2636 J. Am. Chem. Soc., Vol. 123, No. 11, 2001
Nicolaides et al.
was tightly stoppered and allowed to stand in a freezer. After 4 days,
absolute Et2O was added to the mixture and stirred. The precipitate
was filtered, washed (Et2O), and dried in vacuo to give 4-azidophen-
ylimidate hydrochloride (700 mg, 89%) as a white solid: mp 118 °C
dec; 1H NMR (CDCl3) δ 1.62 (t, J ) 6.80 Hz, 3H), 4.92 (q, J ) 6.80
Hz, 2H), 7.18 (d, J ) 8.82 Hz, 2H), 8.43 (d, J ) 8.82 Hz, 2H); IR
(KBr disk) ν 3200-2600 (br. s), 2119 (s), 1707 (w), 1603 (s), 1512
(w), 1463 (m), 1444 (m), 1392 (w), 1362 (w), 1303 (m), 1287 (m),
1194 (m), 1132 (w), 1065 (m), 1000 (w), 850 (w), 836 (w), 776 (w),
the resulting mixture was extracted with n-hexane (3 × 10 mL). The
combined hexane portions were dried (Na2SO4), filtered, and evapo-
rated. The residue was purified by gel permeation chromatography to
1
give 4c (83 mg, 43%) as a pale yellow liquid: H NMR (CDCl3) δ
7.02 (d, J ) 8.64 Hz, 2H), 7.09 (d, J ) 8.64 Hz, 2H); 13C NMR (CDCl3)
δ 43, 119, 127, 132, 141; IR (Ar, 13 K) ν 2136 (vs), 2097 (s), 1609
(w), 1590 (w), 1569 (vw), 1560 (vw), 1511 (s), 1422 (vw), 1301 (m),
1290 (m), 1193 (w), 1132 (w), 1032 (w), 1013 (w), 914 (m), 828 (w),
816 (vw), 550 (vw), 544 (w) cm-1; UV (Ar, 13 K) λmax 401, 379, 362,
293 sh, 259, 203 nm.
747 (w) 673 (w) cm-1
.
3-(4-Azidophenyl)-3-bromodiazirine (4d) was prepared following
the literature procedure.37 A mixture of 4-azidophenylamidine hydro-
chloride (440 mg, 2.2 mmol) dimethyl sulfoxide (9.5 mL), LiBr‚H2O
(1.1 g), and n-hexane (5 mL) was stirred at ∼5 °C. A fresh solution of
NaOBr, prepared by the slow addition of bromine (1.1 mL) to a stirred
and cooled (-10 °C) solution of NaOH (2.2 g) and NaBr (6.9 g) in
water (16 mL), was added rapidly to the stirred solution, and the whole
was stirred for an additional hour. The resulting mixture was extracted
with n-hexane (4 × 10 mL). The combined hexane portions were dried
(Na2SO4), filtered, and evaporated. The residue was purified by gel
permeation chromatography to give 4d (420 mg, 79%) as a pale yellow
liquid: 1H NMR (CDCl3) δ 7.01 (d, J ) 8.82 Hz, 2H), 7.12 (d, J )
9.00); IR (Ar, 13 K) ν 2131 (vs), 2094 (s), 1611 (m), 1586 (w), 1571
(w), 1511 (s), 1482 (w), 1421 (w), 1306 (m), 1298 (m), 1288 (m),
1194 (w), 1134 (w), 1122 (w), 1024 (m), 1005 (m), 884 (m), 863 (w),
827 (m), 814 (w), 689 (w), 544 (w), 534 (w) cm-1; UV (Ar, 13 K)
402, 381, 361, 293 sh, 259 nm.
4-Azidophenylamidine hydrochloride was prepared following the
literature procedure.35 To a solution of ethanol saturated with ammonia
was added 4-azidophenylimidate hydrochloride (680 mg, 3.0 mmol).
After stirring for 4 h, the resulting solution was filtered to remove
ammonium chloride. Removal of the solvent and drying of the solid in
vacuo afforded 4-azidophenylamidine hydrochloride (530 mg, 86%)
as a white solid: mp 194 °C (dec); IR (KBr disk) 3450-3000 (br. m),
2113 (s), 1673 (s), 1605 (s), 1491 (m), 1314 (m), 1297 (m), 1202 (w),
1133(w), 837 (w), 736 (w), 712 (w), 658 (w), 534 (w) cm-1
.
4-Azidophenyldiazomethane (4a) was prepared according to a
modified procedure of Rees.36 Thus, a mixture of 4-azidobenzaldehyde
(500 mg, 3.4 mmol) and p-tosylhydrazine (633 mg, 3.4 mmol) in
anhydrous tetrahydrofuran (30 mL) was stirred overnight at room
temperature in the dark. After evaporation of the solvent, 4-azidoben-
zaldehyde tosylhydrazone was obtained as a yellowish solid, which
was used for the next step without further purification. To a stirred
suspension of sodium hydride (60% oil supension, 254 mg, 6.35 mmol)
in anhydrous tetrahydrofuran (10 mL) was added the hydrazone (2.0
g, 6.35 mmol), and the mixture was stirred for 15 min at room
temperature. The precipitate was collected by filtration and washed
thoroughly with anhydrous ether to give sodium 4-azidobenzaldehyde
tosylhydrozonate as a yellowish solid (2.1 g, 98%). The sodium salt
(50 mg, 0.15 mmol) was placed in a micro sublimation apparatus and
heated at 120 °C under 5 × 10-4 Torr. The diazo azido was collected
from a coldfinger as a rather unstable red liquid (18 mg, 75%) and
was immediately used for the matrix photolysis experiments: 1H NMR
(CDCl3) δ 4.94 (s, 1H), 6.91 (d, J ) 2.30 Hz, 2H), 6.96 (d, J ) 2.30
Hz, 2H); IR (Ar, 10 K) ν 2122 (m), 2063 (vs), 1510 (m), 1384 (w),
1300 (m), 1293 (m), 824 (w), 558 (vw) cm-1; UV (Ar, 10 K) λmax 296,
333 nm.
3-(4-Azidophenyl)-3-fluorodiazirine (4b) was prepared following
the literature procedure.37 A mixture of 4d (200 mg, 0.84 mmol),
n-Bu4N+F- (700 mg, 2.7 mmol), and absolute acetonitrile (1 mL) was
stirred at 25 °C in the dark for 4 h. The reaction was quenched with
water (5 mL), and the resulting solution was extracted with n-hexane
(3 × 10 mL). The combined hexane extracts were dried (Na2SO4),
filtered, and evaporated. The residue was purified by gel permeation
chromatography to give 4b (60 mg, 40%) as a pale yellow liquid: 1H
NMR (CDCl3) δ 7.02 (d, J ) 8.82 Hz, 2H), 7.07 (d, J ) 9.00 Hz, 2H);
13C NMR (CDCl3) δ 71 (JC-F ) 262.8 Hz), 119, 126 (JC-F ) 4.36
Hz), 128 (JC-F ) 30.5 Hz), 142; IR (Ar, 13 K) ν 2142 (m), 2134 (s),
2118 (m), 2103 (vs), 1619 (m), 1588 (w), 1564 (w), 1513 (s), 1485
(w), 1425 (w), 1319 (m), 1312 (m), 1302 (m), 1289 (s), 1189 (m),
1169 (m), 1134 (w), 1116 (w), 1031 (w), 1007 (w), 834 (m), 714 (w),
554 (w) cm-1; UV (Ar, 13 K) λmax 396, 375, 356, 292 sh, 283 sh, 264
sh, 258 nm.
4-Nitrenophenylcarbene (3a): IR (Ar, 10 K) ν 1277, 1077, 822,
650 cm-1; UV (Ar, 10K) λmax 263, 379, 397, 419, 437 nm.
4-Nitrenophenylfluorocarbene (3b): IR (Ar, 13 K) ν 1591, 1513,
1388, 1382, 1222, 1188, 1135, 1085, 817, 802, 789, 600, 566 cm-1
;
UV (Ar, 13 K) λmax 264, 402 nm
4-Nitrenophenylchlorocarbene (3c): IR (Ar, 13 K) ν 1569, 1502,
1379, 1083, 948, 913, 820, 712, 569 cm-1; UV (Ar, 13 K) λmax 278,
425 nm.
4-Nitrenophenylbromocarbene (3d): IR (Ar, 13 K) ν 1567, 1498,
1377, 1228, 1170, 1080, 947, 857, 820, 670, 590 cm-1; UV (Ar, 13 K)
λmax 224, 283, 425 nm.
4-Azidophenylchlorocarbene (6-Cl): IR (Ar, 13 K) ν 2124, 1587,
1379, 1294, 1240, 1168, 712 cm-1; UV (Ar, 13 K) λmax 345, 355 nm.
4-Azidophenylbromocarbene (6-Br): IR (Ar, 13 K) ν 2123, 1586,
1293, 1256, 1168, 992, 680 cm-1; UV (Ar, 13 K) λmax 361, 371 nm.
Matrix-Isolation Spectroscopy. Matrix experiments were performed
by means of standard techniques39,40 using an Iwatani Cryo Mini closed-
cycle helium cryostat. For IR experiments, a CsI window was attached
to the copper holder at the bottom of the cold head. Two opposing
ports of a vacuum shroud surrounding the cold head were fit with KBr
with a quartz plate for UV irradiation and a deposition plate for
admitting the sample and matrix gas. For UV experiments, a sapphire
cold window and a quartz outer window were used. The temperature
of the matrix was controlled by an Iwatani TCU-1 controller (gold vs
chromel thermocouple).
Irradiations were carried out with a Wacom 500 W xenon high-
pressure arc lamp. For broad-band irradiation Toshiba cutoff filters were
used (50% transmittance at the specified wavelength).
Supporting Information Available: Total energies (B3LYP,
MCSCF, CASPT2) of 3a-d, 7a-d, and 8 (Tables S1 and S2),
Gaussian archive entries for 3a-d, 6-Cl, 6-Br, 7a-d, and 8
(Table S3), Cartesian coordinates of MCSCF geometries for
3a-d, 7a-d, and 8 (Table S4), and plots of UB3LYP
frequencies for 3a-d (Figure S1) (PDF). This material is
3-(4-Azidophenyl)-3-chlorodiazirine (4c) was prepared following
the literature procedure.38 A mixture of 4-azidophenylamidine hydro-
chloride (200 mg, 1.0 mmol), dimethyl sulfoxide (3.5 mL), LiCl (230
mg), and n-hexane (3 mL) was stirred at ∼5 °C. A hypochlorite solution
(8.0 mL) containing NaCl (1.4 g) was added rapidly to the stirred
solution. After the reaction mixture was stirred for an additional hour,
(35) Dox, A. W. Organic Syntheses; Wiley & Sons: New York, 1945;
Collect. Vol. I, p 5.
(36) Adger, B. M.; Bradbury, S.; Keating, M.; Rees, C. W.; Storr, R.
C.; Williams, M. T. J. Chem. Soc., Perkin Trans. 1 1975, 31.
(37) Moss, R. A.; Terpinski, J.; Cox, D. P.; Denny, D. Z.; Krogh-
Jesperson, K. J. Am. Chem. Soc. 1985, 107, 2743.
JA003709E
(39) Tomioka, H.; Ichikawa, N.; Komatsu, K. J. Am. Chem. Soc. 1992,
114, 6045.
(40) McMahon, R. J.; Chapman, O. L.; Hayes, R. A.; Hess, T. C.;
Krimmer, H. P. J. Am. Chem. Soc. 1985, 107, 7597.
(38) Graham, W. H. J. Am. Chem. Soc. 1965, 87, 4396.