Oxidation of nitrobenzylic carbanions with dimethyldioxirane. New synthesis of quinomethanes and nitrobenzylic carbinols. First examples of methylation of carbanions with dimethyldioxirane

Article abstract of DOI:10.1021/jo010055z

The reaction of nitrobenzylic carbanions with dimethyldioxirane (DMD) results in oxidation at the carbanion center or at the nitronate center to give nitrobenzylic carbinols or quinomethanes, respectively. Minor amounts of the methylation products are also formed. Both of these processes were observed for carbanions of (p-nitroaryl)diarylmethanes. The outcome of the oxidation process is very sensitive to the reaction conditions.

Full text of DOI:10.1021/jo010055z

5022
J . Org. Chem. 2001, 66, 5022-5026
Oxid a tion of Nitr oben zylic Ca r ba n ion s w ith Dim eth yld ioxir a n e.
New Syn th esis of Qu in om eth a n es a n d Nitr oben zylic Ca r bin ols.
F ir st Exa m p les of Meth yla tion of Ca r ba n ion s w ith
Dim eth yld ioxir a n e
Mieczysław Ma¸kosza,*,† Waldemar Adam,‡ Cong-Gui Zhao,‡ and Marek Surowiec†
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/ 52, 01-224 Warsaw, Poland,
and Institut fu¨r Organische Chemie, Universit Wu¨rzburg, Am Hubland, D-97074 Wu¨rzburg, Germany
icho-s@icho.edu.pl
Received J anuary 17, 2001
The reaction of nitrobenzylic carbanions with dimethyldioxirane (DMD) results in oxidation at the
carbanion center or at the nitronate center to give nitrobenzylic carbinols or quinomethanes,
respectively. Minor amounts of the methylation products are also formed. Both of these processes
were observed for carbanions of (p-nitroaryl)diarylmethanes. The outcome of the oxidation process
is very sensitive to the reaction conditions.
Sch em e 1. Oxid a tion of th e σH Ad d u cts Der ived
fr om th e 2-P h en ylp r op ion itr ile Ca r ba n ion a n d
Nitr oa r en es by P ota ssiu m P er m a n ga n a te in
Liqu id Am m on ia or by DMD
In tr od u ction
The oxidation of σH adducts of the 2-phenylpropionitrile
carbanion with nitroarenes by potassium permanganate
in liquid ammonia results in the formation of p-nitro-
arylated nitrilessproducts of the oxidative nucleophilic
substitution of hydrogen in nitroarenes.1 In contrast, the
oxidation of these σH adducts by dimethyldioxirane
(DMD) in THF affords para-substituted phenols (Scheme
1).2
In the case of the oxidation with permanganate, the
oxidation process takes place at the site at which the
nucleophile was added to the nitrobenzene ring. This
process is sensitive to the steric hindrance of the sub-
stituents located in the vicinity of the addition site and
proceeds with a large kinetic isotope effect kH/kD ) 9.79
(at -70 oC).3 Both of these experimental observations
indicate that the oxidation of the σH adducts with KMnO4
proceeds via attack of the oxidant on the site of the
nucleophilic addition. In contrast, the bulky substituents
in the vicinity of the addition site do not affect the
oxidation of the σH adducts by DMD, and the kinetic
isotope effect for the oxidation of the σH and σD adducts
is negligible, that is kH/kD ) 1.01.2 These observations
indicate that the DMD oxidant, contrary to KMnO4,
attacks the negatively charged nitronate group of the σH
adducts. A similar reactivity has been proposed for the
oxidation of nitronate anions to ketones by DMD, an
oxidative variant of the Nef reaction.4
Sch em e 2. Exp ected Oxid a tion of Nitr oben zylic
Ca r ba n ion s to Qu in om eth a n es by DMD
Since the distribution of the negative charge in the
p-nitrobenzylic carbanions should be similar to that in
the anionic σH adducts, we expected that the oxidation
of the former by DMD should convert the nitronate
functionality into a carbonyl group and, thus, give
quinomethane derivatives (Scheme 2).
* To whom correspondence should be addressed. Fax +48(22)-
6326681.
† Polish Academy of Sciences.
‡ Universit Wu¨rzburg. Fax: +499318884756. http://www-organi-
k.chemie.uni-wuerzburg.de.
Previously it was observed that typical oxidants such
-
as O2, H2O2, and MnO4 react with these carbanions to
(1) (a) Ma¸kosza, M.; Stalin˜ski, K. Chem. Eur. J . 1997, 3, 2025. (b)
Ma¸kosza, M.; Stalin˜ski, K. Tetrahedron 1998, 54, 8797. (c) Ma¸kosza,
M.; Stalin˜ski, K. Synthesis 1998, 11, 1631.
(2) Adam, W.; Ma¸kosza, M.; Stalin˜ski, K.; Zhao, C.-G. J . Org. Chem.
1998, 63, 4390. (b) Adam, W.; Ma¸kosza, M.; Zhao, C.-G.; Surowiec, M.
J . Org. Chem. 2000, 65, 1099.
give hydroxy compounds and products of their further
transformations, such as alcohols, aldehydes, ketones,
carboxylic acids, etc.5,6 Herein we report our results on
(3) Ma¸kosza, M.; Stalin˜ski, K. Tetrahedron Lett. 1998, 39, 3575.
(4) Adam, W.; Ma¸kosza, M.; Saha-Moller, C. R.; Zhao, C.-G. Synlett
1998, 124, 1335.
(5) Lawrence, N. J .; Lamarche, O.; Thurrab, N. J . Chem. Soc., Chem.
Commun. 1999, 689.
(6) Ma¸kosza, M., unpublished results.
10.1021/jo010055z CCC: $20.00 © 2001 American Chemical Society
Published on Web 06/22/2001

Oxidation of Nitrobenzylic Carbanions
J . Org. Chem., Vol. 66, No. 15, 2001 5023
Sch em e 3. Oxid a tion of Nitr oben zylic
Ca r ba n ion s to th e Cor r esp on d in g Hyd r oxy
Com p ou n d s by DMD
Sch em e 4. Oxid a tion of
Dip h en yl(4-n itr op h en yl)m eth a n es by DMD
Ta ble 1. Oxid a tion of Nitr oben zylic Ca r ba n ion s w ith
DMD to th e Cor r esp on d in g Hyd r oxy Com p ou n d sa
nitroarene
position
of CHXY
convn
(%)
yield
product (%)
Z
X
Y
1a
1b
H
H
4
4
2
2
4
4
4
H
Me
H
H
Me
Ph
SO2Ph
SO2Ph
SO2Tol
SO2Ph
Me
63
50
74
78
87
3a
3b
3c
3d
2e
2f
60
33
30
43
85
63
99
b
1c (CH)4
1d 4-Cl
1e
1f
On the other hand, treatment of the carbanion of (4-
nitrophenyl)diphenylmethane (4a ) with DMD (Scheme
4) results in the formation of the expected quinone-
methane 5a as the major product. Additionally, (4-
nitrophenyl)diphenyl carbinol (6a ), product of the oxi-
dation of the carbanion and, suprisingly, 1,1-diphenyl-
1-(4-nitrophenyl)ethane (7a ), were also isolated. The
unusual methylation of the carbanion by dimethyl-
dioxirane will be discussed later.
H
H
H
COOMe 100
99
1g
9-fluorenyl
2g
a
Run in THF at ambient temperature (ca. 20 °C). b(1-Nitro-2-
naphthyl)methyl 4-tolyl sulfone.
the DMD oxidation of nitrobenzylic carbanions which
results in the formation of hydroxy compounds and the
corresponding quinomethanes.
Although the structure of the carbanion 4a - is similar
to that derived from the 9-fluorenyl derivative 1g, the
latter is oxidized by DMD only to the corresponding
carbinol 2g (Table 1), whereas under the same conditions,
carbanion 4a - produces the quinomethane 5a as the
major product. In the carbanion derived from 1g, the
fluorenyl structure obliges a planar geometry of the two
benzene rings, while in the benzhydryl carbanion 4a -,
the phenyl groups are twisted out from planarity. The
different behavior of these rather similar carbanions, 4a -
and 1g-, suggests that the oxidation by DMD is sensitive
to the steric hindrance at the reaction site. It appears
that the oxidation of the benzylic carbanions by DMD at
the carbanionic center is a facile process when it is
planar, as is the case of substrate 1g. In contrast, for the
carbanion 4a -, the phenyl groups are twisted out of
planarity, and therefore the oxidation of the carbanion
center by DMD is hindered due to steric reasons, and
DMD reacts preferentially at the more exposed nitronate
functionality.
Resu lts a n d Discu ssion
The precursors of the nitrobenzylic carbanions 1 are
readily available from nitroarenes by vicarious nucleo-
philic substitution, VNS with chloroalkyl sulfones, esters
of R-chloroalkanoic acids, etc.7 The carbanions were
generated from the substituted nitroarenes 1 by reaction
with t-BuOK (2 equiv of the base were advantageous, as
assessed through optimization of the experimental condi-
tions) and submitted to oxidation by DMD (Scheme 3),
which was prepared in the standard way.8 The results
of these experiments are summarized in Table 1.
Thus, when the carbanions of p-nitrobenzyl phenyl
sulfone (1a ) and 1-(4-nitrophenyl)ethyl phenyl sulfone
(1b) were treated with DMD, instead of the expected
quinomethanes, p-nitrobenzaldehyde (3a ) and p-nitro-
acetophenone (3b) were obtained as main products.
Clearly, similar to the oxidation of these carbanions with
other oxidants, the reaction proceeded at the carbanionic
site with the formation of corresponding hydroxy deriva-
tives 2. After the elimination of the sufinic acid from the
intermediates 2, aldehydes and ketones 3 are formed as
final products.6 The oxidation of these carbanions by the
3,3-pentamethyleneoxaziridine, an analogue of DMD,
took place also at the carbanionic site.9 The oxidation of
the carbanions of methyl R-(4-nitrophenyl)-R-phenylac-
etate (1f), 4-isopropyl-nitrobenzene (1e), and 9-(4-nitro-
phenyl)fluorene (1g) by DMD result in the formation of
the corresponding hydroxy compounds 2f, 2e, and 2g
(Table 1).
Since there are a few competing reactions proceeding
when the nitrobenzylic carbanion of 4a is treated with
DMD, we could expect that the final outcome of the
oxidation process should be sensitive to the reaction
conditions. For this purpose, the products distribution
pattern of the nitrobenzylic carbanion 4a - oxidation with
DMD was examined as a function of the solvent and
countercation (Table 2).
As the data in Table 2 indicate, the nature of the
carbanion-cation pair affects substantially the product
distribution, however, in a complex way. Thus, the
oxidation of the K+ salt gave the highest yield of the
quinomethane 5a in the nonpolar toluene (entry 8) and
in moderately polar THF (entry 3) solvents. On the other
hand, the oxidation of the carbanion 4a - in THF with
Bu4N+ and ClMg+ as countercations gave only the
hydroxylation product 6a (entries 5 and 4), whereas the
oxidation of the Na+ and Li+ salts in THF gave appreciate
(7) Golin˜ski, J .; Ma¸kosza, M. Tetrahedron Lett. 1978, 3495. (b)
Ma¸kosza, M.; Glinka, T. J . Org. Chem. 1983, 48, 3860. (c) Mudryk, B.;
Ma¸kosza, M. Synthesis 1988, 1007. (d) Ma¸kosza, M.; Winiarski, J . Acc.
Chem. Res. 1987, 20, 282. (e) Ma¸kosza, M.; Wojciechowski, K. Liebigs
Ann. Rec. 1997, 1805.
(8) Adam, W.; Białas, J .; Hadjiarapoglou, L. Chem. Ber. 1991, 124,
2377.
(9) Wulf, J . P.; Sienkiwicz, K.; Ma¸kosza, M.; Schmitz, E. Liebigs Ann.
Chem. 1991, 537.

5024 J . Org. Chem., Vol. 66, No. 15, 2001
Adam et al.
Sch em e 5. P r op osed Mech a n ism for th e
Ta ble 2. Th e P r od u ct Ra tio in th e DMD Oxid a tion of th e
Nitr oben zylic Ca r ba n ion of 4a a
Meth yla tion of Nitr oben zylic Ca r ba n ion s by DMD
product/yield (%)b
entry cation M+
solvent
THF
THF
THF
THF
THF
DMF
3:1 THF/DMF
toluene
convn
5a
6a
7a
1
2
3
4
5
6
7
8
Li+
83
88
95
96
97
93
91
90
17
33
48
63
47
26
80
95
60
45
33
16
16
17
3
0
8
Na+
K+
ClMg+
nBu4N+
K+
traces
0
29
37
51
K+
14
15
K+
a
Run at ambient temperature (ca. 20 °C). bIsolated products
by preparative TLC and calculated for complete conversion.
Ta ble 3. Oxid a tion of P ota ssiu m Sa lts of
Dip h en yl(n itr oa r yl)m eth a n es Ca r ba n ion s 4 by DMDa
substrates
Ar
products/yields (%)b
Z
convn (%)
5
6
4a
Ph
H
(CH)4
2-I
2-MeO
2-Cl
3-MeO
3-Cl
95
100
94
86
93
99
83
100
100
80
5a /51
5b/91
5c/33
5d /58
5e/58
5f/44
5g/61
5h /64
5i/40
5j/75
6a /28c
6b/traces
6c/38
6d /36
6e/30
6f/13e
6g/10
-
4bd Ph
In a few cases, the oxidation of the nitrobenzylic
carbanions by DMD was accompanied by the formation
of significant quantity (up to 16%) of 1,1-diaryl-1-(4-
nitroarene)ethane 7, the methylation product of the
carbanions (Table 3). In three cases, the methylation
products 7a , 7f, and 7i were isolated and fully character-
ized. A similar unusual reaction has been reported in the
case of oxidation by the nitroxide radical of methyl-
(trifluoromethyl)dioxirane and by hydrazine derivatives
of DMD.11,12 Presumably, this reaction proceeds via single
electron transfer (SET) from the carbanion to DMD,
followed by further transformations of the intermediary
radical species, as shown in Scheme 5.
4c
4d
4e
4f
4g
4h
4i
Ph
Ph
Ph
Ph
Ph
Ph
3-CN
f
4-Cl-phenyl 3-MeO
1-naphthyl
6i/26
4j
H
6j/20
a
Run in THF at ambient temperature (ca. 20 °C). bIsolated
products by preparative TLC, calculated for complete conversion.
cAlso 18% of 7a . dReaction performed in DMF. eAlso 30% of 7f.
fAlso 33% of 7i.
Ta ble 4. Oxid a tion of 4a - w ith Va r iou s Oxid a n ts
convn
(%)
products/yieldsa
(%)
oxidant
Con clu sion s
DMD
95
98
85
99
5a /51
5a /0
5a /0
5a /0
6a /26
6a /76
6a /91
6a /95
3,3-pentamethylene-oxaziridine
H2O2
Oxidation of the nitrobenzylic carbanions with di-
methyldioxirane proceeds at the carbanion center giving
hydroxy compouds and at the nitronate group producing
quinomethanes. The reaction course is governed by the
substituents at the carbanion center and the reaction
conditions: solvents and countercation. In some cases a
peculiar reaction of methylation of the carbanions was
observed.
-
nBu4N+ MnO4
a
Isolated products by preparative TLC, calculated for complete
conversion.
amounts of the quinomethane 5a , in parallel with
carbinol 6a as a main product (entries 1 and 2).
Since the carbanion 4a - upon the oxidation with DMD
gave the expected quinomethane 5a as the major product,
a number of other (4-nitroarene)diarylmethanes 4b-j
were prepared,10 in anticipation that the corresponding
carbanions would give the desired quinomethanes upon
the oxidation by DMD. Indeed, the treatment of the
carbanions 4b-j with DMD, under the conditions in
which the oxidation of 4a - gave mainly 5a , led to the
corresponding quinomethanes 5 as the major products
(Table 3). Particularly the carbanions 4b- and 4j- af-
forded the expected quinomethanes 5b and 5j in high
yields.
Exp er im en ta l Section
Gen er a l Asp ects. Melting points were uncorrected. 1H
NMR spectra were recorded on a Varian Gemini 200 (200
MHz) or Bruker AMX (500 MHz) instruments. Chemical shifts
are reported in ppm relative to TMS as internal standard;
coupling constants J are in Hz. EIMS HR were measured on
a AMD 604 spectrometer. THF was distilled over potassium
benzophenone ketyl before reaction, and DMF was distilled
over calcium hydride and stored over molecules sieves. Potas-
sium tert-butoxide was reagent grade, purchased from Fluka,
and was handled in a drybox under argon gas. Starting
nitroarenes: 1a -d and 1g were prepared according to the
standard procedure,7 1h was prepared according procedure
described by Wojciechowski,13 1e was a commercial sample,
and 4a -j were prepared according to the reported procedure.10
Dimethyldioxirane (DMD) was prepared according to standard
procedure.8
Oxidation of carbanion 4a - with other oxidants pro-
ceeds only at the carbanion center to give the correspond-
ing carbinol 6a , without even traces of the quinomethane
5a (Table 4). This emphasizes the unique oxidative
nature of the DMD, which can react at the nitronate
functionality and the nitrobenzylic carbanion site. The
quinomethane/carbinol product ratio provides a delicate
measure of these two competitive oxidation processes.
(11) Adam, W.; Bottle, S. E., Mello, R. J . Chem. Soc., Chem.
Commun. 1991, 771.
(12) Nelsen, S. F.; Scamehorn, R. G.; De Felippis, J .; Wang, Y. J .
Org. Chem. 1993, 58, 1657.
(13) Wojciechowski, K. Bull. Pol. Ac. Chem. 1988, 36235.
(10) Ma¸kosza, M.; Voskresenski, S.; Surowiec, M. Synthesis 2000,
1237.

Oxidation of Nitrobenzylic Carbanions
J . Org. Chem., Vol. 66, No. 15, 2001 5025
Gen er a l P r oced u r e for th e Oxid a tion of th e Nitr oben -
zylic Ca r ba n ion s by DMD. The appropriate carbanion
precursor (1 mmol) was added to a solution of t-BuOK (2 mmol,
224 mg) in THF (DMF, 3:1 THF:DMF or toluene) (10 mL) with
stirring under argon gas at ambient temperature (ca. 20 °C).
The deep violet, blue, or red solution was stirred for 5 min,
and an acetone solution of DMD (ca. 2.5 mmol, 42 mL of ca.
0.06 M) was added to the mixture in one portion. The color
changed to bright yellow. After 5 min of further stirring,
saturated aqueous NH4Cl (0.2 mL) was added, and the solution
was dried over anhydrous MgSO4. The solid phase was
removed by filtration and washed with acetone (20 mL). The
solvents were evaporated (25 °C, 15 Torr), and the residue was
dissolved in 20 mL of methylene chloride, and passed through
a short silica gel column (ca. 5 g). After evaporation of the
solvent (25 °C, 15 Torr), the products were purified by
preparative TLC with hexane/ethyl acetate (20:1) as the
eluent. The solid products were additionally recrystallized.
p-Nitr oben za ld eh yd e9 (3a ): 91.0 mg (60%) of yellow
powder; mp 102-103 °C (EtOH).
(m, 11H), 6.91 (dd, 1H, J ) 8.5, J ) 1.7), 3.89 (s, 3H), 3.19 (s
broad, 1H). Anal. Calcd for C20H17NO4: C, 71.63; H, 5.11; N,
4.18. Found: C, 71.53; H, 5.08; N, 3.95.
4-Be n zh yd r ylid e n e -2-ch lor ocycloh e xa -2,5-d ie n on e
(5e): 158 mg (54%) of an orange oil. 1H NMR (200 MHz,
CDCl3) δ ) 7.40-7.20 (m, 11H), 7.05 (dd, 1H, J ) 8.6, J )
2.2), 6.93 (d, 1H, J ) 8.5). EIMS(+) HR: calcd for C19H1335ClO
(M)+•: 292.06549; found: 292.06768.
(3-Ch lor o-4-n itr op h en yl)d ip h en ylca r bin ol (6e): 96.0
1
mg (28%) of a yellow oil. H NMR (200 MHz, CDCl3) δ ) 7.80
(d, 1H, J ) 8.5), 7.64 (d, 1H, J ) 1.9), 7.39-7.31 (m, 7H), 7.28-
7.20 (m, 4H), 2.94 (s, 1H). Anal. Calcd for C19H14NO3Cl: C,
67.16; H, 4.15; N, 4.12. Found: C, 67.12; H, 4.45; N, 4.01.
4-Ben zh yd r ylid en e-3-m et h oxycycloh exa -2,5-d ien on e
(5f): 127 mg (44%) of orange needles; mp 109-110 °C
1
(cyclohexane/CH2Cl2). H NMR (200 MHz, CDCl3) δ ) 7.52-
7.10 (m, 10H), 6.51 (d, 1H, J ) 2.2), 6.30 (s, 1H), 6.27 (d, 1H,
J ) 2.2), 3.62 (s, 3H). EIMS(+) HR: calcd for C20H16O2 (M)+•
288.11503; found: 288.11483.
:
(2-Meth oxy-4-n itr op h en yl)d ip h en ylca r bin ol (6f): 44.0
1
p-Nitr oa cetop h en on e9 (3b): 55.0 mg (33%) of colorless
powder; mp 80-81 °C (EtOH).
mg (13%) of a yellow oil. H NMR (200 MHz, CDCl3) δ ) 7.80
(d, 1H, J ) 2.2), 7.71 (dd, 1H, J ) 8.5, J ) 2.2), 7.35-7.27 (m,
6H), 7.26-7.17 (m, 4H), 6.74 (d, 1H, J ) 8.5), 3.84 (s, 1H),
3.77 (s, 3H). Anal. Calcd for C20H17NO4: C, 71.63; H, 5.11; N,
4.18. Found: C, 71.63; H, 4.97; N, 4.04.
1-Nitr on a p h th a len e-2-ca r ba ld eh yd e14 (3c): 61.0 mg
(30%) of colorless powder; mp 95-96 °C (EtOH).
2-Nitr o-5-ch lor oben za ld eh yd e14 (3d ): 80.0 mg (43%) of
colorless needles; mp 75-76 °C (EtOH).
1,1-Dip h en yl-1-(2-m eth oxy-4-n itr op h en yl)eth a n e (7f):
1
2-(4-Nitr op h en yl)-p r op a n -2-ol15 (2e): 154 mg (85%) of an
orange oil. 1H NMR (200 MHz, CDCl3) δ ) 8.13-8.22 (m, 2H),
7.62-7.70 (m, 2H), 2.18 (s br. 1H), 1.62 (s, 6H). Anal. Calcd
for C9H11NO3: C, 59.66; H, 6.12; N, 7.73. Found: C, 59.28; H,
6.49; N, 7.31.
100 mg (30%) of colorless cubes; mp 105-106 °C (EtOH). H
NMR (200 MHz, CDCl3) δ ) 7.65-7.80 (m, 2H), 7.38-7.19 (m,
6H), 7.13-7.03 (m, 4H), 6.88 (d, 1H, J ) 8.8), 3.56 (s, 3H),
2.25 (s, 3H). Anal. Calcd for C21H19NO3: C, 75.66; H, 5.74; N,
4.20. Found: C, 75.53; H, 5.79; N, 4.12.
4-Ben zh ydr yliden e-3-ch lor ocycloh exa-2,5-dien on e (5g):
Meth yl r-h yd r oxy-r-(4-n itr op h en yl)-r-p h en yla ceta te
(2f): 181 mg (63%) of an orange oil; 1H NMR (200 MHz, CDCl3)
δ )8.15-8.25 (m, 2H), 7.72-7.83 (m, 2H), 7.38-7.33 (m, 5H),
4.38 (s broad, 1H), 3.89 (s, 3H). Anal. Calcd for C15H13NO5:
C, 62.72; H, 4.56; N, 4.88. Found: C, 62.79; H, 4.49; N, 4.84.
9-(4-Nitr op h en yl)-9H-flu or en -9-ol16 (2g): 300 mg (99%)
of yellow cubes; mp 160-161 °C (EtOH).
1
150 mg (51%) of an orange oil. H NMR (200 MHz, CDCl3) δ
) 7.37-7.21 (m, 10H), 6.91 (dd, 1H, J ) 2.0, J ) 0.9), 6.54 (d,
1H, J ) 2.0), 6.53 (s, 1H). EIMS(+) HR: calcd for C19H13O35Cl
(M)+• 292.06549; found: 292.06599.
(2-Ch lor o-4-n itr op h en yl)d ip h en ylca r bin ol (6g): 28.0
1
mg (8%) of a yellow oil. H NMR (200 MHz, CDCl3) δ ) 8.27
(d, 1H, J ) 2.3), 7.97 (dd, 1H, J ) 8.7, J ) 2.4), 7.41-7.20 (m,
4-Ben zh yd r ylid en ecycloh exa -2,5-d ien on e17 (5a ): 127
mg (49%) of orange cubes; mp 165-166 °C (benzene).
(4-Nitr op h en yl)d ip h en ylca r bin ol18 (6a ): 83.0 mg (27%)
of colorless cubes; mp 96-97 °C (cyclohexane).
10H), 7.03 (d, 1H, J ) 8.7), 4.21 (s, 1H). Anal. Calcd for C19H14
-
ClNO2: C, 67.16; H, 4.15; N, 4.12. Found: C, 67.12; H, 4.00;
N, 3.99.
4-Be n zh yd r ylid e n e -3-cya n ocycloh e xa -2,5-d ie n on e
(5h ): 182 mg (64%) of an orange powder; mp 112-113 °C
(cyclohexane/CH2Cl2). 1H NMR (200 MHz, CDCl3) δ ) 8.95 (d,
1H, J ) 2.2), 8.35 (dd, 1H, J ) 8.4, J ) 2.2), 7.40-6.60 (m,
10H), 6.33 (d, 1H, J ) 8.5). EIMS(+) HR: calcd for C20H13ON
(M)+•: 283.09971; found: 283.09910.
1,1-Dip h en yl-1-(4-n itr op h en yl)eth a n e (7a ): 52.0 mg
1
(17%) of colorless cubes; mp 97-98 °C (EtOH). H NMR (200
MHz, CDCl3) δ ) 8.10-8.19 (m, 2H), 7.42-7.28 (m, 8H), 7.18-
7.08 (m, 4H), 2.27 (s, 3H). Anal. Calcd for C20H17NO2: C, 79.19;
H, 5.65; N, 4.62. Found: C, 79.18; H, 5.47; N, 4.51.
4-Ben zh yd r ylid en e-4a ,8a -d ih yd r o-4H -n a p h t h a len -1-
on e19 (5b): 281 mg (91%) of an orange powder; mp 185-186
°C (benzene).
4-[(4-Ch lor o-p h e n yl)p h e n ylm e t h yle n e ]-3-m e t h oxy-
cycloh exa -2,5-d ien on e (5i): 130 mg (40%) of an orange oil.
1H NMR (200 MHz, CDCl3) δ ) 7.12-7.33 (m, 9H), 6.47 (d,
1H, J ) 2.1), 6.27 (s, 1H), 6.25 (d, 1H, J ) 2.2), 3.61 (s, 3H).
4-B e n zh y d r y lid e n e -2-io d o c y c lo h e x a -2,5-d ie n o n e
(5c): 120 mg (31%) of an orange oil. 1H NMR (200 MHz,
CDCl3) δ ) 7.55-7.20 (m, 10H), 7.08 (dd, 1H, J ) 8.5, J )
2.2), 6.90 (d, 1H, J ) 8.6), 6.58 (d, 1H, J ) 2.2). EIMS(+) HR:
calcd for C19H13OI (M)+• 384.00112; found: 384.00217.
(3-Iod o-4-n itr op h en yl)d ip h en yl ca r bin ol (6c): 156.0 mg
EIMS(+) HR: calcd for
found: 322.07676.
C : 322.07606;
20H15O235Cl (M)+•
(4-Ch lor op h en yl)-(2-m eth oxy-4-n itr op h en yl)p h en yl-
1
ca r bin ol (6i): 97.0 mg (26%) of an orange oil. H NMR (200
MHz, CDCl3) δ ) 7.81 (d, 1H, J ) 2.2), 7.72 (dd, 1H, J ) 8.5,
J ) 2.2), 7.10-7.37 (m, 9H), 6.73 (d,1H, J ) 8.5), 4.99 (s, 1H),
3.80 (s, 3H). Anal. Calcd for C20H16NO4Cl: C, 64.96; H, 4.36;
N, 3.79. Found: C, 65.09; H, 4.20; N, 3.63.
1-(4-Ch lor op h e n yl)-1-(2-m e t h oxy-4-n it r op h e n yl)-1-
p h en yleth a n e (7i): 122 mg (33%) of a yellow oil. 1H NMR
(200 MHz, CDCl3) δ ) 7.66-7.72 (m, 2H), 7.18-7.35 (m, 5H),
6.97-7.08 (m, 4H), 6.88 (d, 1H, J ) 9.0), 3.60 (s, 3H), 2.22 (s,
3H). Anal. Calcd for C21H18NO3Cl: C, 68.57; H, 4.93; N, 3.81.
Found: C, 68.17; H, 4.62; N, 3.46.
1
(36%) of a yellow oil. H NMR (200 MHz, CDCl3) δ ) 8.15 (d,
1H, J ) 1.9), 7.76 (d, 1H, J ) 8.5), 7.42-7.19 (m, 11H), 2.90
(s, 1H). Anal. Calcd for C19H14NO3I: C, 52.92; H, 3.27; N, 3.25.
Found: C, 52.94; H, 3.29; N, 3.11.
4-B e n z h y d r y li d e n e -2-m e t h o x y c y c lo h e x a -2,5-d i -
en on e17 (5d ): 144 mg (50%) of orange plates; mp 185-186
°C (benzene).
(3-Meth oxy-4-n itr op h en yl)d ip h en ylca r bin ol (6d ): 104
mg (31%) of colorless cubes; mp 133-135 °C (cyclohexane). 1H
NMR (200 MHz, CDCl3) δ ) 7.80 (d, 1H, J ) 8.4), 7.45-7.23
4-(Na p h t h a len -1-yl-p h en ylm et h ylen e)cycloh exa -2,5-
d ien on e (5j): 186 mg (60%) of an orange powder; mp 168-
1
170 °C (cyclohexane/CH2Cl2). H NMR (500 MHz, CDCl3) δ )
(14) Ma¸kosza, M.; Owczarczyk, Z. J . Org. Chem. 1989, 54, 5094.
(15) Kornblum, N.; Ackermann, P. S.; Swiger, R. T. J . Org. Chem.
1980, 45, 5294.
(16) Von Wittig, G.; Doser, H.; Lorenz, I. Liebigs Ann. Chem. 1949,
192.
(17) Ioffe, I. S.; Chawin, Z. J . Zh. Obsch. Khim. 1949, 19, 917.
(18) Starnes, W. H. J . Am. Chem. Soc. 1968, 90, 1807.
(19) Gomberg, M.; Sullivan, F. W. J . Am. Chem. Soc. 1920, 42, 1867.
7.95 (d, 1H, J ) 8.3), 7.90 (d, 1H, J ) 8.2), 7.65 (dd, 1H, J )
10.1, J ) 2.7), 7.61 (d, 1H, J ) 8.5), 7.54 (t, 1H, J ) 7.7), 7.45
(t, 1H, J ) 7.5), 7.32-7.42 (m, 7H), 6.98 (dd, 1H, J ) 10.0, J
) 2.7), 6.53 (dd, 1H, J ) 10.1, J ) 2.0), 6.28 (dd, 1H, J ) 10.0,
J ) 2.1). Anal. Calcd for C23H16O: C, 89.58; H, 5.23. Found:
C, 89.36; H, 4.98.

5026 J . Org. Chem., Vol. 66, No. 15, 2001
Adam et al.
n
(4-Nitr op h en yl)-(1-n a p h th yl)p h en ylca r bin ol (6j): 57.0
mg (16%) of a colorless powder; mp 150-151 °C (cyclohexane/
The nBu4N+ salt was prepared analogously with Bu4N+OH-
solution in dioxane as base.
1
CH2Cl2). H NMR (500 MHz, CDCl3) δ ) 8.11-8.15 (m, 2H),
7.95 (d, 1H, J ) 8.6), 7.81-7.87 (m, 2H), 7.49-7.53 (m, 2H),
7.38-7.43 (m, 1H), 7.22-7.36 (m, 7H), 6.84 (dd, 1H, J ) 7.3,
J ) 1.0), 3.58 (s, 1H). Anal. Calcd for C23H17NO3: C, 77.73; H,
4.82; N, 3.94. Found: C, 77.41; H, 4.87; N, 3.66.
Ack n ow led gm en t. The work in Warsaw was gener-
ously suported by the State Committee for Scientific
Research (grant no. PBZ 6. 01), the work in Wu¨rzburg
by the Deutsche Forschungsgemeinschaft (Schwerpunk-
tprogramm “Peroxidchemie”) and the Founds der Che-
mischen Industrie. This cooperative project was initi-
ated during the stay of M. Ma¸kosza in Wu¨rzburg as an
Alexander-von-Humboldt Awardee. C.-G. Zhao thanks
the Deutsche Akademische Austauschdienst (DAAD) for
a doctoral fellowship.
Oxid a tion of Nitr oben zylic Sa lts (Excep t th e P ota s-
siu m Sa lt) by DMD. The nitroarene 4a (1.0 mmol, 289 mg)
was added to a solution of t-BuOK (2.0 mmol, 224 mg) in dry
THF (10 mL) while stirring under argon gas at ambient
temperature (ca. 20 °C). The deep red solution was stirred for
another 5 min, the appropriate salt was added (LiCl or MgCl2,
5 mmol), and the solution was stirred for 15 min. Then an
acetone solution of DMD (ca. 2.5 mmol, 42 mL of ca. 0.06 M)
was added to the mixture in one portion, and the color changed
to yellow. After 5 min of further stirring, saturated aqueous
NH4Cl (1 mL) was added, and the workup was conducted as
described in the preceding procedure.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectral
and elemental analyses data. This material is available free
of charge via the Internet at http://pubs.acs.org.
The sodium salt was prepared analogously with t-BuONa
as base.
J O010055Z