Oxidative carbon-carbon bond cleavage reaction of 1,2-diamines and 1,2-amino alcohols under an oxygen atmosphere

Article abstract of DOI:10.1016/S0040-4039(01)01945-1

Under an atmosphere of oxygen 1,2-diamines underwent clean oxidative cleavage in the presence of BF₃·OEt₂ to give imines in good to excellent yields. 1,2-Amino alcohols were also cleaved under the same conditions to give imines and a

Full text of DOI:10.1016/S0040-4039(01)01945-1

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 8865–8868
Oxidative carbonꢀcarbon bond cleavage reaction of 1,2-diamines
and 1,2-amino alcohols under an oxygen atmosphere
Makoto Shimizu* and Hiroaki Makino
Department of Chemistry for Materials, Mie University, Tsu, Mie 514-8507, Japan
Received 15 August 2001; revised 9 October 2001; accepted 12 October 2001
Abstract—Under an atmosphere of oxygen 1,2-diamines underwent clean oxidative cleavage in the presence of BF ·OEt to give
3
2
imines in good to excellent yields. 1,2-Amino alcohols were also cleaved under the same conditions to give imines and aldehydes
in good yields. © 2001 Elsevier Science Ltd. All rights reserved.
1
1
Although oxidative cleavage of 1,2-diols constitutes one
of the most important transformations which involve
N-alkylation-coupling reaction. During these investi-
gations we have been interested in the selective oxida-
tive cleavage of produced 1,2-diamines and 1,2-amino
alcohols, since they sometimes underwent cleavage
reactions upon standing in open air in the presence of a
certain acid. This report describes a simple and ready
method for the oxidative cleavage of 1,2-diamines and
1
2
use of periodic acid, lead tetraacetate, activated
3
4
MnO , and pyridinium chlorochromate, that of 1,2-
2
diamines and/or amino alcohols has not been studied in
detail. This may be due to lack of general methodolo-
gies for such transformations. Only limited examples
involve use of dimethyldioxirane for cleavage of 1,2-
1
,2-amino alcohols to give the corresponding imines
and aldehydes in high yields (Scheme 1).
5
diamines and sodium periodate or periodic acid for
6
1
,2-amino alcohols, respectively. In connection with
growing interests in the compounds containing 1,2-
diamino and/ or amino alcohol moieties, selective trans-
formation of such functionalities has received
The initial examination was carried out using N,N-
diaryl-1,2-diphenylethane-1,2-diamine as substrate in
the presence of various acids under an oxygen atmo-
7
,8
considerable preparative interests.
1
2
sphere, and the results are summarized in Table 1.
We have been interested in the preparation of 1,2-
diamines and 1,2-amino alcohols in a diastereo- and
enantioselective manner, and have already disclosed
The cleavage reaction of N,N-bis-(4-methoxyphenyl)-
1,2-diphenylethane-1,2-diamine 1 (R=Ph, Ar=p-An)
in the absence of acids gave the imine 2 in moderate
yield even after 46 h (entry 1). While the use of protic
9
asymmetric imino pinacol coupling, stereoselective
10
reduction of 1,2-diimines and 1,2-imino ketones, and
Ar
Ar
NH
N
2
R
R
R
H
HN
Ar
2
1
Ar
NH
Ar
H
O
N
Ph
R
+
Ph
H
R
OH
3
2
4
Scheme 1.
*
0
Corresponding author. Tel.: +81-59-231-9413; fax: +81-59-231-9413; e-mail: mshimizu@chem.mie-u.ac.jp
040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)01945-1

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866
M. Shimizu, H. Makino / Tetrahedron Letters 42 (2001) 8865–8868
a
Table 1. Cleavage of 1,2-diamines
Ar
Ar
NH
N
Acid (2.5 eq), O atmosphere
2
2
R
R
o
R
H
CD CN, 0 C ~ r.t.
3
HN
Ar
2
1
Entry
R
Ar (dl:meso)
4-MeOC H (50:50)
Acid
Time (h)
Yieldb (%)
67
1
2
3
4
5
6
7
8
9
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
None
MsOH
TsOH
TMSOTf
AlCl3
46
18.5
1.5
2.5
1.5
134
1
1
91
1
1
1
46
144
114
165
120
6
4
c
4-MeOC H (50:50)
25
21
6
4
d
4-MeOC H (50:50)
6
4
4-MeOC H (50:50)
77
75
43
6
4
4-MeOC H (50:50)
6
4
e
4-MeOC H (50:50)
BF ·Et O
6
4
3
2
f
4-MeOC H (50:50)
BF ·Et O
93(67)
96
6
4
3
2
g
4-MeOC H (50:50)
BF ·Et O
6
4
3
2
Ph (73:27)
BF ·Et O
69
82
87
70
58
3
2
10
11
12
13
14
15
16
17
2,4-(MeO) C H (13:87)
BF ·Et O
2
6
3
3
2
4-MeSC H (64:36)
BF ·Et O
6
4
3
2
h
4-MeC H (55:45)
BF ·Et O
6
4
3
2
i
4-ClC H (69:31)
BF ·Et O
6
4
3
2
j
4-CF C H (50:50)
BF ·Et O
23
3
6
4
3
2
4-MeOC H
c-Hex
Et
Ph (59:41)
4-MeOC H (100:0)
BF ·Et O
67
6
4
3
2
k
BF ·Et O
63
6
4
3
2
4-MeOC H (100:0)
BF ·Et O
0k,l
6
4
3
2
a
b
c
d
e
f
Reaction conditions; see Ref. 12.
Determined by 1H NMR using 1,1,2,2-tetrachloroethane as an internal standard.
PhCHO was obtained in 46% yield.
PhCHO was obtained in 53% yield.
BF ·Et O (2.0 equiv.) was used, and the reaction was run under an Ar atmosphere.
3
2
Isolated yield in the parenthesis.
In the presence of MS4A.
The starting material was recovered in 20%.
PhCHO was obtained in 33% yield.
PhCHO was obtained in 65% yield.
The reaction was run at 0–70°C.
g
h
i
j
k
l
The starting material was recovered unchanged.
acids such as methanesulfonic acid and p-toluenesul-
fonic acid gave the cleaved imines in low yields due to
the hydrolysis of the produced imines (entries 2–3), that
of trimethylsilyl trifluoromethanesulfonate or alu-
minum chloride effected the cleavage in moderate yields
ever, the diethyl substituted substrate did not undergo
oxidative cleavage, but gave only the recovered starting
material (entry 17). Under the optimum conditions
found for the oxidative cleavage of 1,2-diamines, a
variety of 1,2-amino alcohols underwent a similar reac-
1
3
(
entries 4–5). Among the Lewis acids screened the use
tion, and the results are summarized in Table 2.
of boron trifluoride etherate gave the imine in excellent
yield (entry 7). The control experiment was carried out
under an argon atmosphere instead of oxygen, and in
this case, the imine was formed in low yield, (entry 6).
This result indicates that although the oxygen present
in the solvent effects the cleavage to some extent, the
reaction conducted under an oxygen atmosphere is
Since in the absence of molecular sieves 4 A, a consider-
,
able amount of carboxylic acid was formed as a by-
product (entry 1), the oxidative cleavage of 1,2-amino
alcohols were carried out in their presence. The amount
of MS4A is important to suppress the formation of
undesired carboxylic acid. While in the presence of
MS4A (1.5 g/mmol), the aldehyde 4 was obtained in
87% yield with formation of a small amount of the
carboxylic acid, the use of an increased amount of
MS4A (2.0 g/mmol) gave only the imine 2 and the
aldehyde 4 in excellent yields, respectively (entries 2 and
3). As in the cases with diamines, the reaction of
1,2-amino alcohols possessing an electron-donating
group on the nitrogen atom proceeded to give the
cleaved products in high yields in short reaction times
(entries 3–5).
much effective. In the presence of molecular sieves 4 A
a slight increase in the product yield was observed
entry 8). The cleavage reaction of 1,2-diamines with an
,
,
(
electron-donating group on the nitrogen atom pro-
ceeded to give the imines in high yield in a short
reaction time (entries 7, 8, 10–12), whereas in the case
of 1,2-diamines possessing an electron-withdrawing
group on the nitrogen atom and that of the cyclo-hexyl
derivative, the reactions were relatively slow, giving the
imines in moderate yields (entries 13, 14 and 16). How-

M. Shimizu, H. Makino / Tetrahedron Letters 42 (2001) 8865–8868
8867
a
Table 2. Oxidative cleavage of 1,2-amino alcohols
Ar
NH
BF3•OEt2 (2.5 eq), O2 atmosphere
MS 4A (2.0 g / mmol)
Ar
H
O
N
Ph
+
R
Ph
H
o
R
CD CN, 0 ~ 70 C
3
OH
3
2
4
b
b
Entry
R
Ar (syn:anti )
4-MeOC H (65:35)
Time (h)
2 (%)
4 (%)
1
2
3
4
5
6
7
Ph
Ph
Ph
Ph
Ph
Ph
c-Hex
1.0
2.2
3.5
3.5
3.5
5.0
2.0
73
93
98
89
88
56
51
22c
6
4
d
4-MeOC H (65:35)
87
6
4
2-MeOC H (52:48)
99
93
94
80
60
6
4
4-MeSC H (60:40)
6
4
Ph (54:46)
4-ClC H (45:55)
6 4
4-MeOC H (77:23)
6 4
a
Reaction conditions; see Ref. 13.
Determined by 1H NMR using 1,1,2,2-tetrachloroethane as an internal standard.
PhCOOH was obtained in 43% yield when the reaction was carried out in the absence of MS4A.
b
c
d
MS4A (1.5 g/mmol) was used.
When oxidation reagents such as lead tetraacetate and
periodates are used for the cleavage of 1,2-diols, the
apparent necessity to form a cyclic ester, prior to the
oxidative cleavage results in significant difference in the
further CꢀC bond forming reactions. The cleavage reac-
tion in the presence of tetraallylstannan gave the allyl-
ated product 5 in 74% (Scheme 3), indicating that the
present reaction may be used for the in situ generation
of relatively unstable imines.
14
rates of cleavage of diastereoisomeric 1,2-diols.
Regarding the effect of the stereochemistry of the
amino alcohols on present type of oxidative cleavage,
the following syn- and anti-isomers were subjected to
the reaction conditions, and the results are shown in
Scheme 2.
The present cleavage reaction may proceed via the
following intermediates. First, the nitrogen atom of
1,2-diamine is coordinated with boron tirfluoride ether-
ate, and subsequently attacked by molecular oxygen to
form a hydroperoxyamine 6. The CꢀC bond cleavage
reaction proceeds to give the imine 2 and hydrogen
peroxide, which in turn oxidizes the starting diamine as
in the case with oxygen to form a hydroxyamine 7. This
Both diastereomers were cleaved smoothly in good
yields, and there was not a significant difference in the
rate of oxidation. The present reaction is used for
pAn
pAn
NH
BF •OEt (2.5 eq), O
MS 4A (2.0 g / mmol)
O
3
2
2
N
+
Ph
Ph
Ph
H
o
Ph
H
CD CN, 0 C ~ r.t., 11.0 h
3
OH
2
4
p
syn-3 (R = Ph, Ar = An)
9
3%
98%
(syn : anti = >99 : <1)
pAn
pAn
NH
BF •OEt (2.5 eq), O
2
MS 4A (2.0 g / mmol)
3
2
O
N
Ph
+
Ph
Ph
H
o
Ph
H
CD CN, 0 C ~ r.t., 11.8 h
3
OH
p
2
4
anti-3 (R = Ph, Ar = An)
97%
(syn : anti = 3 : 97)
90%
Scheme 2.
pAn
Ph
pAn
NH
Ph
HN
Ph
Sn
4
BF •OEt (2.5 eq),
(1.5 eq), O2
3
2
HN
CH CN, 0ºC ~ r.t., 19.3 h
3
pAn
5
p
1
(R = Ph, Ar = An)
74%
Scheme 3.

8
868
M. Shimizu, H. Makino / Tetrahedron Letters 42 (2001) 8865–8868
H
OOH
H
OOH
F3B
pAn N
pAn
H
H
pAnN
O2
N p
An
HNpAn
Ph
pAn N
p
N An
N
.
.
2
Ph
Ph
-H O
2 2
Ph
2
Ph
Ph
Ph
6
H O
2
2
O2
-
H O
H
OH
2
H
OH
pAnN
p
N An
pAn N
p
N An
.
.
Ph
Ph
Ph
Ph
7
Scheme 4.
hydroxyamine 7 may collapse to the imine 2 and water,
or may be oxidized to the hydroperoxyamine 6 (Scheme
4).
36, 1803–1804.
6. (a) House, H. O.; Berkowitz, W. F. J. Org. Chem. 1963,
28, 2271–2276; (b) Kovar, J. J.; Blaha, K. Coll. Czech.
Chem. Commun. 1963, 28, 2199–2206.
In conclusion, we have shown an oxidative cleavage of
,2-diamines and 1,2-amino alcohols in high yields
under very mild conditions. Since the cleaved products,
imine and/or aldehyde, may be used for further reac-
tions, the present reaction has a good potential for the
use of 1,2-diamines or amino alcohols as masked
diimines or imino carbonyl compounds.
7. Ogata, Y.; Sawaki, Y.; Shiroyama, M. J. Org. Chem.
1
1977, 42, 4061–4066.
8. Nagarkatti, J. P.; Ashley, K. R. Tetrahedron Lett. 1973,
14, 4599–4600.
9. Shimizu, M.; Iida, T.; Fujisawa, F. Chem. Lett. 1995,
609–610.
10. (a) Shimizu, M.; Kamei, M.; Fujisawa, T. Tetrahedron
Lett. 1995, 36, 8607–8610; (b) Shimizu, M.; Tsukamoto,
K.; Fujisawa, T. Tetrahedron Lett. 1997, 38, 5193–5196;
(c) Shimizu, M.; Fujisawa, T. J. Synth. Org. Chem. Jpn.
Acknowledgements
1998, 56, 672–680.
11. Shimizu, M.; Niwa, Y. Tetrahedron Lett. 2001, 42, 2829–
This research was supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education,
Culture, Sports, Science and Technology, Japan, and a
grant from the Nagase Science and Technology
Foundation.
2832.
12. A typical procedure is as follows: To a solution of
1,2-diamine (1.0 equiv.) in CD CN (0.1 mmol/ml) was
added BF ·OEt (2.5 equiv.) at 0°C under an oxygen
3
3
2
atmosphere. After the disappearance of the 1,2-diamine
on TLC, the product yield was determined by 500 MHz
1
H NMR.
References
13. Typical procedure for oxidative cleavage of 1,2-amino
alcohols: To a solution of 1,2-amino alcohol (1.0 equiv.)
1
2
3
. Jackson, E. L. Org. React. 1944, 2, 341–375.
. Mosettiig, E. Org. React. 1954, 8, 225–229.
. Ohloff, G.; Giersch, W. Angew. Chem., Int. Ed Engl.
and MS4A (2.0 g/mmol) in CD
added BF ·OEt (2.5 equiv.) at 0°C under an oxygen
3
CN (0.1 mmol/ml) was
3
2
atmosphere. After the disappearance of the 1,2-amino
alcohol was monitored on TLC, the product yields were
1
973, 12, 401–402.
1
4. Cisneros, A.; Fernandez, S.; Hernandez, J. E. Synth.
determined by 500 MHz H NMR.
Commun. 1982, 12, 833–838.
. Gagnon, J. L.; Zajac, W. W., Jr. Tetrahedron Lett. 1995,
14. Buist, G. J.; Bunton, C. A.; Miles, J. H. J. Chem. Soc.
1959, 743–748.
5