Oxoa m m on iu m Sa lts. 9. Oxid a tive
Dim er iza tion of P olyfu n ction a l P r im a r y
Alcoh ols to Ester s. An In ter estin g
â Oxygen Effect†
SCHEME 1. Dim er ic Oxid a tion of P r im a r y Alcoh ols
Nabyl Merbouh, J ames M. Bobbitt,* and
Christian Br u¨ ckner
Department of Chemistry, University of Connecticut,
Storrs, Connecticut 06269-3060
Received April 1, 2004
very highly functionalized molecules. A palladium-cata-
lyzed oxidation using an aryl halide as oxidant has been
Abstr a ct: The use of the oxidant 4-acetylamino-2,2,6,6-
tetramethylpiperidine-1-oxoammonium tetrafluoroborate in
combination with pyridine for the oxidative, dimeric esteri-
fication of primary alcohols is described. The ester is the
predominant product of the reaction with alcohols containing
a â oxygen. In the absence of a â oxygen, the corresponding
aldehyde is found in appreciable amounts, but a concentra-
tion effect can be observed. In the absence of pyridine, little
ester is formed, and no appreciable reaction takes place with
â-oxygenated compounds. δ Lactones have been prepared
from diethylene glycol and 2,2′-thiodiethanol, without sulfur
oxidation.
5
developed. Several other isolated cases of good yields of
6-15
esters have been recorded.
There are also examples
of oxidative esterification being used to prepare mixed
1
1
esters.
We noted, as have others,1,16 that alcohols containing
a â oxygen are oxidized very slowly by oxoammonium
salts in slightly acidic media. However, we have now ob-
served that primary alcohols with a â oxygen have a very
strong tendency to form dimeric esters when the oxida-
tions are carried out in the presence of pyridine, and espe-
cially when carried out in concentrated solutions, Scheme
1. A number of these oxidations are shown in Table 1. In
general, the yields are good, and the isolation of pure
esters is trivial. Only three alcohols with a â oxygen gave
In an earlier publication,1 we described the facile
oxidation of alcohols to aldehydes or ketones with an
oxoammonium salt. One of the problems encountered in
that work was that alcohols containing a â oxygen reacted
so slowly that the reaction became useless. A further
complication arose because the conditions were slightly
acidic, and blocking groups sensitive to acid were cleaved.
1
8
poor results: glycidol (20), methyl 2,3-isopropylidene-
1
7
â-D-ribofuranoside (30), and tetrahydrofurfuryl alcohol
24).17 Glycidol tends to polymerize (although its dimeric
ester appears to be stable); methyl 2,3-isopropylidene-â-
(
1
7
D-ribofuranoside gives appreciable amounts of aldehyde;
The earlier work was also carried out with an oxoam-
monium perchlorate salt, which detonated on heating.2
and tetrahydrofurfuryl alcohol gives low yields. It is
possible that these results are caused by more highly
strained situations in the hydrogen-bonded hemiacetal
intermediates (like 41, in Scheme 2) due to the three-
and five-membered oxygen rings involved.
It is of interest that diacetone galactose gives a good
yield of dimeric ester. In a previous publication, we mis-
takenly reported that this reaction gave different prod-
ucts.3
We have therefore shifted our attention to the oxoam-
monium tetrafluoroborate salt, which seems to have
identical oxidizing properties. In a more recent publica-
tion, we described the first experiments with an oxoam-
monium tetrafluoroborate salt in the presence of pyri-
dine, an essentially basic medium.3
In this paper, we would like to present the best
conditions for the preparation of 4-acetylamino-2,2,6,6-
tetramethylpiperidine-1-oxoammonium tetrafluoroborate
Compounds 20, 22, 24, and 26 are chiral, and the
resulting dimeric esters 21,18 23, 25, and 27 consist
19
17
(
the oxoammonium salt of choice; see Supporting Infor-
mation); to describe a new (for oxoammonium salts)
reaction in which highly functionalized primary alcohols
containing a â oxygen are oxidatively dimerized to esters
in high, clean yields; and to make some observations on
the mechanisms of the various reactions. In addition, the
preparation of some sulfur and oxygen containing δ
lactones will be described.
(
4) Takase, K.; Masuda, H.; Kai, O.; Nishiyama, Y.; Sakagushi, S.;
Ishii, Y. Chem. Lett. 1995, 871-872.
(5) Tamaru, Y.; Yamada, Y.; Inoue, K.; Yamamoto, Y.; Yoshida, Z.
J . Org. Chem. 1983, 48, 1286-1292.
(6) Al Neirabayeh, M.; Pujol, M. D. Tetrahedron Lett. 1990, 31,
2
273-2276.
(7) Gopinath, R.; Patel, B. K. Org. Lett. 2000, 2, 577-579.
(
8) Liu, H.-J .; Chan, W. H.; Lee, S. P. Tetrahedron Lett. 1978, 46,
4
461-4464.
(
Oxid a tive Dim er iza tion s. The oxidation of primary
alcohols to aldehydes has almost always been accompa-
nied by the formation of small amounts of a dimeric ester,
but the reaction is seldom the main one. Sodium bromate
9) Ogawa, T.; Matsui, M. J . Am. Chem. Soc. 1976, 98, 1629-1630.
(10) Sakuragi, H.; Tokumaru, K. Chem. Lett. 1974, 475-476.
(
(
11) Tohma, H.; Maegawa, T.; Kita, Y. Synlett 2003, 5, 723-725.
12) Wang, L.; Eguchi, K.; Arai, H.; Seiyama, T. Chem. Lett. 1986,
1
173-1176.
4
and sodium bisulfite have been used to prepare a series
(13) Wang, L.; Eguchi, K.; Arai, H.; Seiyama, T. Appl. Catal. 1987,
3, 107-117.
3
of esters in good yield, but the reactions did not involve
(
14) Wang, L.; Tsuda, M.; Eguchi, K.; Arai, H.; Seiyama, T. Chem.
Lett. 1987, 1889-1892.
*
To whom correspondence should be addressed. Tel: 860-486-6601.
(15) Robertson, G. R. Organic Syntheses; Wiley: New York, 1941;
Collect. Vol. I, pp 138-140.
Fax: 860-486-2981.
†
For part 8 of this series, see ref 3.
(16) Miyazawa, T.; Endo, T. J . Org. Chem. 1985, 50, 3930-3931.
(17) Papaioannou, D.; Francis, G. W.; Aksnes, D. W.; Brekke, T.;
Maartmann-Moe, K. Acta Chem. Scand. 1990, 44, 90-95.
(18) Razuvaev, G. A.; EÄ tlis, V. S.; Beshenova, E. P. J . Org. Chem.
USSR (Engl. Transl.) 1966, 2, 2003-2006.
(
(
(
1) Bobbitt, J . M. J . Org. Chem. 1998, 63, 9367-9374.
2) Bobbitt, J . M. Chem. Eng. News 1999, 77, 6.
3) Merbouh, N.; Bobbitt, J . M.; Br u¨ ckner, C. Tetrahedron Lett. 2001,
4
2, 8793-8796.
1
0.1021/jo049461j CCC: $27.50 © 2004 American Chemical Society
Published on Web 06/26/2004
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J . Org. Chem. 2004, 69, 5116-5119