The precipitate was filtered off and washed with
benzene (2 – 5 mL). Benzene was evaporated under reduced
pressure. The crystalline residue (1.284 g) was recrystal-
A chilled solution of diethylamine (∼ 30 mmol) in ben-
zene (∼ 5 mL) was added dropwise to a chilled solution
of chloroformate 2a or chlorothionoformate 2b (1 mmol) in
benzene (5 – 10 mL). The reaction mixture, protected from
humidity, was stirred for 1 h in an ice-water bath and for
lized from hexane (7 mL) to give 2b (0.7604 g, 61 %). M. p.
◦
78 – 84 C. – R : 0.24 (HA9), 0.55 (CA9), 0.61 (BA9), 0.77
f
+
(
1
BM9). – MS (EI, 70 eV): m/z (%) = 252 (3), 250 (10) [M] ,
55 (22), 154 (10), 140 (8), 139 (11), 124 (66), 109 (77), 100
2
4 h at r. t. The reaction mixture was filtered under reduced
(
(
(
1
19), 98 (18), 95 (8), 83 (28), 82 (33), 81 (25), 79 (18), 74
14), 69 (80), 67 (39), 60 (14), 56 (53), 55 (81), 53 (13), 44
26), 43 (19), 42 (100), 40 (24). – IR (KBr pellet): ν = 2976,
pressure, and the precipitate was washed with a small amount
of benzene. The filtrate was evaporated to dryness under re-
duced pressure. The residue was purified by column chro-
matography [HA9 (3c), BA95 (3h)] to give the expected
−1
308, 1270, 1243, 1017 cm [15].
2,2,6,6-Tetramethyl-1-oxyl-4-piperidyl N-alkylcarbamates
products 3c (59 %) or 3h (42 %) as red crystals.
and 2,2,6,6-tetramethyl-1-oxyl-4-piperidyl N-alkylthiono-
carbamates 3a, 3b, 3f, and 3g; general procedure
◦
3
c: M. p. 66 – 67 C. – MS (EI, 70 eV): m/z (%) = 271
8) [M] , 241 (3), 185 (3), 154 (38), 139 (17), 124 (98), 118
55), 109 (100), 100 (51), 83 (5), 82 (20), 81 (11), 69 (20),
8 (10), 67 (10), 55 (14), 41 (19). – HRMS ((+)-ESI): m/z =
94.1921 (calcd. 294.1919 for C H N O Na[M+Na] ). –
+
(
(
6
The solution of pre-cooled methylamine or dimethyl-
amine (∼ 40 – 60 mmol) in benzene (∼ 5 mL) was added
dropwise to a chilled solution of 2,2,6,6-tetramethyl-1-
oxyl-4-piperidyl chloroformate (2a) or 2,2,6,6-tetramethyl-
+
2
14 27
2
3
IR (KBr pellet): ν = 1693 (C=O), 1426, 1379, 1279, 1173,
−1
1
063 cm
3
.
1
-oxyl-4-piperidyl chlorothionoformate (2b) (1 mmol) in
benzene (5 – 10 mL). The reaction mixture, protected from
humidity, was stirred for 1 h in an ice-water bath and for 287 (13) [M] , 154 (87), 139 (15), 124 (62), 109 (100), 100
27). – HRMS ((+)-EI): m/z = 287.1785 (calcd. 287.1793 for
◦
h: M. p. 108 – 110 C. – MS (EI, 70 eV): m/z (%) =
+
(
24 h at r. t. After the reaction had been completed, the re-
+
C H N O S, [M] ). – IR (KBr pellet): ν = 1517, 1243,
action mixture was concentrated and filtered under reduced
pressure, and the precipitate was washed with a small amount 1172 cm
of benzene. The filtrate was concentrated under reduced pres-
14 27
2
2
−
1
.
2
,2,6,6-Tetramethyl-1-oxyl-4-piperidyl N,N-dialkylcarbam-
ates and 2,2,6,6-tetramethyl-1-oxyl-4-piperidyl N,N-dialkyl-
thionocarbamates 3d, 3e, 3i, and 3j; general procedure
sure. The residue (0.2 – 0.3 g) was purified by column chro-
matography using BM95 (3a, 3f) or BA95 (3b, 3g) as a
mobile phase to give the expected products 3a (85 %), 3b
(
94 %), 3f (35 %) or 3g (65 %) as red crystals.
A chilled solution of dipropylamine or dibutylamine
◦
3
a: M. p. 75 – 77 C. – MS (EI, 70 eV): m/z (%) = 229 (∼ 30 mmol) in benzene (∼ 5 mL) was added dropwise to a
+
(
(
[
13) [M] , 154 (18), 139 (12), 124 (86), 109 (100). – HRMS chilled solution of chloroformate 2a or chlorothionoformate
(+)-EI): m/z = 229.1547 (calcd. 229.1552 for C H N O , 2b (1 mmol) in benzene (5 – 10 mL). The reaction mixture,
11
21 2 3
+
M] ). – IR (KBr pellet): ν = 3319, 1710 (C=O), 1687, protected from humidity, was stirred for 1 h in an ice-water
−
1
1544, 1267, 1137 cm
.
bath and for 24 h at r. t. The reaction mixture was filtered un-
b: M. p. 106 – 108 C. – MS (EI, 70 eV): m/z (%) = 243 der reduced pressure, and the precipitate was washed with a
9) [M] , 213 (3), 154 (26), 139 (12), 124 (71), 109 (100), small amount of benzene. The filtrate was washed with 1 M
◦
3
+
(
9
0 (24), 82 (17), 81 (13), 72 (57). – HRMS ((+)-EI): m/z = hydrochloric acid (15 mL), concentrated sodium bicarbonate
+
243.1720 (calcd. 243.1709 for C H N O , [M] ). – IR solution (15 mL), and with water (15 mL). The solution was
12
23
2
1
3
−
(
KBr pellet): ν = 1703 (C=O), 1194 cm
.
dried over anhydrous magnesium sulfate. After filtration, the
f: M. p. 133 – 137 C. – MS (EI, 70 eV): m/z (%) = filtrate was evaporated to dryness under reduced pressure.
◦
3
+
245 (7) [M] , 154 (47), 140 (8), 139 (11), 124 (72), 109 The residue (0.3 – 0.45 g) was purified with column chro-
(
100). – HRMS ((+)-EI): m/z = 245.1319 (calcd. 245.1324 matography [HA9 (3d, 3e), BA95 (3e, 3i, 3j)] to give the ex-
+
for C H N O S, [M] ). – IR (film): ν = 3384, 1540, 1218, pected products 3d (72 %), 3e (60 %), 3i (41 %) as red crys-
1
1
1
21
2
2
−
1
127 cm
.
tals and 3j (53 %) as a red oil.
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