Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2001-02-26
2001-09-18
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S317000
Reexamination Certificate
active
06291716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to an ortho-alkylation method of an aromatic ketone and, more particularly, to a method for introducing an alkyl moiety to an ortho-position of an aromatic ketone by reacting the ketones with olefins in the presence of an amine catalyst and a transition metal catalyst.
2. Description of Related Art
Until now, the introduction of substituents to aromatic compounds has been carried out depending on ortho and para-directivity of conventional substituents. However, it is difficult to introduce a new substituent to ortho-position of compounds because of their steric hindrance, as it is. Further, in a general organic synthesis, functional groups cannot be selectively attached to the ortho-position of aromatic compounds. Additionally, a Fridel-Craft alkylation of aromatic compounds has the same limitation as described above.
Ortho-alkylation through a homogeneous catalyst reaction was first studied by Professor S. Murai, Japan, wherein alkyl groups were introduced to ortho-position of aromatic ketones by reacting the ketones with a silane group-containing olefins in the presence of a ruthenium catalyst. However, this method suffers from the disadvantages of having high efficiency for only silane-containing olefins, and low efficiency or no reactivity for general alkyl moiety-containing olefins, internal olefins or diene compounds.
BRIEF SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in the prior art and to provide a method for introducing an alkyl moiety to an ortho-position of an aromatic ketone through the reaction of the aromatic ketone with an aliphatic or aromatic alkyl moiety-containing compound.
In accordance with an embodiment of the present invention, there is an ortho-alkylation method of an aromatic ketone, in which an alkyl moiety is introduced to an ortho-position of the aromatic ketone in the presence of a primary amine and a transition metal catalyst, said alkyl moiety compound being sourced from aliphatic or aromatic olefins, internal olefins or diene compounds.
In accordance with another embodiment of the present invention, there is an ortho-alkylation method of an aromatic ketone, in which the aromatic ketone is reacted with a primary amine to produce a ketimine which is then reacted with an aliphatic or aromatic alkyl moiety-containing compound in the presence of a transition metal catalyst to introduce an alkyl moiety to an ortho-position of the ketone, said aliphatic or aromatic alkyl moiety-containing compound being sourced from olefins, internal olefins or diene compounds.
DETAILED DESCRIPTION OF THE INVENTION
Useful as starting materials in the present invention are aromatic ketones such as acetophenone or benzophenone, ketimines resulting from the condensation of the aromatic ketones with a primary amine, and olefins such as an aliphatic and aromatic alkyl-containing olefin, internal olefins in which a double bond is internally contained, or diene compounds having two double bonds.
When aromatic ketones are used as starting materials, a primary amine and a transition metal catalyst are employed together as reaction catalysts. At that time, alkylation is carried out in the presence of the transition metal catalysts as illustrated in the following chemical reaction formula 1.
(wherein, R
1
is an alkyl group, R
2
is an alkyl or alkenyl group and R
3
is an alkyl or aryl group.)
In the case of using ketimine resulting from the condensation of an aromatic ketone with a primary amine as starting materials, only a transition metal catalyst is added to carry out alkylation.
A mechanism for introducing an alkyl moiety to an ortho-position of ketones through the reaction of a ketone or ketimine with olefins is shown in the following reaction formula 2.
(wherein, R
1
is an alkyl group, R
2
is an alkyl or alkenyl group, R
3
is an alkyl or aryl group, and [Rh] is a rhodium monovalent catalyst.)
A transition metal catalyst (eg., rhodium monovalent catalyst) is coordinated to nitrogen in ketimine to cleave an adjacent carbon-hydrogen bond, thereby forming an intermediate of a stable pentagonal ring structure to which olefins are coordinated to produce ketimine having substituted alkyl group at an ortho-position through the hydride-insertion and then the reductive-elimination. Such ketimine is hydrolyzed with water to afford aromatic ketone having a substituted alkyl group at its ortho-position.
Examples of transition metal catalysts suitable for the present invention are selected from the group consisting of rhodium monovalent catalysts such as [Rh(C
8
H
14
)
2
Cl]
2
, rhodium trivalent catalyst such as [RhCl
3
AH
2
O], Wilkins catalysts such as (PPh
3
)
3
RhCl or mixtures thereof. When rhodium monovalent or trivalent catalysts are employed, a phosphine compound, such as triphenyl phosphine (PPh
3
), is preferably added. Primary amines are exemplified by benzylamine, aniline, cyclohexylamine, and tert-butylamine.
It is more efficient that said materials are dissolved in organic solvents, such as toluene, and then reacted. The reaction is preferably conducted at approximately 100-150° C. for 2-4 hours.
REFERENCES:
patent: 5396011 (1995-03-01), Kuhn
patent: 6072073 (2000-06-01), Kawatsura et al.
Chung Kwan Yong
Hong Jun Bae
Jun Chul Ho
Kim Yeon Hee
Harrison & Egbert
Jun Chul Ho
Padmanabhan Sreeni
Witherspoon Sikarl A.
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