Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-03-23
2001-10-30
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S397000, C568S417000
Reexamination Certificate
active
06310259
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkylacetoacetates using transition metal compounds as catalysts, followed by saponification and decarboxylation of the &bgr;-ketoester obtained.
When using the asymmetric diene, isoprene, there are 12 possible telomeric products, taking into account the linkage pattern of isoprene units in the direction of attack of the nucleophile in the 1, or 3 position and the E,Z-isomerism of the internal double bond. This number is potentiated by using a nucleophile with several acid hydrogen atoms.
Of the 12 possible telomeric products, three have the desired head-to-tail linkage pattern analogous to that in naturally occurring products.
Hitherto, processes disclosed in the prior art have only led to products in which a very small percentage of this type of telomer, if any, can be detected. A process for the preparation of octadienyl hydrocarbon chains is known from J. Berger,
J. für prakt. Chem.
327 (1985) 634. Selectivities relating to head-to-tail linkages of <8% are obtained using the route described there.
In G. Hata, J. Org. Chem. 1971 (15), 2116 and Zakharkin et 30 al.,
Zh. Org. Khim.
1988, (24) 2325, no reference is made to the production of compounds with the desired heads-to-tail linkage when using the reaction mentioned.
Compounds of this type, in particular &agr;-geranylacetone, however, are of great importance as key components for the synthesis of vitamin E.
OBJECT OF THE INVENTION
The object of the invention is to provide a process in which this compound and also related compounds are obtained, these having been proven to be valuable intermediates.
SUMMARY OF THE INVENTION
The invention provides a process for preparing 6,10- and 6,9-dimethyl-5,10-undecadienyl-2-ones by telomerizing isoprene with alkyl acetoacetates in the presence of a catalyst system consisting of transition metal compound catalyst and a phosphorus- or arsenic-containing compound cocatalyst, characterized in that the process is performed in the presence of a protic additive of the general formula:
in which:
R
1
, R
2
, R
3
represent an alkyl group with 1 to 9 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, a phenyl, or an arylalkyl group,
X
(−)
represents an inorganic or organic anion, in particular halide or sulfate,
y is 1 or 2
and the &bgr;-ketoester so obtained is saponified and decarboxylated in a manner known per se. The invention provides 6,10-isomers in particular.
DETAILED DESCRIPTION
In the process of the present invention aliphatic carboxylic acids with 1 to 6 carbons, arylsulfonic acids or alkylsulfonic acids can be used in addition to or instead of the protic additives in accordance with formulae (I) or (II).
Organic solvents are optionally used and are not restricted to specific compounds, with the exception of the general principle that they behave in an inert manner, in the sense of a chemical reaction.
Thus, a protonizing effect is not intended, as is the case, for example, with alcohols of the general formula (I) in the present reaction.
The solvents are also used in the form of mixtures, wherein compounds in accordance with formula (I) act simultaneously as protic additives and as solvents. For example, the present process can be performed in the presence of an organic solvent. Aromatic solvents such as benzene, toluene or phenol, and also alkyl-substituted phenols, ketones and aliphatic alcohols, are suitable solvents.
In a specific embodiment, the compound of the Formula (I), optionally mixed with non-protic solvents, is used a solvent.
Alkyl acetoacetates useful in the present invention are those represented by the general formula
in which
R represents a C
1
-C
4
alkyl group, branched or unbranched.
In the present invention, it is preferred that at least two equivalents of isoprene are reacted with one equivalent of an alkyl acetoacetate of formula (III).
The present catalyst system consists of a transition metal from groups 9 and 10 of the Periodic System of Elements (IUPAC 1985) or compounds thereof, and a cocatalyst consisting of a compound of the general formula
A (R
4
R
5
R
6
) (IV)
in which
R
4
, R
5
, R
6
are identical or different and represent an alkyl or alkoxy group with 1 to 8 carbon atoms, branched or unbranched, a cycloalkyl group with 6 to 8 carbon atoms, an aryl group, in particular phenyl, optionally substituted, preferably substituted in the 2-position and/or 5-position with an alkyl group, an arylalkyl group, or hydrogen;
A represents phosphorus or arsenic.
Preferably, at least one of the substituents R
4
, R
5
, R
6
is itself substituted by one of the groups comprising OH, —NR
1
H, NR
1
R
2
H(
+
) or —COOH, wherein R
1
and R
2
are defined in the same way as above.
Phosphorus- or arsenic-containing compounds in accordance with formula (IV) are preferably used as cocatalysts, in which at least one of the substituents represents an alkoxy group, in particular a C
3
group. 1 to 10 equivalents of phosphorus- or arsenic-containing compounds according to Formula IV are used to one equivalent of the transition metal or its ions.
The transition metal catalyst useful in the present process is used in an amount sufficient to provide up to 10
−4
to 1 g atom/l of elemental metal. Examples of transition metal compounds or transition metal ligands useful as catalysts in the present process are acetate, carboxylate, carbonate, borate, citrate, bromide, chloride, iodide, hydroxide, nitrate, sulfate, arylsulfonate, alkylsulfonate, acetylacetonate, palladium bis-benzonitrile or potassium tetrapalladate. A palladium-containing compound is particularly preferred in the present invention.
The reaction of the present invention is optionally performed in the presence of a compound, which acts as a reducing agent for the transition metal. Examples of such reducing agent are sodium borohydride, potassium borohydride, zinc powder or magnesium. In combination with isopropanol as solvent, particularly high selectivities are obtained.
In a specific embodiment of the present invention, the 6,10-dimethyl-5,10-undecadienyl-2-one and 6,9-dimethyl-5,10-undecadienyl-2-one are separated from the reaction mixture.
In these cases, Pd acetate is used as the catalyst. The 3-head-to-tail isomers produced in addition to the selectively prepared &agr;-geranylacetone (1-head-to-tail) is another valuable product of this reaction.
Optionally, it has proven advantageous to perform the process in several phases in order, for example, to be able to separate the catalyst or the product(s) more easily.
The selectivities can be controlled by suitable combinations of temperature, solvent and cocatalyst.
The process of the present invention is performed at a temperature of from 0° C. to 130° C., in particular of from 60°C. to 100° C.
REFERENCES:
patent: 3914289 (1975-10-01), Akutagawa et al.
Hahn Rainer
Huthmacher Klaus
Keim Wilhelm
Kraus Armin
Degussa - AG
Smith , Gambrell & Russell, LLP
Vollano Jean F.
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