Cyclohexadienone Diazeniumdiolates
J . Org. Chem., Vol. 65, No. 18, 2000 5691
(C6CdO, vs)asym. UV-vis (H2O, λmax, nm (ꢀ, M-1 cm-1)): 250
9.24; N, 14.27. Found: C, 64.11; H, 9.23; N, 13.85. IR (KBr,
cm-1): 1666 (C6CdO, vs)sym, 1641 (C6CdO, vs)asym. UV-vis
(MeOH, λmax, nm (ꢀ, M-1 cm-1)): 240 (11,128). 1H NMR (CDCl3,
400 MHz) δ: 1.25 (s, 18 H), 1.77 (s, 3H), 2.89 (s, 6H), 6.84 (s,
2H); 13C NMR (CDCl3, 100 MHz) δ: 186.4, 147.9, 136.7, 46.9,
35.3, 29.5, 26.2.
1
(15 1 40). H NMR (CD3OD, 100 MHz) δ: 1.23 (s, 18 H), 1.67
(s, 3H), 7.01 (s, 2H). 13C NMR (CD3OD, 400 MHz) δ: 187.4,
146.6, 141.6, 68.6, 35.9, 29.9, 26.2.
Syn th esis of “O2-P r oton a ted ” (Z)-1-[4-(2,6-Di-ter t-bu -
tyl-4-m eth ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-d iolin -
ic Acid (1b). To a methanol solution of 1a (1.68 g, 0.0056 mol)
was added dropwise 0.1 M HCl solution with stirring until no
further precipitate of 1b formed. The precipitate was filtered,
washed with water, and dried. The crude product was dis-
solved in hexane (50 mL), and the solution was filtered to
remove any insoluble solid. On evaporation of the filtrate
colorless crystals were obtained. Yield: 1.25 g (80%). Anal.
Calcd for C15H24N2O3: C, 64.03; H, 8.96, N, 9.96. Found: C,
Syn t h esis of O2-Met h yl (Z)-1-[4-(2,6-Di-ter t-b u t yl-4-
m eth ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-d iola te (1c).
Meth od B. Silver (Z)-1-[4-(2,6-di-tert-butyl-4-methylcyclo-
hexadienonyl)]diazen-1-ium-1,2-diolate (1g) (1.36 g, 0.035
mol), freshly prepared from the reaction of aqueous solutions
of silver nitrate and 1a , and well-dried, was added in small
amounts to a solution of methyl iodide (3 mL, 0.048 mol) in
ether (50 mL) at 0-5 °C with stirring. The solution was stirred
for 2 h and filtered to remove silver iodide. The filtrate was
evaporated in the hood by bubbling nitrogen through the
headspace to yield O1-methyl (Z)-1-[4-(2,6-di-tert-butyl-4-me-
thylcyclohexadienonyl)]diazen-1-ium-1,2-diolate (1c) and O2-
methyl (Z)-1-[4-(2,6-di-tert-butyl-4-methylcyclohexadienonyl)]-
diazen-1-ium-1,2-diolate (1d ) isomeric mixture (15:1) as a
yellow solid. Yield: 0.81 g (79%). The isomers were separated
as described in method A.
63.80; H, 8.53; N, 9.87. IR (KBr, cm-1): 1668 (C6CdO, vs)sym
,
1648 (C6CdO,vs)asym. UV-vis (MeOH, λmax, nm (ꢀ, M-1 cm-1)):
1
234 (14 471). H NMR (CD3OD, 400 MHz) δ: 1.25 (s, 18H),
1.80 (s, 3H), 6.78 (s, 2H), 11.68 (s, 1H). 13C NMR (CD3OD, 100
MHz) δ: 185.1, 148.9, 135.3, 71.9, 35.4, 29.4, 26.1.
Syn t h esis of O2-Met h yl (Z)-1-[4-(2,6-Di-ter t-b u t yl-4-
m eth ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-d iola te (1c).
Meth od A. To a solution of 1b (0.43 g, 0.0015 mol) in ether
(25 mL) was slowly added an ethereal solution of diazomethane
that was prepared according to literature procedures,33 with
stirring at 0-5 °C. There was immediate effervescence. The
diazomethane addition was continued until the yellow color
of diazomethane persisted. The solution was then evaporated
with a stream of nitrogen gas in an efficient hood to yield a
∼5:1 mixture of O2-methyl (Z)-1-[4-(2,6-di-tert-butyl-4-meth-
ylcyclohexadienonyl)]diazen-1-ium-1,2-diolate (1c) and O1-
methyl (Z)-1-[4-(2,6-di-tert-butyl-4-methyl-cyclohexadienonyl)]-
diazen-1-ium-1,2-diolate (1d ) isomers as a yellow crystalline
product. Yield: 0.41 g, (91%). The two isomers were separated
by preparative silica gel chromatography or by preparative
silica gel TLC plates using CH2Cl2 as the eluent. The first
fraction contained the O1-methyl isomer (1c) (0.07 g) and the
second fraction contained the O2-methyl (Z)-1-[4-(2,6-di-tert-
butyl-4-methyl-cyclohexadienonyl)]diazen-1-ium-1,2-diolate (1d)
(0.34 g).
Syn th esis of Sod iu m (Z)-1-[4-(2,6-Di-ter t-bu tyl-4-m eth -
oxycycloh exadien on yl)]diazen -1-iu m -1,2-diolate (2a). This
compound was synthesized from the reaction of 2,6-di-tert-
butyl-4-methoxyphenol 2 (3.77 g, 0.016 mol) with nitric oxide
by the procedure described for the synthesis of 1a . Yield: 3.98
(78%). Anal. Calcd for C15H23N2O4Na: C, 56.60; H, 7.28; N,
8.80. Found: C, 56.20; H, 7.14; N, 8.77. IR (KBr, cm-1): 1670
(C6CdO, vs)sym, 1649 (C6CdO, s)asym. UV-vis (MeOH, λmax, nm
1
(ꢀ, M-1 cm-1)): 254 (13 042). H NMR (CD3OD, 400 MHz) δ:
1.22 (s, 18 H), 3.31 (s, 3H), 6.97 (s, 2H). 13C NMR (CD3OD,
100 MHz) δ: 187.4, 148.9, 135.5, 90.8 52.0, 36.2, 29.9.
Syn th esis of “O2-P r oton a ted ” (Z)-1-[4-(2,6-Di-ter t-bu -
t yl-4-et h ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-d iolin -
ic Acid (3b). The reaction of 2,6-di-tert-butyl-4-ethylphenol
(3) (5.15 g, 0.022 mol) with nitric oxide in the presence of
sodium methoxide carried out as described for 1a did not yield
any precipitate of sodium (Z)-1-[4-(2,6-di-tert-butyl-4-meth-
oxycyclohexadienonyl)]diazen-1-ium-1,2-diolate (3a ). The O2-
protonated product 3b was readily precipitated from the
resultant reddish solution on treatment with 0.1 M hydro-
chloric acid until no more precipitate was formed as described
in the synthesis of 1b. Yield: 5.70 g (88%). Anal. Calcd for
O2-Methyl (Z)-1-[4-(2,6-Di-tert-butyl-4-methyl-cyclohexadi-
enonyl)]diazen-1-ium-1,2-diolate (1c). Anal. Calcd for
C
16H26N2O3: C, 65.28; H, 8.90; N, 9.51. Found: C, 65.22; H,
8.96; N, 9.42. IR (KBr, cm-1): 1668 (C6CdO, vs)sym, 1648 (C6Cd
O, vs)asym. UV-vis (MeOH, λmax, nm (ꢀ, M-1 cm-1)): 236
(15 337). 1H NMR (CD3OD, 400 MHz) δ: 1.25 (s, 18H), 177 (s,
3H), 4.05 (s, 3H), 6.81 (s, 2H); 13C NMR (CD3OD, 100 MHz) δ:
185.4, 147.9, 136.5, 73.3, 61.6, 35.3, 29.5, 26.2.
C
16H26N2O3: C, 65.28; H, 8.90; N, 9.51. Found: C, 65.23; H,
9.02; N, 9.56. IR (KBr, cm-1): 1667 (C6CdO, vs)sym, 1645 (C6Cd
O, vs)asym. UV-vis (MeOH, λmax, nm (ꢀ, M-1 cm-1)): 234 (13,-
440). 1H NMR (CD3OD, 400 MHz) δ: 0.82 (t, 3H, J ) 7.46
Hz), 1.22 (s, 18 H), 2.21 (q, 2H, J ) 7.46 Hz), 3.31 (s, 3H),
6.97 (s, 2H), 11.8 (s, 1H); 13C NMR (MeOD) δ: 185.4, 150.2,
133.9, 75.6, 35.6, 32.1, 29.5, 8.12.
O1-Methyl (Z)-1-[4-(2,6-Di-tert-butyl-4-methyl-cyclohexadi-
enonyl)]diazen-1-ium-1,2-diolate (1d ). Anal. Calcd for
C
16H26N2O3: C, 65.28; H, 8.90, N, 9.51. Found: C, 65.02; H,
8.88; N, 9.29. IR (KBr, cm-1): 1667 (C6CdO, vs)sym, 1645 (C6Cd
O, vs)asym. UV-vis (MeOH, λmax, nm (ꢀ, M-1 cm-1)): 238
(11 492). 1H NMR (CD3OD, 400 MHz) δ: 1.25 (s, 18 H), 183
(s, 3H), 3.83 (s, 3H), 6.68 (s, 2H); 13C NMR (CD3OD, 100 MHz)
δ: 185.5, 148.4, 137.7, 65.8, 64.9, 35.2, 29.8, 25.7.
Syn t h esis of O2-Met h yl (Z)-1-[4-(2,6-Di-ter t-b u t yl-4-
eth ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-d iola te (3c).
This compound is prepared as described for 1c (method A) by
treating 3b (0.43 g, 0.0015 mol) with diazomethane to yield a
mixture of O2-methyl (Z)-1-[4-(2,6-di-tert-butyl-4-ethylcyclo-
hexadienonyl)]diazen-1-ium-1,2-diolate (3c) and O1-methyl (Z)-
1-[4-(2,6-di-tert-butyl-4-ethylcyclohexadienonyl)]diazen-1-ium-
1,2-diolate (3d ) isomeric mixture (10:1) as a yellow solid.
Yield: 0.40 g (89%). The product mixture is unstable in air
and found to turn to dark liquid on standing for several hours.
Therefore, no attempts were made to separate the two isomers.
However, the NMR spectroscopic data of the mixture obtained
within 1 h exhibited two sets of peaks corresponding to the
two isomers. UV-vis (MeOH, λmax, nm (ꢀ, M-1 cm-1)): 237-
(13,974).
Syn th esis of Qu in u clid in iu m (Z)-1-[4-(2,6-Di-ter t-bu tyl-
4-m eth ylcycloh exadien on yl)]diazen -1-iu m -1,2-diolate (1e).
To a solution of 1b (0.24 g, 0.00086 mol) in ether (30 mL) was
added dropwise a solution of quinuclidine (0.1 g, 0.0009 mol)
in ether (25 mL) with stirring at 0-5 °C. The precipitated
white solid (1e) was filtered and dried in vacuo over P2O5.
Yield: 0.314 g (96%). Anal. Calcd for C22H37N3O3: C, 67.48;
H, 9.52, N, 10.73. Found: C, 67.24; H, 9.47; N, 10.73. IR (KBr,
cm-1): 1663 (C6CdO, vs)sym, 1640 (C6CdO, vs)asym. UV-vis
(MeOH, λmax, nm (ꢀ, M-1 cm-1)): 246 (12,914). 1H NMR (CDCl3,
400 MHz) δ: 1.24 (s, 18 H), 1.71 (s, 3H), 1.75-1.80 (m, 6H),
2.05 (sept, 1H, J ) 3.15 Hz), 3.17 (t, 6H, J ) 8.10 Hz), 6.95 (s,
2H); 13C NMR (CDCl3, 100 MHz) δ: 186.4, 145.5, 139.6, 67.7,
46.8, 35.0, 29.5, 25.2, 24.1, 20.0
Syn th esis of Tr ieth ylen ed ia m m on iu m (Z)-1-[4-(2,6-Di-
ter t-bu tyl-4-m eth ylcycloh exa d ien on yl)]d ia zen -1-iu m -1,2-
d iola te (1f). This compound was prepared from the reaction
of 1b (0.50 g, 0.0018 mol) with triethylenediamine (DABCO)
(0.22 g, 0.002 mol) by the procedure described above for 1e.
Yield: 0.64 g (91%). Anal. Calcd for C21H36N4O3: C, 64.25; H,
1
O2-Methyl Isomer (3c). H NMR (CDCl3, 400 MHz) δ: 0.77
(t, 3H, J ) 7.42 Hz), 1.22 (s, 18H), 2.15 (q, 2H, J ) 7.52 Hz),
4.02 (s, 3H), 6.75 (s, 2H). 13C NMR (CDCl3, 400 MHz) δ: 185.7,
149.2, 135.2, 76.0, 61.6, 35.5, 29.6, 8.14.
1
O1-Methyl Isomer (3d ). H NMR (CDCl3, 400 MHz) δ: 0.81
(t, 3H, J ) 7.45 Hz) 1.23 (s, 18H) 2.19 (q, 2H, J ) 7.70 Hz),
3.81 (s, 3H), 6.61 (s, 2H). 13C NMR (CDCl3, 400 MHz) δ: 185.8,
150.0, 136.0, 76.2, 64.9, 35.4, 29.5, 8.2.