Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-05-21
2004-03-09
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S322000, C568S347000, C568S349000, C568S361000, C568S362000, C568S433000, C568S460000
Reexamination Certificate
active
06703527
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for producing an aldehyde or a ketone by the Oppenauer oxidation from a corresponding allyl alcohol as a starting material.
RELATED ART
Processes of oxidation of allyl alcohols to give corresponding aldehydes or ketones are important reactions in the field of organic synthesis. A typical example of the oxidations includes the Oppenauer oxidation. The Oppenauer oxidation comprises a reaction in which a carbonyl compound as a hydride acceptor and an alcohol to be oxidized are converted into an alcohol and a carbonyl compound via a 6-membered transition state with hydride transfer in the presence of a basic catalyst such as metal alkoxides. Acetone, cyclohexanone, benzaldehyde and the like are known as the hydride acceptor, and metal alkoxides such as aluminum alkoxides and potassium tert-butoxide are known as the catalyst.
This reaction is highly selective and free from influence on a carbon-carbon double and triple bonds, amino groups, halogen, cyano groups, acetal groups, acyl groups and the like. Therefore, the reaction is an extremely useful compared to many other oxidations. However, this reaction suffers from some drawbacks. For example, this reaction is performed at a high temperature, and it requires a large excess of a hydride acceptor and a more than stoichiometric amount of a catalyst.
In order to solve these problems, reactions have recently been reported in which a catalytic amount of zirconium alkoxide (K. Krohn, et al., Synthesis 1996, 1341), zirconium complex (Y. Ishii, et al., J. Org. Chem. 1986, 51, 240), ruthenium complex (M. L. S. Almeida, et al., J. Org. Chem. 1996, 61, 6587), samarium alkoxide (J. L. Namy, et al., J. Org. Chem. 1984, 49, 2045), arylboron compounds (Japanese Patent Unexamined Publication (Kokai) No. 11-228479) or aluminum compounds (T. Ooi, et al., Angew. Chem. Int. Ed. 1998, 37, 2347) is used as the Oppenauer oxidation catalyst. However, industrial applications of these catalysts are limited from a viewpoint of their costs.
Another reaction has been reported in which aluminum alkoxide, a rather inexpensive material, is used in a catalytic amount and furfural is used as a hydride acceptor (Japanese Patent Unexamined Publication No. 51-141801). However, in the aforementioned method, an alcohol as a starting material cannot be completely converted into a corresponding carbonyl compound, which arises a problem from a viewpoint of a reaction yield.
A process is also reported in which rather inexpensive aluminum alkoxide is used in a catalytic amount and a tert-aldehyde is used as a hydride acceptor (U.S. Pat. No. 4,663,488). However, industrial application of said method is limited from a viewpoint of a price of the hydride acceptor.
Furthermore, a method is reported in which diisopropoxyaluminum trifluoroacetate, prepared by adding trifluoroacetic acid to aluminum isopropoxide, is used as a catalyst and p-nitrobenzaldehyde is used as a hydride acceptor (K. G. Akamanchi, et al., Tetrahedron Lett. 1997, 38, 6925). However, this method utilizes a stoichiometric amount of the catalyst, and oxidation of allyl alcohols is neither taught nor suggested in the report.
DISCLOSURE OF THE INVENTION
An object of the present invention is to solve the aforementioned problems and to provide a method for oxidation of allyl alcohols to corresponding aldehydes or ketones which is industrially advantageous.
Under the circumstances, the inventors of the present invention conducted various researches to find an industrially advantageous method for oxidation of allyl alcohols to corresponding aldehydes or ketones, i.e., a method utilizing an inexpensive aluminum alkoxide and a hydride acceptor. As a result, they found a novel method for oxidation of allyl alcohols and thus achieved the present invention.
The present invention thus provides a method for producing an aldehyde or a ketone represented by the following general formula [I]:
wherein R
1
represent hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 11 carbon atoms, R
2
represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or an aryl group having 6 to 10 carbon atoms. R
3
and R
4
independently represent hydrogen atom, and wherein R
1
and R
4
may bind to each other to form an alkylene ring having 1 to 5 carbon atoms and/or R
2
and R
3
may bind to each other to form an alkylene ring having 1 to 6 carbon atoms, which comprises a step of reacting an allyl alcohol represented by the following general formula [II]:
wherein R
1
, R
2
, R
3
and R
4
have the same meanings as those defined above with a hydride acceptor represented by the following general formula [III]:
wherein X and Y independently represent hydrogen atom, a halogen atom, or nitro group, provided that said hydride acceptor wherein both of X and Y are simultaneously represent hydrogen atoms is excluded, in the presence of an aluminium alkoxide as an Oppenauer oxidation catalyst.
According to preferred embodiments of the present invention, provided are:
the aforementioned method wherein, in the allyl alcohol represented by the general formula [II], R
1
represents hydrogen atom or methyl group, R
2
represents phenyl group or a group represented by the following general formula [IV]:
wherein m represents an integer of from 1 to 3 and
- - - -
represents a single bond or a double bond, and each of R
3
and R
4
represents hydrogen atom, or wherein, in the allyl alcohol represented by the general formula [II], R
1
represents a group represented by the general formula [IV], R
2
represents hydrogen atom or methyl group, and each of R
3
and R
4
represents hydrogen atom;
the aforementioned method, wherein the allyl alcohol represented by the general formula [II] is (2E,6E)-3,7,11-trimethyl-2,6,10-dodecatrien-1-ol;
the aforementioned method, wherein the hydride acceptor represented by the general formula [III] is a hydride acceptor selected from 3-nitrobenzaldehyde, 2-nitrobenzaldehyde, 2-fluorobenzaldehyde and 2-bromobenzaldehyde;
the aforementioned method, wherein the hydride acceptor represented by the general formula [III] is 2-nitrobenzaldehyde
the aforementioned method, wherein the Oppenauer oxidation catalyst is selected from aluminum isopropoxide, aluminum tert-butoxide, aluminum phenoxide, and aluminum sec-butoxide; and
the aforementioned method, wherein the Oppenauer oxidation catalyst is aluminum isopropoxide.
By the method of the present invention, allyl alcohols can be converted to corresponding aldehydes or ketones in a high yield under a mild condition using an inexpensive catalyst and a hydride acceptor. Therefore, the aforementioned method of the present invention has industrial advantages.
BEST MODE FOR CARRYING OUT THE INVENTION
In the aforementioned formulas, R
1
, R
2
, R
3
and R
4
represent hydrogen atom or a hydrocarbonic group. Examples of the hydrocarbonic group include, for example, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group and the like. Preferred alkyl groups are those having 1 to 6 carbon atoms, preferred alkenyl groups are those having 2 to 16 carbon atoms, and they may be linear or branched. Preferred aryl groups are those having 6 to 10 carbon atoms.
Examples of the alkyl group include, but not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2-ethylbutyl, 1-ethylbutyl, 1,3-dimethylbutyl and the like.
Examples of the alkenyl group include, but not limited to, vinyl, 1-propenyl, 2-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 2-methyl-2-butenyl, 1-pentenyl, 1-hexenyl, hexadienyl, heptenyl and the like.
Examples of the alkynyl group include, but not limited to, et
Komatsu Toshiya
Matsubayashi Sou
Tanikawa Michika
Tanikawa Shin
Greenblum & Bernstein P.L.C.
Nikken Chemicals Co., Ltd.
Richter Johann
Witherspoon Sikarl A.
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