Synthesis of aryl nitroso derivatives by tert-butyl hypochlorite oxidation in homogeneous media. Intermediates for the preparation of high- hyperpolarizability chromophore skeletons

Full text of DOI:10.1021/jo990235x

4976
J . Org. Chem. 1999, 64, 4976-4979
(O2)2(H2O)(hmpa) with H2O2,11 iridium on carbon,12 and
Syn th esis of Ar yl Nitr oso Der iva tives by
pyridinium chlorochromate.13 The heterogeneous oxida-
tion reactions are often slow (frequently requiring several
hours for completion), which can lead to the formation
of the corresponding azoxy derivatives through coupling
of any unconverted hydroxylamine with the nitroso
product.14 Additionally, the slow rate of heterogeneous
oxidation can lead to low product yields in cases where
either the hydroxylamine starting material and/or the
nitroso product has limited stability and, hence, decom-
poses during the course of the reaction. To avoid azoxy
byproduct formation, we have examined the use of tert-
butyl hypochlorite as an inexpensive, homogeneous oxi-
dizing reagent. tert-Butyl hypochlorite has been used in
the oxidation of alcohols to ketones,15 aldehydes to acid
chlorides,16 and sulfides to sulfoxides17 as well as phos-
phines and phosphites to phosphine oxides and phos-
phates,18 respectively. While sodium hypochlorite has
been used to oxidize aromatic N-nitrosohydroxylamines
to aromatic nitroso compounds,19 there is to our knowl-
edge no literature precedent for the use of hypochlorites
in the oxidation of simple aromatic hydroxylamines to
aromatic nitroso products.
ter t-Bu tyl Hyp och lor ite Oxid a tion in
Hom ogen eou s Med ia . In ter m ed ia tes for th e
P r ep a r a tion of High -Hyp er p ola r iza bility
Ch r om op h or e Sk eleton s
M. H. Davey,† V. Y. Lee,‡ R. D. Miller,*,‡ and
T. J . Marks*,†
Department of Chemistry and the Materials Research
Center, Northwestern University, 2145 Sheridan Road,
Evanston, Illinois 60208-3113, and IBM Almaden Research
Center, 650 Harry Road, San J ose, California 95120-6099
Received February 8, 1999
In tr od u ction
Azo-containing chromophores are ubiquitous within
the dye industry.1 They have also been extensively
studied in the area of organic nonlinear optics (NLO),
often displaying higher hyperpolarizabilities and greater
thermal stabilities than their stilbene counterparts.2 In
addition, azo chromophores contained in polymers may
be oriented by polarized light irradiation in a process that
involves both thermal- and photoisomerization of the azo
linkage.3 When irradiated in an electric field, azo chro-
mophore polar orientation can often be induced at tem-
peratures far below the glass transition temperature of
the polymer.4 Although the classical diazonium coupling
reaction5 is often the synthetic method of choice for the
preparation of such chromophores, the Mills6 coupling
reaction between aryl nitroso derivatives and amines (eq
1) offers a valuable complimentary technique, providing
that the prerequisite aromatic nitroso derivatives are
accessible. In certain cases, the azo derivatives cannot
be prepared by diazo coupling procedures due to side
reactions.7
Resu lts a n d Discu ssion
To examine the general applicability of the hypochlo-
rite oxidation procedure for aromatic nitroso synthesis,
we studied comparatively the oxidation of a variety of
phenylhydroxylamines, each substituted with electron-
withdrawing substituents (Schemes 1-3). For purposes
of comparison, we examined both the standard hetero-
geneous hydroxylamine oxidation with iron(III) chloride
and the homogeneous hypochlorite procedure. One gram
of each hydroxylamine was oxidized using each proce-
dure, followed by isolation of the nitroso product and
derivatization for spectral characterization and yield
comparison. The results are compiled in Table 1. Since
all of the nitroso products decompose to some degree
during attempted purification by column chromatography
on silica gel (4c is particularly unstable), the product
yields from each procedure were estimated by subsequent
Mills coupling with p-anisidine and isolation of the stable
azo product. To confirm that the subsequent Mills
coupling reaction was a viable procedure for estimating
the yield of the corresponding nitroso product, compound
4d was first rigorously purified then coupled with p-
The most common procedure for preparing nitroso
derivatives involves the heterogeneous oxidation of the
corresponding hydroxylamine, using iron (III) chloride.8
Other heterogeneous procedures involve silver carbon-
ate,9 tetrabutylammonium cerium(IV) nitrate,10 Mo(O)-
† Northwestern University.
‡ IBM Almaden Research Center.
(1) The Chemistry of Synthetic Dyes; Venkataraman, K., Ed.;
Academic Press: New York, 1970; Vol. 1-7.
(9) Fitzgerald, T. J . J . Med. Chem. 1974, 17, 900.
(10) Muathen, H. A. Indian J . Chem. Sect. B. 1991, 30 (5), 522.
(11) Tollari, S.; Cuscela, M.; Porta, F. J . Chem. Soc., Chem. Com-
mun. 1993, 19, 1510.
(12) Makaryan, I. A.; Savchenko, V. I.; Brikenshtein, Kh. A. Bull.
Acad. Sci. USSR Div. Chem. Sci. (Engl. Transl.) 1983, 32(4), 692.
(13) Wood, W. W.; Wilkin, J . A. Synth. Commun. 1992, 22, 1683.
(14) Zollinger, H. Azo and Diazo Chemistry Aliphatic and Aromatic
Compounds; Interscience: New York, 1961; pp 294-295; translated
by H. E. Nursten.
(15) Stevens, R. V.; Gaeta, F. C. A. J . Am. Chem. Soc. 1977, 99,
6105.
(16) Bergmann, F.; Weizmann, M.; Dimant, E.; Patai, J .; Sz-
muskowicz, J . J . Am.Chem. Soc. 1948, 70, 1612.
(17) J ohnson, C. R.; McCants, D. J r. J . Am. Chem. Soc. 1965, 87,
1109.
(2) (a) Burland, D. M.; Miller, R. D.; Walsh, C. A. Chem. Rev. 1994,
94, 31. (b) Kanis, D. R.; Ratner, M. A.; Marks, T. J . Chem. Rev. 1994,
94, 195.
(3) Neoport, B. S.; Stolbova, O. V. Opt. Spectrosc. 1961, 10, 146.
(4) Sekkat, Z.; Wood, J .; Knoll, W.; Volksen, W.; Miller, R. D.;
Knoesen, A. J . Opt. Soc. Am. B. 1997, 14, 829.
(5) Hegarty, A. F. In The Chemistry of Diazonium and Diazo Groups,
Part 2; Patai, S. Ed.; Wiley: New York, 1978; pp 545-551.
(6) Boyer, J . H. In The Chemistry of the Nitro and Nitroso Groups,
Part 1; Feuer, H., Ed.; Interscience: New York, 1969; pp 278-283.
(7) Miller, R. D.; Burland, D. M.; J urich, M.; Lee, V. Y.; Moylan, C.
R.; Twieg, R. J .; Thackara, J .; Verbiest, T.; Volksen, W.; Walsh, C. A.
In Polymers for Second-Order Nonlinear Optics; Lindsay, G. A., Singer,
K. D., Eds.; ACS Symposium Series 601; American Chemical Society:
Washington, D. C., 1995; pp 130-146.
(18) Denney, D. B.; DiLeone, R. R. J . Am. Chem. Soc. 1962, 84, 4737.
(19) Danzig, M. J .; Matrel, R. F.; Riccitiello, S. R. J . Org. Chem.
1960, 25, 1071.
(8) Entwistle, I. D., Gilkerson, T.; J ohnstone, R. A. W.; Telford, R.
P. Tetrahedron 1978, 34, 213.
10.1021/jo990235x CCC: $18.00 © 1999 American Chemical Society
Published on Web 06/09/1999

Notes
J . Org. Chem., Vol. 64, No. 13, 1999 4977
Ta ble 1. Com p a r ison of Ir on (III) Ch lor id e a n d ter t-Bu tyl
Sch em e 1
Hyp och lor ite Hyd r oxyla m in e Oxid a tion s
Sch em e 2
a
Yields of nitroso derivatives produced upon oxidation were
estimated by the isolation and purification of the corresponding
azo products derived from reaction with p-anisidine.
the formation of a green color characteristic of the nitroso
derivative. To control the oxidation, it was necessary to
utilize dilute reagents (∼10-3 M), cool the reaction
mixture to -78 °C, and rapidly stir to quickly disperse
the oxidant to prevent overoxidation. In each case, the
tert-butyl hypochlorite is added rapidly in one portion via
syringe.
Sch em e 3
The present rapid oxidation procedure is particularly
useful in cases where the starting hydroxylamine is
thermally unstable. For example, 2-(4-(hydroxylamino)-
phenyl)-1,1-dicyanoethylene (3c) is relatively unstable
upon standing at room temperature and must be oxidized
immediately after synthesis in order to produce the
desired nitroso derivative in good yield. In this case, the
slower oxidation rate intrinsic to the heterogeneous iron-
(III) chloride procedure results primarily in the formation
of the corresponding azoxy derivative. In contrast, the
tert-butyl hypochlorite procedure affords a nearly 70%
yield of the desired nitroso product, with no detectible
azoxy formation.
In conclusion, we have developed an efficient, inex-
pensive, high-yielding method of converting arylhydroxy-
lamines to arylnitroso intermediates that are themselves
useful precursors for azo chromophore synthesis. This
method is particularly applicable to the preparation of
nitroso compounds where the standard heterogeneous
oxidation procedures lead primarily to the corresponding
azoxy derivatives. The nitroso products are formed in
high yield, as assayed by isolation of the corresponding
azo derivatives via subsequent Mills coupling. This
technique provides a useful route to a variety of poten-
tially interesting chromophore skeletons.
anisidine in acetic acid. The azo product 5d was isolated
in essentially quantitative yield, thus validating the
assay.
Examination of the data in Table 1 shows that the tert-
butyl hypochlorite procedure results in yields exceeding
those obtained using the heterogeneous technique in
every case. The improvement in yield may be attributed
to the lower reaction temperatures and the significantly
decreased reaction times. The oxidation with tert-butyl
hypochlorite is very rapid and is essentially complete
after addition of the oxidizing reagent, as evidenced by
Exp er im en ta l Section
1H NMR and 13C NMR spectra were measured at 250 and 63
MHz, respectively, and the chemical shifts are referenced to
tetramethylsilane (TMS). Melting points are reported as the
temperature at the peak of the melting point endotherm,
measured by differential scanning calorimetry (DSC) at
a

4978 J . Org. Chem., Vol. 64, No. 13, 1999
Notes
heating rate of 20 °C/min. All chromatography was performed
as flash column chromatography.20 All chemicals were obtained
from Aldrich Chemical, except where indicated. Commercial
grade sodium hypochlorite (Clorox) was used for the preparation
of tert-butyl hypochlorite.
Rea gen ts. tert-Butyl hypochlorite was freshly prepared as
described in the literature.21 The reagent was standardized using
potassium iodide followed by titration of iodine using 0.1 N
sodium thiosulfate. 2-(4-Nitrophenyl)-1,1-dicyanoethylene (1),22
(4-nitrophenyl)hydroxylamine (3a ),8 4-hydroxylaminobenzoni-
trile (3b),23 and methyl 4-(hydroxylamino)benzoate (3e)24 were
prepared using methods described in the literature.
under argon. Sodium hypophosphite nonahydrate (5.89 g, 0.0556
mol) was dissolved in 30 mL of distilled water and added to the
THF solution. The solution was cooled with an ice/water bath,
10% Pd/C (0.60 g) was added, and the solution was stirred
vigorously while the reaction progress was monitored by TLC
(5% ethyl acetate/dichloromethane). When the starting material
was consumed (45 min), the solution was filtered through Celite,
100 mL of ethyl acetate was added, and the organic phase was
washed with distilled water (3×). The organic layer was then
separated, dried over MgSO4, filtered, adsorbed onto silica gel,
and chromatographed (gradient elution: 0%, 5%, 10% ethyl
acetate/methylene chloride). The bright orange product was used
without further purification: yield 5.19 g (91%); mp 169 °C dec;
1H NMR (DMSO-d6) δ 9.49 (s, 1H, NHOH), 8.95 (s, 1H, NHOH),
7.57 (m, 3H, Ar), 7.43 (d, 2H, J ) 7 Hz, Ar), 7.32 (d, 2H, J ) 9
Hz, Ar), 6.82 (d, 2H, J ) 9 Hz, Ar); 13C NMR (63 MHz, DMSO-
d6) δ 173.40, 155.93, 136.68, 132.87, 131.90, 130.38, 128.67,
124.02, 115.82, 115.46, 110.62, 74.44; IR (KBr) 3500-3350, 2231,
1605, 1513, 1347 cm-1; UV (THF) λmax, nm (ꢀ) 380 (26,380); EI
MS m/z 261 (M+). Anal. Calcd for C16H11N3O: C, 73.55; H, 4.24;
N, 16.08. Found: C, 73.75; H, 4.27; N, 15.78.
Gen er a l P r oced u r es for th e P r ep a r a tion of Nitr oso
Der iva tives. A. Ir on (III) Ch lor id e Sta n d a r d P r oced u r e.
Iron(III) chloride (5.5 equiv) was dissolved in 125 g of ice/water
and cooled with an ice/water bath to 20 °C. In a separate flask,
1.0 g of the hydroxylamine was dissolved in 40 mL of ethanol
and added dropwise to the stirring iron(III) chloride solution
across 20-30 min. The solution was then stirred an additional
30 min and filtered through Celite, 200 mL of ethyl acetate was
added, and the solution was extracted 3× with water. The
organic layer was dried over Na2SO4, filtered, and the solvent
was removed under reduced pressure. The crude product was
used for derivatization without further purification.
2-(4-Nitr op h en yl)-2-p h en yl-1,1-d icya n oeth ylen e (2). In a
1 L three-necked flask equipped with a water-cooled condenser,
dropping funnel, thermometer, and magnetic stirring bar, 4-ni-
trobenzophenone (22.72 g, 0.100 mol) and malononitrile (16.52
g, 0.250 mol) were dissolved in 225 mL of 1,2-dichloroethane.
After the mixture was cooled to 5 °C (ice/water bath) under
argon, titanium tetrachloride (40 mL, 0.365 mol) was added
dropwise over 30 min (bright yellow color). While the solution
was maintained at 5 °C, pyridine (80 mL, 0.989 mol) was added
dropwise over 30 min. Upon completion of addition, the cooling
bath was removed, and the solution was heated to reflux
overnight. After the mixture was cooled to room temperature,
the reaction mixture was filtered through Celite. The filtered
solids were slurried with chloroform, and the solution was
filtered and washed 3× with 10% HCl (aq) and 2× with 10%
NaHCO3. The organic extracts were combined and dried over
MgSO4. After filtration, the filtrate was adsorbed onto silica gel
and chromatographed using 20% ethyl acetate/hexane. Colorless
needles of 2 were obtained upon recrystallization from 2-pro-
1
panol: yield, 18.24 g (66%); mp 105 °C; H NMR (DMSO-d6) δ
8.38 (d, 2H, J ) 9 Hz), 7.77 (d, 2H, J ) 10 Hz), 7.57 (m, 5H); 13
C
B. ter t-Bu tyl Hyp och lor ite Sta n d a r d P r oced u r e. The
hydroxylamine derivative (1.0 g) was placed into a three-necked
NMR (DMSO-d6) δ 171.46, 149.27, 141.98, 135.19, 132.90,
131.50, 130.11, 129.04, 123.92, 113.75, 113.63, 84.66; IR (KBr)
2236, 1569, 1522, 1352, 1331 cm-1; UV (THF) λmax, nm (ꢀ) 318
(13 790). Anal. Calcd for C16H9N3O2: C, 69.81; H, 3.30; N, 15.27.
Found: C, 70.15; H, 3.39; N 15.31.
1-L flask fitted with
a gas inlet valve, thermometer, and
magnetic stirrer and was dissolved in 500 mL of diethyl ether
or THF under argon. The solution was cooled to -78 °C and
stirred rapidly during the addition of 1.0 equiv of tert-butyl
hypochlorite. The solution was allowed to stir for an additional
5 min, the cooling bath was removed, and the solution was
allowed to warm to -20 °C. The solvent was removed under
reduced pressure (25 mmHg) at 0 °C, and the product was dried
under high vacuum (0.1 mmHg) at room temperature. The crude
product was converted to the corresponding azo derivative
without further purification.
4-Nitr on itr osoben zen e (4a ). Using method B and 3a in
diethyl ether, the crude product was obtained in 97% yield and
was used without further purification after spectral and chro-
matographic comparison with an authentic sample.25
4-Nitr osoben zon itr ile (4b). Using method B and 3b in
diethyl ether, the crude product was obtained in 99% yield and
was used without further purification after spectral and chro-
matographic comparison with an authentic sample.26
2-(4-(Hyd r oxyla m in o)p h en yl)-1,1-d icya n oeth ylen e (3c).
Into a three-necked flask equipped with an overhead stirrer,
were placed 70 mL of THF and 8.00 g (0.04 mol) of 1 under
argon. Sodium hypophosphite nonahydrate (10.6 g, 0.10 mol) was
dissolved in 70 mL of distilled water and added to the THF
solution. After the solution was cooled with an ice/water bath,
10% Pd/C (0.60 g) was added in small portions. Upon completion
of the addition, the cooling bath was removed, and the solution
was heated to 40-45 °C, while stirring vigorously, and the
reaction progress was monitored by TLC (40% THF/hexane).
When no further nitro compound was present (2 h), the solution
was filtered through Celite. Ethyl acetate (150 mL) was added,
the solution washed with distilled water (3×), and the organic
phase dried over Na2SO4. Next the organic phase was filtered,
and the solvent was removed under reduced pressure. The
residue was redissolved in 250 mL of THF and filtered through
Celite. The filtrate was then chromatographed on silica gel
(gradient elution: 40, 60, 80% ethyl acetate/hexane). The solvent
was removed under reduced pressure, the residue was dissolved
in THF and filtered, and toluene was added. The solution was
concentrated until precipitation occurred, and the solid was then
collected and dried. The resulting orange solid was used without
further purification: yield 6.1 g (82%); mp 132-133 °C; 1H NMR
(DMSO-d6) δ 9.87 (s, 1H, NHOH), 9.21 (s, 1H, NHOH), 8.06 (s,
1H, vinyl), 7.81 (d, 2H, J ) 9 Hz, Ar), 6.82 (d, 2H, J ) 9 Hz, Ar);
13C NMR (DMSO-d6) δ 159.31, 156.29, 133.67, 120.59, 116.06,
115.23, 110.38, 69.92; IR (KBr) 3500-3100, 2225, 1612, 1517
cm-1; EI MS m/z 185 (M+).
2-(4-Nit r osop h en yl)-1,1-d icya n oet h ylen e (4c). Using
method B and 3c in THF, the crude product was obtained in
1
82% yield: mp 122-124 °C; H NMR (DMSO-d6) δ 8.70 (s, 1H,
vinyl), 8.24 (d, 2H, J ) 9 Hz, Ar), 8.13 (d, 2H, J ) 9 Hz, Ar); IR
(KBr) 2230, 1592, 1566, 1421, 1297 cm-1; EI MS m/z 183 (M+).
2-(4-Nitr osop h en yl)-2-p h en yl-1,1-d icya n oeth ylen e (4d ).
Using method B and 3d in diethyl ether, the crude product was
1
obtained in 95% yield: mp 105 °C; H NMR (DMSO-d6) δ 8.10
(d, 2H, J ) 7 Hz, Ar), 7.87 (d, 2H, J ) 7 Hz, Ar), 7.57 (m, 5H,
Ar); 13C NMR (DMSO-d6) δ 171.82, 163.92, 142.70, 135.15,
132.87, 131.92, 130.11, 129.05, 120.67, 113.80, 113.70, 84.54; IR
(KBr) 2231, 1269, 1159 cm-1; UV (THF) λmax, nm (ꢀ) 294 (18 157);
EI MS m/z 259 (M+). Anal. Calcd for C16H9N3O: C, 74.12; H,
3.50; N, 16.21. Found: C, 74.04; H, 3.88; N, 15.95.
2-(4-(Hyd r oxyla m in o)p h en yl)-2-p h en yl-1,1-d icya n oeth -
ylen e (3d ). Into a three-necked flask equipped with an overhead
stirrer were placed 40 mL of THF and 6.01 g (0.0218 mol) of 2
Meth yl 4-n itr osoben zoa te (4e). Using method B and 3e in
THF, the crude product was obtained in 82% yield: mp 130 °C
(lit.25 mp 130 °C); 1H NMR (CDCl3) δ 8.29 (d, 2H, J ) 9 Hz, Ar),
7.91 (d, 2H, J ) 7 Hz, Ar), 3.96 (s, 3H, OCH3); 13C NMR (CDCl3)
(20) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923.
(21) Mintz, M. J .; Walling, C. Org. Synth., Coll. Vol. V 1973, 183.
(22) Sturz, H. G.; Noller, C. R. J . Am. Chem. Soc. 1949, 71, 2949.
(23) Yanada, K.; Yamaguchi, H.; Meguri, H.; Uchida, S. J . Chem.
Soc. Chem. Commun. 1986, 22, 1655.
(25) Defoin, A.; Geffroy, G.; Noued, D. L.; Spileers, D.; Streith, J .
Helv. Chim. Acta. 1989, 72, 1199.
(24) Huntress, E. H.; Lesslie, T. E., Hearon, W. M. J . Am. Chem.
Soc. 1956, 78, 419.
(26) Herndon, J . W.; McMullen, L. A. J . Organomet. Chem. 1989,
368, 83.

Notes
J . Org. Chem., Vol. 64, No. 13, 1999 4979
δ 165.74, 164.39, 135.21, 131.05, 120.39, 52.77; IR (KBr) 1734,
1443, 1419, 1256, 1029 cm-1; UV (CHCl3) λmax, nm (ꢀ) 288
(15 310).
C
17H12N4O: C, 70.82; H, 4.19; N, 19.43. Found: C, 70.88; H,
4.23; N, 19.17.
2-(4-((4-Meth oxyp h en yl)d ia zen yl)p h en yl)-2-p h en yl-1,1-
d icya n oeth ylen e (5d ). Compound 4d and p-anisidine were
coupled as described. A small amount of THF was added to the
acetic acid solution to improve solubility. Flash chromatography
(33% ethyl acetate/hexane) and recrystallization from ethanol
Gen er a l P r oced u r e for th e P r ep a r a tion of Azo Der iva -
tives fr om Ar yl Nitr oso Com p ou n d s. Solid crude nitroso
compounds (1.0 equiv) were added to a solution of p-anisidine
(2.0 equiv) dissolved in glacial acetic acid and stirred for 3-24
h at room temperature. The reaction progress was monitored
by TLC analysis (ethyl acetate/hexane). After the disappearance
of the starting material, ethyl acetate was then added to the
reaction mixture, the organic phase was washed with water (3×),
and dried over MgSO4. After filtration, the resulting mixture
was purified by flash chromatography on silica gel and recrystal-
lized.
1
gave 5d in 96% yield: mp 144-145 °C; H NMR (DMSO-d6) δ
7.95 (m, 4H, Ar), 7.62 (m, 7H, Ar), 7.16 (d, 2H, J ) 9 Hz, Ar),
3.87 (s, 3H, OCH3); 13C NMR (DMSO-d6) δ 172.99, 162.77,
153.96, 146.32, 137.55, 135.78, 132.68, 131.72, 130.28, 128.95,
125.14, 122.40, 114.80, 114.21, 82.52, 55.78; IR (KBr) 2231, 1605,
1507, 1259 cm-1; UV (THF) λmax, nm (ꢀ) 380 (50 789). Anal. Calcd
for C23H16N4O: C, 75.81; H, 4.43; N, 15.37. Found: C, 76.19; H,
4.72; N, 15.34.
(4-Meth oxyp h en yl)(4-n itr op h en yl)d ia zen e (5a ). 5a was
purified by flash chromatography over silica gel (33% ethyl
acetate/hexane) followed by recrystallization from ethanol (89%).
The spectral properties were identical to those of an authentic
Met h yl 4-((4-m et h oxyp h en yl)d ia zen yl)b en zoa t e (5e).
Compound 4e and p-anisidine were coupled as described, adding
a small quantity of THF to improve solubility. Flash chroma-
tography (33% ethyl acetate/hexane) followed by recrystallization
from ethanol gave 5e in 68% yield: mp 172 °C (lit.29 mp 170-
171 °C);29 1H NMR (CDCl3) δ 8.15 (d, 2H, J ) 9 Hz, Ar), 7.93 (d,
2H, J ) 9 Hz, Ar), 7.88 (d, 2H, J ) 9 Hz, Ar), 7.00 (d, 2H, J )
9 Hz, Ar), 3.93 (s, 3H, CO2CH3), 3.87 (s, 3H, OCH3); 13C NMR
(DMSO-d6) δ 166.63, 162.68, 155.36, 147.02, 131.18, 130.59,
125.20, 122.33, 114.33, 55.62, 52.27; IR (KBr) 1717, 1611, 1501,
1437, 1262, 1029 cm-1; UV (THF) λmax, nm (ꢀ) 358 (26 010).
29
sample.27,
4-((4-Meth oxyp h en yl)d ia zen yl)ben zon itr ile (5b). 5b was
purified by flash chromatography over silica gel (33% ethyl
acetate/hexane) followed by recrytallization from ethanol (95%).
The spectral properties were identical to those of an authentic
sample.28
2-(4-((4-Meth oxyp h en yl)d ia zen yl)p h en yl)-1,1-d icya n oet-
h ylen e (5c). The product 5c was purified by flash chromatog-
raphy over silica gel (20% ethyl acetate/hexane) followed by
recrystallization from ethanol (70%): mp 174-175 °C; 1H NMR
(DMSO-d6) δ 8.59 (s, 1H, vinyl), 8.12 (d, 2H, J ) 9 Hz, Ar), 7.99
(d, 2H, J ) 9 Hz, Ar), 7.93 (d, 2H, J ) 9 Hz, Ar), 7.15 (d, 2H, J
) 9 Hz, Ar), 3.87 (s, 3H, OCH3); 13C NMR (DMSO-d6) δ 162.96,
160.21, 154.64, 146.33, 132.80, 131.97, 125.31, 123.02, 114.84,
114.21, 113.29, 82.12, 55.80; IR (KBr) 2222, 1583, 1500, 1402
cm-1; UV (THF) λmax, nm (ꢀ) 392 (46 210). Anal. Calcd for
Ack n ow led gm en t. Partial financial support for this
research was provided by the Air Force Office of
Scientific Research (Contract F-49620-94-1-0323) and
the Office of Naval Research through the CAMP MURI
program (Contract N00014-95-1-1319). M. H. Davey also
acknowledges partial financial support from IBM Corp.
as a visiting scholar.
(27) Neumann, W. P.; Wicenec, C. Chem. Ber. 1991, 124 (10), 2297.
(28) Lazareva et al., J . Org. Chem. USSR (Engl. Transl.) 1976, 12,
144.
(29) Shimao, I.; Oae, S. Bull. Chem. Soc. J pn. 1983, 56 (2), 643.
J O990235X