Notes
J . Org. Chem., Vol. 63, No. 21, 1998 7535
In conclusion, the above-mentioned results indicate
that the π-conjugate molecules possessing a reversible
redox function contribute to the construction of an
efficient organic and complex catalytic system under
oxygen.
Exp er im en ta l Section
Syn th esis of 1 a n d 4. The preparation of 1a , 1c, 4a , and
4c was carried out according to the reported method.3 4d was
prepared as follows. To a solution of 4a (290 mg, 1.00 mmol) in
DMF (25 mL) was added dropwise a solution of acryloyl chloride
(181 mg, 2.00 mmol) and pyridine (313 mg, 4.00 mmol) in DMF
(5 mL) at 0 °C under argon. Stirring was continued for an
additional 5 h. The reaction mixture was concentrated under
reduced pressure. Methanol (20 mL) was added to the obtained
residue, which was filtered to remove the insoluble black solid.
Reprecipitation of the concentrated filtrate from a saturated
aqueous solution of NaHCO3 was carried out three times.
Further reprecipitation from hexane (200 mL) gave 235 mg (59%
yield) of 4d . mp 213-214 °C (uncorrected, dec); IR (KBr) 3300,
1659, 1613, 1510, 1384, 1307, 822 cm-1 1H NMR (600 MHz,
;
DMSO-d6) δ 9.91 (s, 2H), 7.80 (s, 2H), 7.48 (dd, 4H, J ) 7.2, 1.8
Hz), 6.98 (s, 4H), 6.92 (dd, 4H, J ) 7.2, 1.8 Hz), 6.40 (dd, 2H, J
) 17.1, 10.5 Hz), 6.20 (dd, 2H, J ) 17.1, 2.1 Hz), 5.69 (dd, 2H,
J ) 10.5, 2.1 Hz); MS (FAB) m/z, 398 (M+). Anal. Calcd for
C24H22N4O2‚1.25H2O: C, 68.47; H, 5.87; N, 13.31. Found: C,
68.20; H, 5.41; N, 13.66.
F igu r e 1. UV-vis spectra. (a) [1a ] ) 5.0 × 10-5 M; solvent
MeCN. (b) (1) treatment with benzylamine at 70 °C for 5 h
under argon; (2) treatment at room temperature for 9 h under
atmospheric oxygen.
Polymerization was carried out by treatment of 4d (40 mg,
0.10 mmol) in dichloromethane with benzoyl peroxide (2.4 mg,
0.01 mmol) at 80 °C for 24 h under argon in a sealed glass tube.
The blue solid polymer (28 mg) was washed with dichlo-
romethane and methanol and dried; mp >300 °C; IR (KBr) 3313,
absorption around 540 nm in the UV-vis spectrum of
1a (Figure 1a), which is possibly assigned to the CT band
between the benzenoid and quinoid moieties, disappeared
on treatment with benzylamine at 70 °C under argon.
This spectral change implies the reduction of 1a to 4a .
The absorption reappeared to some extent upon contact
with atmospheric oxygen (Figure 1b). The phenylenedi-
1658, 1603, 1536, 1503, 1319, 1250, 823 cm-1
. Anal. Found:
C
24H22.46N4.15
.
A Rep r esen ta tive P r oced u r e for th e Ca ta lytic Oxid a -
tion of 2,6-Di-ter t-bu tylp h en ol. A mixture of 2,6-di-tert-
butylphenol (206 mg, 1.00 mmol) and 1a (29 mg, 0.10 mmol) in
DMF (1 mL) was stirred at 70 °C for 40 h under atmospheric
oxygen. Ether (50 mL) was added to the reaction mixture, which
was filtered and concentrated. The yields of 2 and 3 were
determined by GLC as shown in Table 1.2
1
amine 4a was also detected by H NMR in the reaction
mixture obtained similarly in acetonitrile-d3. These
results support the catalytic cycle of 1 or 4 shown in
Scheme 1.
A Rep r esen ta tive P r oced u r e for th e Ca ta lytic Oxid a -
tion of Ben zyla m in e. A mixture of benzylamine (107 mg, 1.00
mmol) and 1a (29 mg, 0.10 mmol) in acetonitrile (1 mL) was
stirred at reflux for 24 h under atmospheric oxygen. Ether (50
mL) was added to the reaction mixture, which was filtered and
concentrated. The yield of N-benzylidenebenzylamine was
determined by GLC as shown in eq 2.2
A Rep r esen ta tive P r oced u r e for th e Ca ta lytic Oxid a -
tion of Ben zyl Alcoh ol. To a mixture of 1a (29 mg, 0.10 mmol),
copper(I) chloride (9.9 mg, 0.10 mmol), and potassium carbonate
(553 mg, 4.00 mmol) in toluene (2 mL) was added benzyl alcohol
(216 mg, 2.00 mmol). The mixture was stirred at 90 °C for 24
h under atmospheric oxygen. Ether (50 mL) was added to the
reaction mixture, which was filtered and concentrated. The yield
of benzaldehyde was determined by GLC as shown in eq 3.
Benzoic acid was not detected by GLC.
Sch em e 1
The combination of polyanilines and a copper or iron
salt is revealed to form an efficient complex catalytic
system,2 and the imine moiety of 1c is capable of
coordinating to transition metals.6 Benzyl alcohol was
allowed to undergo the dehydrogenation to benzaldehyde
on treatment with a catalytic amount of copper(I) chloride
and 1a or 1c in the presence of potassium carbonate (eq
3). Both catalytic components are essential for the
Mea su r em en t of UV-Vis a n d 1H NMR Sp ectr a in th e
Red ox P r ocess of 1a . The oxidation reaction of benzylamine
was carried out similarly as mentioned above at 70 °C for 5 h
under argon. The obtained solution was diluted to ca. 5 × 10-5
M with acetonitrile for the measurement of the UV-vis spec-
trum. The solution was contacted with atmospheric oxygen at
room temperature for 9 h to give the spectrum shown in Figure
1
1. For the measurement of the H NMR spectrum, acetonitrile-
d3 was used as a solvent.
effective conversion. Since the azodicarboxylate has been
reported to serve as a hydrogen acceptor,7 1 might also
play a similar role in the present oxidative transforma-
tion.
J O980884T
(7) Marko´, I. E.; Giles, P. R.; Tsukazaki, M.; Brown, S. M.; Urch, C.
J . Science 1996, 274, 2044; Angew. Chem., Int. Ed. Engl. 1997, 36,
2208.
(6) Moriuchi, T.; Bandoh, S.; Miyaishi, M.; Hirao, T., to be published.