E
Synlett
H. Komagawa et al.
Letter
M. S. Tetrahedron 2006, 62, 8227. (e) Matsumoto, T.; Ueno, M.;
Wang, N.; Kobayashi, S. Chem. Asian J. 2008, 3, 196. (f) Dohi, T.;
Kita, Y. Chem. Commun. 2009, 2073. (g) Mizuno, N.; Kamata, K.;
Yamaguchi, K. Top. Catal. 2010, 53, 876.
(18) In Togo’s catalyst system (see ref. 13), cyclic substrate like
1-tetralol does not undergo oxidation.
(19) We did not perform the reaction in more than 15-mmol scale.
(20) We have tried the oxidation of 1-hexadecanol (aliphatic
primary alcohol) under optimized condition. However no oxi-
dation took place, resulting in recovery of the starting material.
Oxidation of 3-undecanol (aliphatic secondary alcohol) under
optimized conditions proceeded sluggishly to afford the corre-
sponding ketone in 38% yield. Furthermore, oxidation of sub-
strates possessing alkenyl moiety such as 1-phenyl-5-hexen-1-
ol and cinnamyl alcohol did not proceed well probably due to
(
10) For the combination of stoichiometric amounts of alkali
bromide salts and oxidants for alcohol oxidation, see: (a) Koo,
B.-S.; Lee, C. K.; Lee, K.-J. Synth. Commun. 2002, 32, 2115.
(
(
b) Tesevic, V.; Gladysz, J. A. J. Org. Chem. 2006, 71, 7433.
c) Han, M.; Jeong, K. S.; Lee, J. C. Bull. Korean Chem. Soc. 2012,
33, 2405. (d) Pääkkönen, S.; Pursiainen, J.; Lajunen, M. Synth.
Commun. 2012, 42, 534.
+
(
11) Catalytic amounts of alkali bromide salts were frequently used
in TEMPO-based and related catalyst system. However, in these
the rapid consumption of catalytically active [Br ] species by
olefin.
–
+
catalyst systems, redox cycle between Br and [Br ] works for
re-oxidation of TEMPO to the corresponding oxoammonium
salt which is active species, see: (a) Rychnovsky, S. D.;
Vaidyanathan, R. J. Org. Chem. 1999, 64, 310. (b) Bolm, C.;
Magnus, A. S.; Hildebrand, J. P. Org. Lett. 2000, 2, 1173.
(21) Hoover, J. M.; Stahl, S. S. J. Am. Chem. Soc. 2011, 133, 16901.
(22) For a detail, see the Supporting Information.
(23) Yamaguchi, K.; Mizuno, N. Angew. Chem. Int. Ed. 2002, 41, 4538.
–
(24) Formation of Br from the reaction of Br with H O in the pres-
2
2
2
+
ence of H does not occur quantitatively because H O2 also
2
(
c) Tanaka, H.; Kawakami, Y.; Goto, K.; Kuroboshi, M. Tetrahe-
works as reducing agent toward Br according to the following
2
–
+
dron Lett. 2001, 42, 445. (d) Tanaka, H.; Kubota, J.; Itogawa, S.-I.;
Ido, T.; Kuroboshi, M.; Shimamura, K.; Uchida, T. Synlett 2003,
9
J. Org. Chem. 2003, 68, 4999. (f) Wu, X.-E.; Ma, L.; Ding, M.-X.;
Gao, L.-X. Synlett 2005, 607. (g) Shibuya, M.; Tomizawa, M.;
Suzuki, I.; Iwabuchi, Y. J. Am. Chem. Soc. 2006, 128, 8412.
equation: H O + Br = O + 2 Br + 2 H . See: Bray, W. C. Chem.
2 2 2 2
Rev. 1932, 10, 161.
+
51. (e) De Luca, L.; Giacomelli, G.; Masala, S.; Porcheddu, A.
(25) The amount of [Br ] was determined by titration using cyclo-
hexene in hexane (three independent experiments). After titra-
tion, usual aqueous work up was performed, and major product
from the reaction with cyclohexene was found to be trans-1,2-
(
h) Demizu, Y.; Shiigi, H.; Mori, H.; Matsumoto, K.; Onomura, O.
dibromocyclohexane, indicating the formation of Br instead of
other [Br ] species, see the Supporting Information.
2
+
Tetrahedron: Asymmetry 2008, 19, 2659. (i) Kuroboshi, M.; Goto,
K.; Tanaka, H. Synthesis 2009, 903.
(26) Because we observed vigorous evolution of gas immediately
after mixing NaBr, AcOH, TEMPO, and H O , TEMPO might
(
12) For the combination of stoichiometric amounts of oxidant and
catalytic amounts of alkali bromide salts for oxidation of alco-
hols, see: (a) Morimoto, T.; Hirano, M.; Ashiya, H.; Egashira, H.;
Zhuang, X. Bull. Chem. Soc. Jpn. 1987, 61, 4143. (b) Hirano, M.;
Morimoto, T.; Itoh, K. Bull. Chem. Soc. Jpn. 1988, 61, 3749.
2
2
promote the decomposition of H O .
2
2
(27) Farkas, L.; Perlmutter, B.; Schächter, O. J. Am. Chem. Soc. 1949,
71, 2829.
(28) NaOAc-assisted dehydrobromination like E2-elimination is an
alternative possibility for step C.
(
(
c) Hirano, M.; Morimoto, T. Bull. Chem. Soc. Jpn. 1989, 62, 4069.
d) Tohma, H.; Takizawa, S.; Maegawa, T.; Kita, Y. Angew. Chem.
(29) General Procedure for NaBr-Catalyzed Oxidation: Under a
nitrogen atmosphere, to a solution of substrate alcohol (0.5
mmol) in AcOH (1.0 mL) or AcOH–EtOAc (3:7, 2.0 mL) was
added a stock solution of aq NaBr solution (1.94 M, 25 μL) and
30% aq H O (50 μL, 0.5 mmol). After stirring the mixture for 1 h
Int. Ed. 2000, 39, 1306. (e) Surendra, K.; Krishnaveni, N. S.; Rao,
K. R. Can. J. Chem. 2004, 82, 1230. (f) Kuhakarn, C.;
Kittigowittana, K.; Pohmakotr, M.; Reutrakul, V. Tetrahedron
2
005, 61, 8995. (g) Zolfigol, M. A.; Shirini, F.; Chehardoli, G.;
2
2
Kolvari, E. J. Mol. Catal. A: Chem. 2007, 265, 272. (h) Hirashima,
S.-I.; Itoh, A. Green Chem. 2007, 9, 318.
at 60 °C, additional 30% aq H O (50 μL, 0.5 mmol) was added,
and stirring was continued for another 1 h. After cooling, the
2 2
(
13) Recently, Moriyama and Togo reported KBr-catalyzed oxidation
of alcohol with H O in the presence of PhSO H, see: Moriyama,
mixture was poured into a sat. aq NaHCO solution (ca. 30 mL)
3
with the aid of CH Cl , and the resulting mixture was extracted
2
2
3
2
2
K.; Takemura, M.; Togo, H. J. Org. Chem. 2014, 79, 6094.
with CH Cl . The combined organic layers were dried over
2 2
(
14) For the HBr- or Br -catalyzed oxidation of alcohol, see:
anhyd MgSO , filtered and concentrated in vacuo. The residue
2
4
(
a) Amati, A.; Dosualdo, G.; Zhao, L.; Bravo, A.; Fontana, F.;
Minisci, F.; Bjørsvik, H.-R. Org. Process Res. Dev. 1998, 2, 261.
b) Sharma, V. B.; Jain, S. L.; Sain, B. Synlett 2005, 173. (c) Joseph,
was chromatographed on silica gel (flash column or preparative
TLC) to afford the corresponding ketone. Caution: When the
reaction is carried out on a large scale, treatment of the com-
bined organic layers with aq Na S O solution is recommended
to avoid unexpected explosion.
1-Phenylnonan-1-one (2a): Compound 2a was obtained
(
J. K.; Jain, S. L.; Sain, B. Eur. J. Org. Chem. 2006, 590. (d) Jain, S. L.;
Sharma, V. B.; Sain, B. Tetrahedron 2006, 62, 6841. (e) Uyanik,
M.; Fukatsu, R.; Ishihara, K. Chem. Asian J. 2010, 5, 456.
2
2
3
(
15) In our previous study on α-acetoxylation H O was not effec-
according to the general procedure and purified by preparative
TLC (hexane–EtOAc, 20:1) as a colorless oil. H NMR (500 MHz,
2
2
1
tive; see ref. 3. Use of other organic solvents (EtOAc, MeCN,
DMF) instead of AcOH resulted in no reaction.
CDCl ): δ = 7.96 (d, J = 7.5 Hz, 2 H), 7.54–7.57 (m, 1 H), 7.45–
3
(
16) In our previous study, stepwise addition of oxidant was found to
be effective; see ref 3. Ishihara and co-workers have also
reported stepwise or slow addition of oxidant in their iodide
salt catalyzed oxidation, see: Uyanik, M.; Suzuki, D.; Watanabe,
M.; Tanaka, H.; Furukawa, K.; Ishihara, K. Chem. Lett. 2015, 44,
7.48 (m, 2 H), 2.96 (t, J = 7.5 Hz, 2 H), 1.74 (m, 2 H), 1.27–1.44
13
(m, 10 H), 0.88 (t, J = 6.9 Hz, 3 H). C NMR (125 MHz, CDCl ): δ =
3
200.6, 137.0, 132.8, 128.5, 128.0, 38.6, 31.8, 29.4, 29.3, 29.1,
24.3, 22.6, 14.1. The NMR data are in agreement with those
previously reported in literature (see ref. 30).
3
87.
(30) Vautravers, N. R.; Regent, D. D.; Breit, B. Chem. Commun. 2011,
47, 6635.
(
17) Reaction of 1g with 0.5 equiv of H O in AcOH for 1 h at 60 °C in
2
2
the absence of NaBr gave 3 and 4 in 59% and 20% yields, respec-
tively.
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Georg Thieme Verlag Stuttgart · New York — Synlett 2015, 26, A–E