Sulfenamide catalyzed oxidation of alcohols to the corresponding carbonyl compounds with anhydrous chloramine-T.

Article abstract of DOI:10.1248/cpb.50.1276

N-tert-Butylbenzenesulfenamide (1) catalyzed oxidation of various alcohols with stoichiometric amount of anhydrous chloramines-T (2) proceeded smoothly at room temperature to afford the corresponding carbonyl compounds in good yields.

Full text of DOI:10.1248/cpb.50.1276

1276
Notes
Chem. Pharm. Bull. 50(9) 1276—1279 (2002)
Vol. 50, No. 9
Sulfenamide Catalyzed Oxidation of Alcohols to the Corresponding
Carbonyl Compounds with Anhydrous Chloramine-T
Hideo KITAGAWA and Teruaki MUKAIYAMA*
The Kitasato Institute, Center for Basic Research; 6–15–9 (TCI) Toshima, Kita-ku, Tokyo 114–0033, Japan.
Received April 19, 2002; accepted June 12, 2002
N-tert-Butylbenzenesulfenamide (1) catalyzed oxidation of various alcohols with stoichiometric amount of
anhydrous chloramines-T (2) proceeded smoothly at room temperature to afford the corresponding carbonyl
compounds in good yields.
Key words catalytic oxidation; N-tert-butylbenzenesulfenamide; chloramine-T
Oxidation of primary and secondary alcohols to the corre- The result suggested that it was the position of substitutent in
sponding carbonyl compounds is one of the most important benzene ring which influenced reaction velocity. It was ex-
methods and to develop the catalytic oxidation is, therefore, pected that N-chloro-N-sodio-4-chlorobenzenesulfonamide9)
quite a challenging. There are a few catalytic methods having electron-withdrawing substitutent (-Cl) at para posi-
reported for the oxidation of alcohols including the reac- tion of the benzene ring to behave as a stronger oxidant than
tion promoted by transition metal catalysts such as ruthe- that of 2. On the contrary, 2 was found to be the more effec-
nium and also by using oxidants such as N-(arylseleno)-4- tive chlorinating agent (Entry 1, 4). After screening the oxi-
chlorobenzenesulfonamide,1) 2,2,6,6-tetramethylpiperidin-1- dation reaction using various sulfenamide derivatives10) as
yloxyl (TEMPO)2) or tetra-n-propylammonium perruthenate catalysts, it was shown that the substitutent of benzene ring
(TPAP).3,4) However, the use of toxic oxidants and compli- of the sulfenamide was not influential to this oxidation (Table
cated operations in such oxidations were still disadvanta- 2, Entry 2—5), but the experimental procedures, that is, the
geous.
way of adding the reagents were more influential to the
Recently, it was shown from our laboratory that various al- yields of carbonyl compounds. For example, aldehyde was
cohols are oxidized smoothly by using a stoichiometric obtained in 69% when the mixture of benzyl alcohol and 2 in
amount of N-tert-butylphenylsulfinimidoyl chloride (3) in the CH2Cl2 were added to a solution of 1 in CH2Cl2 while yield
presence of DBU5) or zinc oxide.6) In the above oxidation, decreased down to 58% when benzyl alcohol and 1 in
however, a problem in the separation of N-tert-butylbenzene- CH2Cl2 were added 2. When a mixture of 1 and 2 in CH2Cl2
sulfenamide (1), a reduced product of 3, from the formed was added to a solution of benzyl alcohol in CH2Cl2, on the
carbonyl compounds after the oxidation had to be solved. other hand, benzaldehyde was not obtained. Next, effects of 1
More recently, 1 catalyzed oxidation of alcohols by using a and solvents were examined (Table 3). When 1 was not used
stoichiometric amount of N-chlorosuccinimide (NCS) in the in this procedure, the desired product was not obtained at all
presence of potassium carbonate as a base and molecular (Entry 1). Among the solvents examined, CH2Cl2 gave the
sieves 4A (MS4A) as a dehydrating agent was reported.7) best result, though the oxidation stopped after 1 h and ben-
The facile in situ generation of 3, a key oxidation, by zaldehyde was obtained in moderate yield. On the other
chloronation of 1 with NCS enabled the above catalytic oxi- hand, the yield of bezaldehyde was improved up to 84% after
dation.
In this note, we would like to report an alternative method
being kept stirring in toluene for a long time. The same
for catalytic oxidation of alcohols by using other chlorinating
agent, chloramine-T, which behaves both as an oxidizing
agent and a base, in place of NCS. Chloramine-T (2)8) is
known as inexpensive, commercially available reagent and it
behaves as a source of positive halogen species. Moreover, it
has an advantageous point that the catalytic oxidation could
be performed by a simple operation without adding any bases
and dehydrating agents. p-Toluenesulfonamide, formed by
the oxidation, was easily separated after the reaction and the
recovered amide was easily converted to chloramine-T on
treatment with aqueous sodium hypochlorite.
Table 1. Effect of Various Substituted Chloramines
Yield (%)a)
benzaldehyde
Entry
1
R
Temp (°C) Time (h)
0
1.0
69
First, catalytic oxidation of benzyl alcohol to benzalde-
hyde was examined using 0.3 eq of 1 and 1.2 eq of several
anhydrous N-chloro-N-sodio arylsulfonamides as a model re-
action (Table 1). Commercially sulfonamide hydrate was de-
hydrated by heating it up to 100 °C or by keeping it standing
over phosphorous pentoxide under vacuum. When N-chloro-
N-sodio-2-methylbenzenesulfonamide was used, the oxida-
tion reaction proceeded slower than that of using 2 (Entry 2).
2
3
0
(rt)
1.0
(75.5)
22
(71)
0
(rt)
0
1.0
(69.5)
1.0
Trace
(60)
3
4
5
0
1.0
Trace
a) Determined by GC-analysis. rt: room temperature.
To whom correspondence should be addressed. e-mail: mukaiyama@abeam.ocn.ne.jp
© 2002 Pharmaceutical Society of Japan

September 2002
1277
Table 2. Effect of Substituted Sulfenamides
Table 4. Catalytic Oxidation of Various Alcohols
Yield (%)a)
aldehyde
Yield (%)a)
benzaldehyde
Entry
Alcohol
Temp
Time (h)
Entry
1
Sulfenamide
Temp (°C) Time (h)
1
2
3
4
5
PhCH2OH
p-MeOC6H4CH2OH
p-NO2C6H4CH2OH
Ph(CH2)3OH
0–rt
rt
rt
rt
rt
6.0
6.0
20.0
7.5
84
PhSNHtBu (1)
0–rt
(0)
6.0
(1.0)
84b)
(69)
97
80b)
84
Ph2CHOH
24.0
71b,c)
2
3
0–rt
(0)
65.0
(3.0)
29
(5)
6
7
8
9
0–rt
rt
4.0
3.5
82
83
80
49
0
0
1.0
1.0
4
4
5
Trace
rt
14.0
17.0
0–rt
(0)
6.0
(1.0)
61b)
(29)
0–rt
10
11
12
CH3(CH2)7OH
BzO(CH2)8OH
THPO(CH2)8OH
0–rt
rt
0–rt
17.0
19.0
23.0
92
a) Determined by GC-analysis. b) Toluene was used as a solvent.
63b)
69b)
Table 3. Effect of Solvent and Amounts of Chloramine-T
a) Determined by GC-analysis. b) Isolated yield. c) 2 (2.0 eq) was used.
Yield (%)a)
benzaldehyde
Entry
Solvent
Time (h)
1b)
2
3
4
5
6
7
8
9
CH2Cl2
CH2Cl2
CH2Cl2
Toluene
Benzene
BTFd)
MeCN
Et2O
THF
1
21
18
6
2
5
5
23
1
N.R.
69 (69)
70 (68)
84 (9)
82 (19)
84 (20)
12 (12)
45 (N.R.)
8
a) Determined by GC-analysis. b) No catalyst. c) Reaction condition is 0 °C,
1 h in parenthesis. d) Trifluoromethyl benzene. N.R.: No reaction.
Fig. 1
results were obtained when aromatic solvents were used
(Entry 5, 6) while acetonitrile, diethylether, and tetrahydrofu-
ran (THF) were not suitable for this oxidation of alcohols.
Further, it was observed that the yield of benzaldehyde was
not influenced by the amount of 2. Finally, the above men-
tioned oxidation system, 1 and 2, was applied to the catalytic
oxidation of various alcohols to the corresponding carbonyl
compounds (Table 4). The desired aldehydes were obtained
in good yields whithout any noticeable overoxidation to car-
boxylic acids under these conditions whereas secondary al-
cohols were oxidized to the corresponding ketones in moder-
ate yields.
Experimental
General All melting points were determined on a Yanagimoto micro
melting point apparatus (Yanaco MP-S3) and are uncorrected. Infrared (IR)
spectra were recorded on a Horiba FT300 FT-IR spectrometer. 1H-NMR
spectra were recorded on a JEOL EX270 (270 MHz) or a JNM-LA300 (300
MHz) spectrometer; chemical shifts (d) are reported in parts per million rel-
ative to tetramethylsilane. Splitting patterns are designated as a s, singlet; d,
doublet; t, triplet; q, quartet; m, multiplet; br, broad. 13C-NMR spectra were
recorded on a JEOL EX270 (68 MHz) or a JNM-LA300 (75 MHz) spec-
trometer with complete proton decoupling. Chemical shifts are reported in
parts per million relative to tetramethylsilane with the solvent resolution
mass spectra (HR-MS) were recorded on a JEOL JMS-700 mass spectrome-
ter. Analytical gasliquid chromatography (GLC) was performed on Shi-
madzu GC-17A instrument equipped with a flame ionizing detector and a
capillary column of OV-101 (0.25 mmϫ50 m) or CBP10 (0.25 mmϫ25 m)
using helium as carrier gas. Analytical TLC was performed on Merk pre-
coated TLC plates (silica gel 60 GF254, 0.25 mm). Silica-gel column chro-
matography was carried out on Merk silica gel 60 (0.063—0.200 mm).
Preparative thin-layer chromatography (PTLC) was carried out on silica gel
A proposed catalytic cycle is shown in Fig. 1. The catalyst
1 was oxidized with 2 to generate mainly 3 along with 4. The
formed oxidizing agent 3 successively reacted with alcohols
in the presence of 4 to afford alkoxysulfilimine (5), a key in-
termediate of the oxidation, which decomposed to form car- Wakogel B-5F. Unless otherwise noted, commercially available reagents
were used without purification. Dry solvents were prepared by distillation
under appropriate drying agents. The oxidation products were identified by
bonyl compounds along with regeneration of the catalyst 1
and thus a catalytic cycle was effectively established.
comparing those authentic samples with their gas chromatography (GC) re-
As reaction conditions presented here have not yet been
1
tention times, spectroscopic data such as H-, 13C-NMR, and on analytical
sufficiently optimized, the continuous studies are now in
progress.
TLC. All reactions were carried out under an atmosphere of argon in oven-
dried glassware with magnetic stirring.

1278
Vol. 50, No. 9
Typical Experimental Procedure for Oxidation of Alcohols The ex- chromatography (silica gel, hexanes–AcOEt) to give the desired product an
perimental procedure (Table 4, Entry 1) is described: to a stirred suspension orange oil (186.2 mg, 8.19ϫ10Ϫ1 mmol, 97%). IR (neat) 1201, 1259, 1334,
of 2 (0.36 mmol) and benzyl alcohol (0.3 mmol) in toluene (1.5 ml) were 1585, 2968 cmϪ1 1H-NMR (300 MHz, CDCl3) d: 1.17 (9H, s), 3.98 (1H,
;
added successively a solution of 1 (0.09 mmol) in toluene (1 ml) at 0 °C. br s), 7.20 (1H, dd, Jϭ4.8, 8.1 Hz), 8.48 (1H, dd, Jϭ1.5, 8.1 Hz), 8.73 (1H,
After the reaction mixture was kept stirring at room temperature for 6 h, it dd, Jϭ1.5, 4.8 Hz); 13C-NMR (68 MHz, CDCl3) d: 29.01, 55.36, 118.93,
was quenched by adding H2O and the resulting mixture was extracted with 133.58, 140.00, 152.99, 164.64; HR-FAB-MS (positive-ion mode,
Et2O. The yield of benzaldehyde was determined by GC-analysis using glycerolϩm-nitrobenzyl alcohol as a matrix) m/z: 228.0808 [MϩH]ϩ (Calcd
naphthalene as an internal standard.
for C9H14N3O2S: 228.0802).
N-tert-Butyl-2-methylbenzenesulfenamide (Table 2, Entry 5) To a
8-Benzoyloxyoctanal (Table 4, Entry 11)11,12) IR (neat) 709, 1103,
1
1712, 2738, 2823 cmϪ1; H-NMR (300 MHz, CDCl3) d: 1.38 (6H, m), 1.64 stirred solution of 2-methylbenzenesulfenyl chloride (4.27 g, 26.9 mmol) in
(2H, q, Jϭ7.2 Hz), 1.78 (2H, q, Jϭ6.6 Hz), 2.42 (2H, dt, Jϭ1.8, 7.5 Hz), dry dichloromethane (60.0 ml), solution of tert-butylamine (4.13 g, 56.5
4.31 (2H, t, Jϭ6.6 Hz), 7.43 (2H, m), 7.55 (1H, m), 8.04 (2H, m), 9.75 (1H,
t, Jϭ1.8 Hz); 13C-NMR (68 MHz, CDCl3) d: 21.82, 25.72, 28.51, 28.89,
28.89, 43.67, 64.84, 128.21, 129.38, 130.32, 132.71, 166.50, 202.59.
mmol) in dry dichloromethane (40.0 ml) was added dropwise during 40 min
at Ϫ78 °C. After the reaction mixture was stirred for 30 min at the same
temperature, the mixture was added H2O, and extracted with dichloro-
8-Tetrahydropyranyloxyoctanal (Table 4, Entry 12)13,14) IR (neat) methane (50 mlϫ2). Combined organic extracts were washed with brine,
1735, 1120 cmϪ1
;
1H-NMR (300 MHz, CDCl3) d: 1.35—2.15 (16H, m), dried over anhydrous Mg2SO4, filtered, and concentrated to give a colorless
2.43 (2H, td, Jϭ1.7, 7.3 Hz), 3.37 (1H, td, Jϭ6.6, 9.6 Hz), 3.50 (1H, m), oil. The crude product was purified by bulb to bulb distillation under re-
3.73 (1H, td, Jϭ6.6, 9.6 Hz), 3.86 (1H, m), 4.57 (1H, m), 9.76 (1H, t, Jϭ
duced pressure to give the desired product as colorless oil (1.21 g, 6.19
1.7 Hz); 13C-NMR (68 MHz, CDCl3) d: 19.66, 21.96, 25.45, 26.00, 29.03, mmol, 23%). bp 160.0—170.0 °C/106.7 Pa (bulb to bulb distillation); IR
1
29.13, 29.61, 30.73, 43.82, 62.32, 67.50, 98.83, 202.82.
(neat) 1203, 1361, 1462, 2969 cmϪ1; H-NMR (300 MHz, CDCl3) d: 1.19
N-tert-Butylbenzenesulfenamide (Table 2, Entry 1)15,16) To a stirred (9H, s), 2.23 (3H, s), 2.60 (1H, br s), 6.98 (1H, ddd, Jϭ1.1, 7.2, 14.9 Hz),
solution of tert-butylamine (13.6 g, 185 mmol) in dry ether (150 ml), solu-
7.03 (1H, d, Jϭ7.2 Hz), 7.19 (1H, ddd, Jϭ1.2, 8.1, 14.9 Hz), 7.65 (1H, dd,
tion of benzenesulfenyl chloride (12.2 g, 84.2 mmol) in dry ether (30 ml)
Jϭ1.1, 8.1 Hz); 13C-NMR (68 MHz, CDCl3) d: 18.55, 29.17, 54.66, 122.35,
was added dropwise during 30 min at 0 °C. After the reaction mixture was 123.86, 125.87, 129.51, 131.47, 142.51; MS [EIϩ] m/z 195 [Mϩ].
stirred for 2 h at room temperature, the resulting white suspension was fil-
N-Chloro-N-sodio-4-chlorobenzenesulfonamide19,20) To a stirred solu-
tered and the filtrate was concentrated. The crude product was distilled to tion of NaOH (4.0 g, 100.0 mmol) in H2O (50.0 ml), 4-chlorobenzenesulfon-
give the desired product as colorless oil (9.53 g, 62%). bp 94—95 °C/933 Pa; amide (19.5 g, 100.0 mmol) was added at 0 °C. And the reaction mixture was
IR (neat) 1095, 1203, 1365, 3286 cmϪ1 1H-NMR (270 MHz, CDCl3) added cold 12% aqueous sodium hypochlorite (105.0 mmol, 65 ml) at the
;
d: 1.18 (9H, s), 2.79 (1H, br s), 7.00—7.10 (1H, m), 7.20—7.30 (2H, m), same temperature. After the reaction mixture was stirred for 44 h at room
7.30—7.40 (2H, m); 13C-NMR (68 MHz, CDCl3) d: 29.14, 54.71, 122.35, temperature, the resulting white suspension was filtered and the filtered was
124.40, 128.34, 144.35.
washed with H2O. The crude product was purified by recrystallization from
H2O to afford the desired product as white crystal, and dried at 80 °C under
N-tert-Butyl-2-nitrobenzenesulfenamide (Table 2, Entry 2) To
a
stirred solution of 2-nitrobenzenesulfenylchloride (9.48 g, 50.0 mmol) in reduced pressure. mp 190.0 °C (decomp); IR (KBr) 1091, 1140, 1253 cmϪ1
;
dry dichloromethane (100.0 ml), solution of tert-butylamine (7.31 g, 100.0
mmol) in dry dichloromethane (40.0 ml) was added dropwise during 40 min 8.6 Hz); 13C-NMR (68 MHz, DMSO-d6) d: 127.87, 128.80, 133.95, 144.27.
at 0 °C. After the reaction mixture was stirred for 12 h at room temperature, stirred suspension
N-Chloro-N-sodiomethanesulphonamide21) To
1H-NMR (300 MHz, DMSO-d6) d: 7.43 (2H, d, Jϭ8.6 Hz), 7.62 (2H, d, Jϭ
a
the resulting orange suspension was added brine (50.0 ml), and the mixture of N,N-dichloromethanesulphonamide (4.06 g, 42.7 mmol) and methane-
was extracted with dichloromethane (50 mlϫ2). Combined organic extracts sulphonamide (7.00 g, 42.7 mmol) in H2O (70.0 ml), aqueous NaOH (3.41 g,
were washed with brine, dried over anhydrous MgSO4, filtered, and concen- 85.4 mmol) in H2O (85 ml) was added dropwise at 0 °C. After the reaction
trated to give an orange oil. The crude product was purified by column chro- mixture was stirred for 25 h at room temperature, the resulting white suspen-
matography (silica gel, hexanes–AcOEt) to give the desired products yellow sion was filtered and the filtered was washed with acetone and dried (P2O5)
crystal (9.00 g, 79.5 mmol, 80%). mp 38.0—39.0 °C; IR (KBr) 1200, 1295, at room temperature. The desired product as was obtained as a white powder
1
1333, 1504, 3325 cmϪ1; H-NMR (300 MHz, CDCl3) d: 1.23 (9H, s), 2.66 (5.82 g, 38.4 mmol, 90%). mp 88.0—100.0 °C (decomp); IR (KBr) 1026,
(1H, br s), 7.21 (1H, m), 7.61 (1H, m), 8.26 (2H, m); 13C-NMR (68 MHz, 1112, 1245 cmϪ1; 1H-NMR (300 MHz, DMSO-d6) d: 2.70 (3H, s); 13C-NMR
CDCl3) d: 29.25, 54.87, 124.18, 125.36, 125.46, 133.32, 142.59, 147.17; (68 MHz, DMSO-d6) d: 147.87.
high resolution (HR)-FAB-MS (positive-ion mode, m-nitrobenzyl alcohol as
a matrix) m/z: 227.0848 [MϩH]ϩ (Calcd for C10H15N2O2S: 227.7500).
Acknowledgements The authors are grateful to Miss S. Miki and Mrs.
N-tert-Butyl-2-carbomethoxybenzenesulfenamide (Table 2, Entry N. Nishikawa, Meiji Seika Kaisha, Ltd. for measurement of the mass and
3)17,18) To a stirred solution of 2-methylatebenzenesulfenyl chloride (1.81 NMR spectra.
g, 10.8 mmol) in dry dichloromethane (20.0 ml), solution of tert-butylamine
(1.58 g, 21.6 mmol) in dry dichloromethane (10.0 ml) was added dropwise
during 5 min at 0 °C. After the reaction mixture was stirred for 2 h at room
temperature, the resulting white suspension was added H2O, brine, and the
mixture was extracted with dichloromethane (50 mlϫ2). Combined organic
extracts were washed with brine, dried over anhydrous Mg2SO4, filtered, and
concentrated to give a white solid. The crude product was purified by col-
umn chromatography (silica gel, hexanes–AcOEt) to give the desired prod-
uct as white solid (683.9 mg, 2.86 mmol, 26%). mp 83.0 °C; IR (KBr) 1100,
1268, 1310, 1700, 3289 cmϪ1; 1H-NMR (300 MHz, CDCl3) d: 1.22 (9H, s),
2.54 (1H, br s), 3.91 (3H, s), 7.10 (1H, ddd, Jϭ0.6, 7.8, 15.6 Hz), 7.49 (1H,
ddd, Jϭ1.2, 8.1, 15.6 Hz), 7.97 (1H, dd, Jϭ1.2, 7.8 Hz), 8.16 (1H, d, Jϭ8.1
Hz); 13C-NMR (68 MHz, CDCl3) d: 29.21, 51.96, 54.52, 123.14, 123.41,
123.47, 130.78, 132.18, 150.84, 166.94; HR-FAB-MS (positive-ion mode,
glycerolϩm-nitrobenzyl alcohol as a matrix) m/z: 239.0975 [MϩH]ϩ (Calcd
for C12H17NO2S: 239.0980).
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