Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-05-26
2001-06-26
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S349000, C568S395000
Reexamination Certificate
active
06252118
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to a method for the preparation of ketones and, more particularly, to a method for preparing novel ketones by use of a transition metal catalyst with the aid of a 2-aminopyridine derivative.
2. Description of the Related Art
Until recently, the introduction of carbonyl, one of the most important organic groups, into organic compounds has been in extensive study for preparing ketones. In one of the most typical methods, aldehyde is reacted to a nucleophilic organic metal compound, such as alkylmagnesium halide, to give bivalent alcohol which is then oxidized into ketone with the aid of various oxidizers. However, this method suffers from several disadvantages; it must pass through many reaction steps and it produces many unnecessary by-products during the reaction steps.
In an effort to avoid these problems, active research has been directed to hydroacylation techniques for preparing ketones directly from olefins and aldehyde. Of them, the preparation from aldehyde and olefins in the presence of a metal catalyst and 2-aminopyridine derivatives is actively studded for its simple feasibility under a mild conditions. According to this method, aldehyde is reacted with 2-aminopyridine to give aldimine which is then reacted with olefin through a metal catalyst, followed by hydrolysis to afford ketone. However, this method is disadvantageous in terms of high production cost and low production yield.
Meanwhile, no methods have been reported for the conversion of one ketone into a different one. In order to synthesize a new ketone from a preexisting one, the alkyl radical attached to the carbonyl group must be removed and substituted by a desired alkyl radical. There have not yet been developed methods for effectively cleaving the single bond between the carbon atom of a carbonyl group and the &agr;-carbon atom.
BRIEF SUMMARY OF THE INVENTION
The thorough and intensive research on the synthesis of ketones, repeated by the present invention aiming to synthesize ketones with high yields and economical favors, resulted in the finding that transition metal catalysts can effectively cleave and link the single bond between the carbon of a carbonyl group and the &agr;-carbon atom with the aid of a 2-aminopyridine derivative.
Therefore, it is an object of the present invention to overcome the above problems encountered in prior art and to provide a method for the preparation of ketone with high economical favor and yield.
In accordance with an embodiment of the present invention, there is provided a method for preparing a ketone, comprising the steps of: preparing a reactant mixture consisting of a ketone containing &bgr;-hydrogen relative to the aldehyde group and a vinyl olefin or internal olefin having an aliphatic or aromatic alkyl moiety as starting materials; and reacting the reactant mixture at approximately 100-180° C. for at least 6 hours in the presence of a rhodium or iridium transition metal catalyst and a 2-aminopyridine derivative.
In accordance with another embodiment of the present invention, there is provided a method for preparing a ketone, comprising the steps of: producing a ketimine through the condensation of a reactant ketone and 2-amino-3-pycoline; coordinating a transition metal catalyst to the pyridine radical of the ketimine to cleave a carbon-carbon bond of the reactant ketone and to subsequently remove a &bgr;-hydrogen to form an olefin; coordinating a substitute, different olefin to the metal of the catalyst to produce a different ketimine; and hydrolyzing the different ketimine with the water resulting from the condensation to recover the amine.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to the synthesis of new ketone compounds from preexisting ketone compounds in the presence of a transition metal catalyst and 2-aminopyridine derivatives as illustrated in the following reaction formula 1:
Useful as a starting material is a ketone which has a hydrogen at the &bgr;-position of the carbonyl group, such as benzyl acetone or 2-butanone. Where &bgr;-hydrogen exists on both sides of the carbonyl group, the alkyl radicals on both sides of the carbonyl group are cleaved and substituted by olefins to give dialkyl ketone.
In the present invention, olefins are used to make new ketone compounds. Almost all vinyl-containing olefins can be used for this purpose. Examples of transition metal catalysts suitable to promote this substitution include Wilkins catalysts such as (PPh
3
)RhCl, rhodium monovalent catalysts such as [Rh(C
8
H
14
)
2
]
2
, and rhodium trivalent catalyst such as [RhCl
3
.H
2
O]. When rhodium trivalent catalysts or [Rh(C
8
H
16
)Cl]
2
is employed, a phosphine compound, such as triphenyl phosphine (PPh
3
), is preferably added together.
In combination with the transition metal catalyst, a 2-aminopyridine derivative is used according to the present invention. Although a variety of 2-aminopyridine derivatives may be used, the most preferable is 2-amino-3-pycoline.
An organic solvent, if not indispensable for the synthesis, is helpful in reducing the time of the reaction. However, the reaction free of organic solvents enjoys advantages of minimizing the number of the reactors required, converting all the used materials, except for the catalysts, into the products so as to obtain high production yields, and reusing the used 2-aminopyridine derivative in its entirety.
In the presence of such catalysts, the reactants are reacted in the reaction mechanism shown in the following chemical reaction formula 2:
As shown in the chemical reaction formula 2, the reaction starts with the formation of ketimine through the condensation of ketone with 2-amino-3-pycoline. The transition metal catalyst is coordinated to the pyridine radical of the formed ketimine to cleave the carbon-carbon bond, resulting in forming an olefin by &bgr;-hydrogen removal. Subsequently, exchanging with the removed olefin, a reactant olefin is newly coordinated to the transition metal to form a new ketimine. This ketimine is hydrolyzed by the water formed in the condensation of the early stage to recover the amine and to produce a new ketone. Herein, the transition metal complex takes part in two reactions: condensation and hydroacylation.
A better understanding of the present invention may be obtained in light of the following examples which are set forth illustrate, but are not to be construed to limit the present invention.
REFERENCES:
Chelation-assisted intermolecular hydroacylation: Direct synthesis of ketone from aldehyde and 1-alkene. Jun et al., J. Org. Chem. 1997, 62, pp. 1200-1201.*
Activation of aldehyde C-H bonds to oxidative addition via formation of 3-methyl-2-aminopyridyl aldimines and related compounds: Rhodium based catalytic hydroacylation. SUGGS, J. Am. Chem. Soc., 1979, 101(2), p. 489.
Jun Chul Ho
Lee Hyuk
Davis Brian J.
Harrison & Egbert
Jun Chul Ho
Richter Johann
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