Catalytic oxidation of various alcohols to the corresponding carbonyl compounds with N-chlorosuccinimide using a catalytic amount of sulfenamide

Article abstract of DOI:10.1246/cl.2001.846

Various primary and secondary alcohols were smoothly oxidized to the corresponding carbonyl compounds with N-chlorosuccinimide by using a catalytic amount of N-tert-butylbenzenesulfenamide (1) in the co-existence of potassium carbonate and molecular sieves 4A.

Full text of DOI:10.1246/cl.2001.846

846
Chemistry Letters 2001
Catalytic Oxidation of Various Alcohols to the Corresponding Carbonyl Compounds
with N-Chlorosuccinimide Using a Catalytic Amount of Sulfenamide
Teruaki Mukaiyama,* Jun-ichi Matsuo, Daisuke Iida, and Hideo Kitagawa
Department of Applied Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka, Shinjuku-ku, Tokyo 162-8601
(Received May 25, 2001; CL-010493)
Various primary and secondary alcohols were smoothly
oxidized to the corresponding carbonyl compounds with N-
chlorosuccinimide by using a catalytic amount of N-tert-butyl-
benzenesulfenamide (1) in the co-existence of potassium car-
bonate and molecular sieves 4A.
reaction of in situ formed 2 and alcohols. Several bases were
examined by taking catalytic oxidation of benzyl alcohol using
5 mol% of 1 in the co-existence of 1.1 equiv of NCS as a model
reaction. In the first place, DBU and diisopropylethylamine,
which were successfully employed in previously reported oxi-
dation of alcohols using 2, were examined. Fortunately, DBU
was found to work well as a base in the present 1-catalyzed oxi-
dation, and benzaldehyde was detected in 86% yield while
diisopropylethylamine was not effective (Entries 1 and 2). In
the above two reactions, slow addition of NCS was necessary
since NCS was obviously consumed by the interaction with
these amine bases in the reaction media.
Next, some solid bases were examined. Zinc oxide, a use-
ful solid base in the stoichiometric oxidation using 2, was found
not to be effective in the present catalytic oxidation (Entry 3).
On the other hand, dried potassium carbonate7 gave a good
result (90%) while other carbonate salts such as sodium and
cesium carbonates did not (Entries 4–6). This catalytic oxida-
tion of using potassium carbonate as a base was performed by a
simple operation since the slow addition of NCS was not neces-
sary in this case.
It is an important and challenging topic to explore an effi-
cient method for catalytic oxidation of primary and secondary
alcohols to the corresponding carbonyl compounds since more
than a stoichiometric amount of hazardous metals such as
chromium are used in conventional oxidation reactions.
Several catalytic oxidations of alcohols using transition metals
have been reported to date, and TPAP-catalyzed oxidation1 is
the most popular one among them. On the other hand, Swern
oxidation2 is a useful stoichiometric oxidation method via an
intermediate, chlorodimethylsulfonium chloride (Me2SCl+Cl–).
However, no catalytic methods for oxidation of alcohols via
such sulfonium intermediates were reported. In this communi-
cation, we would like to report a novel, highly efficient, and
widely applicable method for catalytic oxidation of alcohols to
the corresponding carbonyl compounds with N-chlorosuccin-
imide (NCS) by using a catalytic amount of N-tert-butylben-
zenesulfenamide (1) in the presence of potassium carbonate and
molecular sieves 4A (MS4A).
In previous communications, there was shown that N-tert-
butylphenylsulfinimidoyl chloride (2) smoothly oxidized vari-
ous primary and secondary alcohols to the corresponding car-
bonyl compounds in the presence of DBU or zinc oxide.3 The
troublesome problem of this oxidation was that N-tert-butylben-
zenesulfenamide (1), a reduced product of 2, should be separat-
ed from the desired carbonyl compounds after the oxidation. It
was then thought that in situ generation of 2 by oxidation of 1
using an appropriate chlorinating agent would enable 1-cat-
alyzed oxidation of alcohols, and thus the established catalytic
reaction would provide a convenient method for oxidation of
alcohols.
Further, the addition of dehydrating agents7 such as molec-
ular sieves or Drierite® improved the yield of benzaldehyde up
to 98% when potassium carbonate was used as a base (Entries
7–10). The use of anhydrous sodium sulfate or magnesium sul-
fate did not affect the 1-catalyzed oxidation (Entry 11 and 12).
After screening several chlorinating agents such as NCS,
tert-butyl hypochlorite, and chlorine for regeneration of 2 from
1, NCS4 was found to be the most promising chlorinating agent.
It was observed that 15 was oxidized with NCS to regenerate 2
along with succinimide by 1H NMR measurement (in CDCl3,
rt).6 Expectedly, benzyl alcohol was oxidized to benzaldehyde
in 93% yield in the presence of DBU (2.0 equiv) with 2 gener-
ated from more than a stoichiometric amount of 1 (1.4 equiv)
and NCS (1.5 equiv).
The above results prompted us to study in detail on the
reaction conditions in order to establish catalytic oxidation of
alcohols by using 1 and NCS (Table 1). Here, a choice of an
appropriate base was very important: that is, the base (i) should
be inert to NCS and (ii) can effectively trap HCl formed by the
Copyright © 2001 The Chemical Society of Japan

Chemistry Letters 2001
847
It was shown that the catalyst 1 played a very important
role in this oxidation since only less than 1% of benzaldehyde
was detected in the absence of 1 (Entry 8).
Various primary and secondary alcohols were smoothly
oxidized to the corresponding carbonyl compounds in high
yields with NCS by using 5 mol% of 1 in the coexistence of
potassium carbonate and MS4A as shown in Table 2. It is
noted that the present catalytic oxidation proceeded under
rather mild conditions because 2-phenylethanol was quantita-
tively oxidized to phenylacetaldehyde (Entry 7).3b Moreover,
formed carbonyl compounds were easily isolated by preparative
thin-layer chromatography (Entries 6 and 12).
A proposed catalytic cycle is shown in Figure 1. The cata-
lyst 1 was oxidized with NCS to generate sulfinimidoyl chlo-
ride 2 and succinimide as described above. The formed oxidiz-
ing agent 2 reacted with alcohols in the presence of potassium
carbonate to afford alkoxysulfilimine (3), a key intermediate of
oxidation, which decomposed to carbonyl compounds along
with the catalyst 1. Thus, a catalytic cycle was effectively
established.
General experimental procedure (Table 1, Entry 8) is as
7
follows: to a stirred suspension of MS4A7 (500 mg), K2CO3
(691 mg, 5.0 mmol), and NCS (73.4 mg, 0.55 mmol) in CH2Cl2
(1 mL) were successively added a solution of benzyl alcohol
(54.1 mg, 0.50 mmol) in CH2Cl2 (1.5 mL) and a solution of 15
(4.5 mg, 25 µmol) in CH2Cl2 (1.5 mL) at 0 °C. After the reac-
tion mixture was kept stirring at the same temperature for an
additional hour, it was quenched by adding H2O. The resulting
mixture was filtered through Celite-pad, and the filtrate was
extracted with CH2Cl2. The yield of benzaldehyde (98%) was
determined by GC-analysis using naphthalene as an internal
standard.
Reaction conditions presented here were not yet sufficient-
ly optimized, and studies on scope and limitations of the 1-cat-
alyzed oxidation are now in progress.
The present work was partially supported by Grant-in-Aids
for Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
References and Notes
1
TPAP: tetrapropylammonium perruthenate. W. P. Griffith,
S. V. Ley, G. P. Whitcombe, and A. D. White, J. Chem.
Soc., Chem. Commun., 1987, 1625.
2
3
A. J. Mancuso and D. Swern, Synthesis, 1981, 165.
a) T. Mukaiyama, J. Matsuo, and M. Yanagisawa, Chem.
Lett., 2000, 1072. b) J. Matsuo, H. Kitagawa, D. Iida, and
T. Mukaiyama, Chem. Lett., 2001, 150.
4
5
a) E. J. Corey and C. U. Kim, J. Am. Chem. Soc., 94, 7586
(1972). b) T. Mukaiyama, M. Tsunoda, and K. Saigo,
Chem. Lett., 1975, 691.
The catalyst, N-tert-butylbenzenesulfenamide (1),5a was
prepared from benzenesulfenyl chloride5b and tert-butyl-
amine. See: a) Y. Miura, H. Asada, and M. Kinoshita,
Bull. Chem. Soc. Jpn., 50, 1855 (1977). b) A. G. M.
Barrett, D. Dhanak, G. G. Graboski, and S. J. Taylor, Org.
Synth., 68, 8 (1990).
6
7
In the case of N,N-dialkylsulfenamides, alkylamino-succin-
imidosulfonium chlorides were obtained on treatment with
NCS. See: M. Haake and H. Benack, Synthesis, 1976, 308.
Powdered potassium carbonate was dried in vacuo by heat-
ing it with a heat-gun. Molecular sieves and Drierite®
were also dried in vacuo at 250 °C for 12 h.