Oxyfunctionalization of biphenylene by singlet oxygen, hydrogen peroxide/methyltrioxorhenium, and dimethyldioxirane

Full text of DOI:10.1021/jo972308n

8
544
J . Org. Chem. 1998, 63, 8544-8546
Notes
Oxyfu n ction a liza tion of Bip h en ylen e by
Sch em e 1
Sin glet Oxygen , Hyd r ogen P er oxid e/
Meth yltr ioxor h en iu m , a n d
Dim eth yld ioxir a n e
†
‡
,†,§
Waldemar Adam, Metin Balci, and Hamdullah Kili c¸ *
Institut f u¨ r Organische Chemie, Universit a¨ t W u¨ rzburg,
Am Hubland, D-97074 W u¨ rzburg, Germany, Department of
Chemistry, Middle East Technical University,
Ankara, Turkey, and Department of Chemistry,
Atat u¨ rk University, 25240 Erzurum, Turkey
Received December 23, 1997
In tr od u ction
Cyclobutadiene (1), the smallest annulene, has con-
tinued to attract the interest of both experimental and
theoretical chemists.1 The cyclobutadiene unit may be
stabilized by incorporating one or both of the double
lenes are well-known, biphenylene endoperoxide 4, formed
by the [4 + 2]cycloaddition of singlet oxygen, has as yet
not been reported. Biphenylene (3) is known to be inert
to autoxidation but may be oxidized under forcing condi-
tions to phthalic acid and to a number of unidentified
2
bonds into a benzene ring, as in benzocyclobutadiene (2)
3
and biphenylene (3), the mono- and dibenzo derivatives
of cyclobutadiene.
6
7
products on treatment with osmium tetraoxide or ozone.
Low yields of 2,3-biphenylenequinone (12) and several
homolytic substitution products have been obtained by
8
the reaction of 3 with either ceric ammonium nitrate,
9
10
lead tetraacetate, or manganese(III) acetate.
In this paper, we have examined the oxidation of
biphenylene (3) by singlet oxygen, H activated with
methyltrioxorhenium (MTO) as catalyst, and dimeth-
yldioxirane (DMD).12 Our results show that unusual
oxidation processes have been observed with these three
oxidants.
Both derivatives 2 and 3 have an overall 4n π-electron
and might, therefore, be expected to show antiaromatic
behavior. This holds for benzocyclobutadiene (2), which
is observed only as a reactive intermediate. In contrast,
biphenylene (3) is thermally stable and shows many of
the properties associated with aromatic compounds.
Thus, biphenylene (3) preferentially undergoes substitu-
tion rather than addition reactions, and it does not
readily participate in Diels-Alder cycloadditions. It
forms charge-transfer complexes with maleic anhydride
and tetracyanoethylene; the latter does not give cycload-
2
O
2
1
1
Resu lts a n d Discu ssion
Sin glet Oxygen . Tetraphenylporphine-sensitized pho-
tooxygenation of arene 3 in acetone resulted in the
hemiketal hydroperoxide 5 (Scheme 1). After chroma-
tography on silica gel, 5 was isolated as the sole product
in 56% yield. The structural assignment of the hydro-
peroxide 5 rests on its physical and chemical behavior.
ducts even on heating.2
b,4
However, 3 reacts with the
more electron-deficient dienophile tetrachloro(fluoro)-
benzyne but not with benzyne.5
While the endoperoxides of polycyclic aromatic com-
pounds such as anthracenes and substituted naphtha-
†
W u¨ rzburg University.
Middle East Technical University.
Atat u¨ rk University.
(6) Barton, J . W. Non Benzenoid Aromatics; Academic Press: New
York, 1969; Vol. 1, p 32.
(7) Baker, W.; Boarland, M. P. V.; McOmie, J . F. W. J . Chem. Soc.
1954, 1476-1482.
(8) (a) Sato, M.; Fujino, H.; Ebine, S.; Tsunetsuga, J . Bull. Chem.
Soc. J pn. 1977, 50, 3076. (b) Blatchly, J . M.; McOmie, J . F. W.; Thatte,
S. D. J . Chem. Soc. 1962, 5090-5095 (c) For the synthesis of the
isomeric biphenylene-p-quinone see: Kili c¸ , H., Balci, M.; Yurtsever,
E. J . Org. Chem. 1997, 62, 3434-3435.
(9) Kurosawa, K.; Takemura, T.; Ueno, Y.; McOmie, J . F. M.;
Pearson, N. D. Bull. Chem. Soc. J pn. 1984, 57, 1914-1919.
(10) Kurosawa, K.; McOmie, J . F. M. Bull. Chem. Soc. J pn. 1981,
54, 3877-3878.
(11) Herrmann, W. A.; K u¨ hn, F. E. Acc. Chem. Res. 1997, 30, 169-
180.
‡
§
(
1) (a) Bally, T.; Masamune, S. Tetrahedron 1980, 36, 343-370. (b)
Maier, G. Angew. Chem., Int. Ed. Engl. 1988, 27, 309.
2) (a) Cava, M. P.; Mitchell, M. J . Cyclobutadiene and Related
(
Compounds; Academic Press: New York, 1967. (b) Baker, W.; McOmie,
J . F. W. Cyclobutadiene and Related Compounds in Nonbenzenoid
Aromatic Compounds; Ginsburg, D., Ed., Interscience: New York,
1
959.
(3) (a) Cava, M. P.; Stucker, M. P. J . Am. Chem. Soc. 1957, 79,
1
706-1709. (b) Shepherd, M. K. Cyclobutarenes: The Chemistry of
Benzocyclobutene, Biphenylene and Related Compounds; Elsevier:
Amsterdam, 1991.
(
4) Heany, H.; Mason, K. G.; Scetchley, J . M. Tetrahedron Lett. 1970,
85-488.
5) Heaney, H.; Lees, P. Tetrahedron Lett. 1964, 3049-3052.
4
(12) Adam, W.; Schmerz, A. K. Bull. Soc. Chim. Belg. 1996, 105,
581-599.
(
1
0.1021/jo972308n CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/27/1998

Notes
J . Org. Chem., Vol. 63, No. 23, 1998 8545
Sch em e 2
Sch em e 3
of maleic anhydride to biphenylene.14 Furthermore, on
warming to ca. 10 °C, the endoperoxide 4 underwent a
retro-Diels-Alder reaction to give singlet oxygen and
biphenylene. The ease of such molecular oxygen extru-
sion from polycyclic arenes depends on the nature of the
1
5
aromatic system and on the type of substituents and is
favorable for the present.16
In competition with the retro-Diels-Alder reactions,
endoperoxide 4 suffers electrocyclic fragmentation to the
dicarbonyl product 8 (Scheme 2). The latter intermediate
intramolecularly subsequently cyclizes to the correspond-
ing furanol derivative 9, which will be in equilibrium
with its tautomeric 2(3H)-furanone 10; additionally, 10
may be generated directly from 8 (Scheme 2). Ene
reaction17 of furanone 10 with singlet oxygen should
finally lead to the observed hydroperoxide 5 as isolable
product.
Thus, the elemental analysis confirmed the molecular
1
3
formula C12
H
8
O
4
,
while the lactone structure was
1
13
established by its 250 MHz H NMR, 63 MHz C NMR,
and IR spectra. The olefinic hydrogens display an AB-
system at 8.12 and 6.37 ppm (J ) 5.6 Hz) as required by
the R,â-unsaturated carbonyl derivatives. Aromatic pro-
tons comprise a multiplet, and the singlet at 4.03 ppm
belongs to the acetylenic proton with a large (252 Hz)
J
CH coupling, as expected for acetylenic compounds. The
hydroperoxide and lactone functional groups are indi-
cated by the IR-spectral absorptions at 3276 and 1748
Hyd r ogen P er oxid e/Meth yltr ioxor h en iu m (MTO).
The oxidation of biphenylene (3) by hydrogen peroxide
with a catalytic amount of methyltrioxorhenium (CH3-
-
1
13
2
cm
.
The C NMR spectrum consisting of nine sp
3
carbon and two sp and one sp carbon signals is in accord
with the proposed structure.
ReO ) in chloroform afforded the o-quinone 12 in 83%
3
yield (20% conversion of 3) at room temperature (Scheme
To corroborate the structure chemically, hydroperoxide
was allowed to react with aqueous sodium bisulfite to
3). All observed spectral data were consistent with the
5
reported ones.8
afford the trans keto acid 6. The olefinic protons display
an AB system, and its large coupling constant (J ) 15.6
Hz) clearly shows the trans configuration of the double
bond in the cinnamic acid derivatives 6. Furthermore,
the 13C NMR spectrum indicates the presence of two
carbonyl groups (191.7 and 170.7 ppm), which again
supports the assigned structure.
The formation of quinone 12 is rationalized in terms
of the reaction path shown in Scheme 3. Epoxidation of
the 2,3 bond in biphenylene leads first to the monoep-
oxide 11;18 the latter does not rearrange to the corre-
sponding oxepin derivative due to its cyclobutadienic
character.19 Acid-catalyzed epoxide-ring opening, fol-
lowed by oxidation of the diol with H O /MTO, presum-
2
2
To elucidate the mechanistic details of this unusual
process, the photooxygenation was conducted at -40 °C
ably results finally in the o-quinone 12.
Dim eth yld ioxir a n e (DMD). With dimethyldioxirane
(DMD), a powerful oxidant under neutral conditions,
after 1 day of oxidation, the biphenylene (3) was con-
verted exclusively to the trisepoxide 13 to the extent
1
and monitored by H NMR spectroscopy. The observed
NMR data provide evidence for the bicyclic endoperoxide
1
4
, proposed to be formed in the initial step of this O
2
1
reaction (Scheme 2). Thus, the observed AB system for
the olefinic protons at 6.9-7.15 ppm (low-field part is
further split by the bridgehead protons), the doublet at
of only 30%, as observed by H NMR spectroscopy
1
(Scheme 4). The H NMR spectrum of the trisepoxide
13 displayed an AA′BB′ system, which was assigned to
6
.6 ppm (other olefinic proton), and the triplet at 5.9 ppm
(
bridgehead proton) substantiate the structure of endop-
(
14) Roberts, J . D. Molecular Orbital Calculations; Benjamin: New
eroxide 4.
York, 1962.
(
(
15) Balci, M. Chem. Rev. 1981, 81, 91-108.
16) Attempts to reduce the endoperoxide 4 in situ by thiourea to
As is evident, cycloaddition has taken place across the
C-2/C-4a positions in biphenylene (3), which corroborates
the theoretical product stabilities for the cycloaddition
the corresponding diol failed because the photooxidation of thiourea
was much faster than that of biphenylene.
(
17) Prein, M.; Adam, W. Angew. Chem., Int. Ed. Engl. 1996, 35,
4
77-494.
(13) A similar transformation was reported for the photooxygenation
(18) Adam, W.; Herrmann, W. A.; Lin, J .; Saha-M o¨ ller, C. R.;
of 2,3,7,8-tetrakis(trimethylsilyl)benzo[3,4]cyclobuta[1,2-b]biphenyl-
ene: Mestdagh, H.; Vollhardt, K. P. C. J . Chem. Soc., Chem. Commun.
Fischer, R. W.; Correia, J . D. G. Angew. Chem., Int. Ed. Engl. 1994,
33, 2475-2477.
(19) J ikeli, G.; G u¨ nther, H. Angew. Chem. 1974, 86, 278-279.
1
986, 281-282.

8
546 J . Org. Chem., Vol. 63, No. 23, 1998
Notes
82.1; IR (KBr, cm-1) 3276, 3117, 2913, 2851, 1748, 1469, 1433,
Sch em e 4
1
6
337, 1243, 1123, 1075, 935.5. Anal. Calcd for C12
6.69; H, 3.70. Found: C, 66.33; H, 3.66.
8 4
H O : C,
3
-(2-Eth yn ylben zoyl)a cr ylic Acid (6). To a stirred solution
of 140 mg (0.64 mmol) of hydroperoxide 5 in 15 mL of dichlo-
romethane was added 2 mL of saturated sodium bisulfite
solution at room temperature (ca. 20 °C). The resulting mixture
was stirred for 5 min, while the reaction progress was monitored
by means of the peroxide test (KI/HOAc). The mixture was
extracted with dichloromethane (2 × 50 mL) and dried over
magnesium sulfate. The solvent was removed under reduced
pressure ca. 20 °C at 15 Torr to afford a light yellow solid (77
mg; 60%): mp 100 °C from dichloromethane-carbon tetrachlo-
1
ride; H NMR (250 MHz, CDCl
1
)
3
) δ 10.00 (bs, 1H,), 7.92 (d, J )
5.6 Hz, 1H), 7.70-7.61 (m, 2H), 7.56-7.43 (m, 2H), 6.75 (d, J
15.6 Hz, 1H), 3.41 (s, 1H); 13C NMR (63 MHz, CDCI
) δ 191.7,
3
1
8
1
70.7, 141.0, 140.9, 134.5, 132.1, 130.9, 129.1, 129.0 121.0, 84.4,
1.5; IR (KBr, cm ) 3295.3, 3013, 2684, 1701, 1672, 1590, 1437,
413, 1307, 1278, 1190, 1014, 920, 749. Anal. Calcd for
-1
C
12
H
8
O
3
: C, 72.02; H, 3.99. Found: C, 71.89; H, 3.83.
2
,3-Bip h en ylen equ in on e (12). To a magnetically stirred
solution of 350 mg (2.3 mmol) of biphenylene in 20 mL of
chloroform were added 12 mg (0.05 mmol) of methyltrioxo-
rhenium, 150 mg (2.5 mmol) of glacial acetic acid, and 0.2 mL
the symmetrical benzo group. The epoxide protons
appear as two separate singlets at 3.98 and 3.48 ppm,
2 2
(5 mmol) of H O (85%) at room temperature. The mixture was
as expected for the trans configuration of the epoxide
rings.20
stirred at room temperature for ca. 20 °C for 5 h and extracted
with chloroform (2 × 20 mL). The combined extracts were
washed with water and dried over magnesium sulfate. The
solvent was evaporated at ca. 20 °C and 15 Torr, and the residue
was submitted to silica gel (50 g) chromatograph with hexanes-
EtOAc as eluent to afford 280 mg of unreacted biphenylene (3)
These three oxidations show unequivocally that bi-
phenylene (3) may be oxyfunctionalized under relatively
mild conditions.
and 60.0 mg (0.32 mmol; 83%) of a red-orange solid, mp 210-
Exp er im en ta l Section
1
2
12 °C identified as 2,3-biphenylenequinone (12): H NMR (250
) δ 7.72 (s, 4H), 6.62 (s, 2H); 13C NMR (63 MHz,
3
1
Biphenylene was synthesized according to the literature.21
MHz, CDCI
CDCI ) δ 179.5, 156.5, 147.8, 135.2, 124.1, 115.9; IR (KBr, cm
076, 1642, 1560, 1299, 1243, 1220, 1077, 857.
Dim eth yld ioxir a n e Ep oxid a tion of Bip h en ylen e to th e
Tr isep oxid e 13. To a magnetically stirred solution of 5 mL
ca. 0.39 mmol) of dimethyldioxirane (DMD) in acetone was
-
)
Reagents and solvents were purchased from standard chemical
suppliers and purified to match the reported physical and
spectral data. Acetone was stored over 4 Å molecular sieves
before use. Melting points were taken on a B u¨ chi apparatus.
Solvents were concentrated at reduced pressure (ca. 20 °C, 20
Torr). Infrared spectra were obtained on KBr pellets by employ-
3
3
(
added 40.0 mg (0.260 mmol) of biphenylene (3), and the resulting
mixture was stirred at room temperature (ca. 20 °C) for 24 h,
while the reaction progress was monitored by means of the
peroxide test (KI/HOAc). After evaporation of the solvent at ca.
1
13
ing a Perkin-Elmer apparatus. H and C NMR spectra were
recorded on a 250 (63) MHz spectrometer. All column chroma-
tography was performed on silica gel.
2
0 °C and 15 Torr, the mixture was chromatographed on silica
5
-Hyd r op er oxy-5-(2-eth yn ylp h en yl)fu r a n -2-on e (5). A
sample of 1.0 g (6.57 mmol) of biphenylene and 50 mg of meso-
tetraphenylporphine in 25 mL of acetone were photolyzed for
d at -40 °C with a 400 W sodium lamp while oxygen gas was
bubbled through solution. After removal of the solvent, the
mixture was chromatographed over silica gel (40 g) by elution
with dichloromethane to afford 340 mg (2.23 mmol) of unreacted
biphenylene and TPP. Further elution with ethyl ether gave
gel (30 g) with hexane-EtOAc (4:1) as eluent to afford 25.0 mg
unreacted biphenylene (3) and 15.0 mg (97%) triepoxide 13 as
1
colorless solids: mp 205.2-205.8 °C from ether-hexane;
H
6
NMR (250 MHz, CDCI
3
) δ 7.50-7.72 (AA′BB′ system, 4H), 3.98
(
1
1
s, 2H), 3.48 (s, 2H); 13C NMR (63 MHz, CDCI
3
) δ 144.1, 131.4,
-
1
22.4, 68.24, 53.4, 52.9; IR (KBr, cm ) 3014, 1603, 1485, 1467,
361, 1324, 1287, 1163, 1135, 1089, 994, 956. Anal. Calcd for
12 8 3
C H O : C, 72.02; H, 3.99. Found: C, 71.75; H, 4.10.
5
30 mg (2.45 mmol) of hydroperoxide 5 in 56% yield (relative to
converted material, conversion. ca. 66%). Recrystallization from
dichloromethane afforded a colorless solid, which exploded above
Ack n ow led gm en t. This work was supported by the
1
1
20 °C without melting: H NMR (250 MHz, CD
3
COCD
3
) δ 11.82
Deutsche Forschungsgemeinschaft (SFB 347, “Selektive
Reaktionen metallautivierter Molek u¨ le”; Schwerpunk-
tprogramm, “Peroxidechemie: Mechanistische und pr a¨ -
parative Aspekte des Saurstoff-Transfers”) and Fond der
Chemischen. H.K. thanks the Technical and Scientific
Council of Turkey (TUBITAK) for a fellowship to
conduct this work in W u¨ rzburg. We are grateful to Ms.
Catherine Mitchell for a sample of MTO.
(
7
bs, 1H, hydroperoxide proton), 8.12 (d, J ) 5.6 Hz, 1H), 7.74-
.62 (m, 2H,), 7.53-7.48 (m, 2H), 6.37, (d, J ) 5.6 Hz, 1H), 4.03,
1
3
(
1
s, J CH ) 252.0 Hz, 1H); C NMR (63 MHz, CD
3
COCD
3
) δ 170.2,
52.5, 136.1, 135.7, 130.9, 130.1, 127.4, 124.2, 122.0, 112.2, 85.4,
(
20) (a) Vogel, E.; Altenbach, H. J .; Sommerfeld, C. D. Angew. Chem.
1
972, 84, 986-988. (b) Foster,. C. H.; Berchtold, G. A. B. J . Am. Chem.
Soc. 1972, 94, 7939.
21) Logullo, F. M.; Seitz, A. H.; Friedman, L. Org. Syntheses;
Wiley: New York, 1973; Collect. Vol. V, p 54.
(
J O972308N