Process for the preparation of heteroaryl aldehydes and...

Details Process for the preparation of heteroaryl aldehydes and... Process for the preparation of heteroaryl aldehydes and...

2000-01-05

2001-01-02

Padmanabhan, Sreeni (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S309000, C568S320000, C568S426000

Utility Patent

active

06169213

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of aldehydes and ketones.
2. The Prior Art
Aldehydes and ketones are widely used in organic chemistry. For example, they are important precursors in the synthesis of heterocycles, perfumes and dyestuffs.
A variety of processes are known for the preparation of aldehydes and ketones. For example, the formal and the acyl group are successfully introduced directly into aromatic systems via electrophilic substitution reactions, which, however, are limited by the substitution rules. Aromatic ketones can also be synthesized via organometallic reactions. A disadvantage includes the necessity of using an anhydrous reaction medium. Another disadvantage is the use of toxic chemicals such as phosphorus oxychloride, carbon monoxide, zinc cyanide, mercury organyls and cadmium organyls.
Aldehydes and ketones are frequently prepared via oxidation reactions starting from the corresponding alcohols. An overview is given in the literature reviewed in Houben-Weyl-M{umlaut over (u)}ller, Vol. 7/2a, p. 699 et seq. and Vol. E3, p. 265 et seq., 1983. They are most frequently carried out in nonaqueous medium and often require expensive and/or toxic reagents which are unsuitable for larger-scale syntheses because they are difficult to handle. Aromatic aldehydes and ketones can be prepared from hydroxyalkyl aromatics using stable nitroxide radicals, for example TEMPO, and an oxidant (A. E. J. de Nooy, A. C. Besemer and H. V. Bekkum, Synthesis 1996, 1153). The oxidizing agent here is an oxoammonium ion, which is formed by adding an oxidant. A disadvantage of this method is, on the one hand, the high price of reagents required. A further disadvantage is that a nonaqueous medium is required since otherwise the aldehyde formed oxidizes further to give the carboxylic acid. The formation of aromatic aldehydes from the corresponding hydroxymethyl-aromatics in the presence of the enzyme laccase and ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) was observed by Potthast (Potthast et al., J. Molec. Catal. A: Chemical 1996, 108, and Synth. Commun. 1996, 26, 315). The high price of ABTS, however, excludes applicability of the method on an industrial scale. A further disadvantage is the low selectivity in the presence of methyl and hydroxymethyl groups.
There is therefore a demand for an inexpensive and selective process which satisfies the ever increasing demands in industry and which allows even sensitive aldehydes and ketones to be synthesized on a large scale.
SUMMARY OF THE INVENTION
The invention relates to a process for the preparation of vinyl, alkynyl, aryl or heteroaryl aldehydes or vinyl, alkynyl, aryl or heteroaryl ketones from vinyl-, alkynyl-, aryl- or heteroarylmethanols with the aid of a mediator and an oxidant, wherein the mediator is selected from the group of the aliphatic, cycloaliphatic, heterocyclic or aromatic NO, NOH or
containing compounds.
The vinyl, alkynyl, aryl or heteroaryl aldehydes or vinyl, alkynyl, aryl or heteroaryl ketones are preferably compounds of the formula 1, and the vinyl-, alkynyl-, aryl- or heteroarylmethanols are preferably compounds of the formula 2
where Y
1
and Y
2
can be identical or different and are radicals having up to 20 C atoms and up to 6 rings and at least one of the radicals Y
1
or Y
2
is vinyl, alkynyl, aryl or heteroaryl, and Y
1
and Y
2
may also be part of a ring or of a ring system.
Y
1
is preferably an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or an anthraquinonyl radical, it being possible for the aromatic or heteroaromatic radical Y
1
to be mono- to hexasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C
1
-C
12
-alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or a linear or branched C
1
-C
12
-oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H
2
N— or a linear or branched C
1
-C
12
-N-alkylamino, a linear or branched C
1
-C
12
-N,N-dialkylamino group, NC—, O
2
N—, halogen, HOOC—, HO
3
S—, OHC—, H
2
N—COO—, H
2
N—CO—, H
2
N—CO—NH—, or a linear, branched or cyclic C
1
-C
12
—OCO—, C
1
-C
12
—COO—, C
1
-C
12
—CO—, C
1
-C
12
—NHCO—, C
1
-C
12
—NHCONH—, (C
1
-C
12
)
2
NCO—, C
1
-C
12
—CONH—, or a linear or branched C
1
-C
12
—OSO
2
—, C
1
-C
12
—NH—SO
2
—, or (C
1
-C
12
)
2
N—SO
2
— group, or a phenyl, diphenylmethyl, phenyl-CH═CH—, phenyl-N═N—, phenyl-N═CH—, phenyl-CH═N—, phenoxy, phenyl-NH— phenyl-O—CO—, phenyl-CO—, phenyl-NHCO—, phenyl-CONH—, phenyl-NHCONH—, phenyl-OSO
2
— or phenyl-NH—SO
2
— group whose phenyl radicals can be mono- to pentasubstituted, it being possible for the substituents to be identical or different and to have the meaning of OH, a linear, branched or cyclic C
1
-C
12
-alkyl radical, it being possible for adjacent alkyl groups to form a 5-, 6- or 7-membered ring via a methylene group, or of a linear or branched C
1
-C
12
-oxyalkyl or thioalkyl radical, it being possible for adjacent substituents to form a 5-, 6- or 7-membered ring via a methylene group, a H
2
N— or a linear or branched C
1
-C
12
-N-alkylamino, a linear or branched C
1
-C
12
-N,N-dialkylamino group, NC—, O
2
N—, halogen, HOOC—, HO
3
S—, OHC—, H
2
N—COO—, H
2
N—CO—, H
2
N—CO—NH—, or a linear, branched or cyclic C
1
-C
12
—OCO—, C
1
-C
12
—COO—, C
1
-C
12
CO—, C
1
-C
12
—NHCO—, C
1
-C
12
—NHCONH—, (C
1
-C
12
)
2
NCO—, C
1
-C
12
—CONH—, or of a linear or branched C
1
-C
12
—OSO
2
—, C
1
-C
12
—NH—SO
2
— or (C
1
-C
12
)
2
N—SO
2
— group, or of a phenyl, diphenylmethyl, phenyl-CH═CH—, phenyl-N═N—, phenyl-N═CH—, phenyl-CH═N—, phenoxy, phenyl-NH—, phenyl-O—CO—, phenyl-CO—, phenyl-NHCO—, phenyl-CONH—, phenyl-NHCONH—, phenyl-OSO
2
— or phenyl-NH—SO
2
— group or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and can be hydrogen, linear, branched or cyclic C—C-alkyl radical where one or more methylene groups can be replaced individually by —CHOH, —CO, O—, S—, NH— or by a linear or branched C
1
-C
12
-N-alkylamine radical, or an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or an anthraquinonyl radical, or in which the vinyl group forms part of a ring or ring system.
Y
1
is preferably hydrogen, linear, branched or cyclic C
1
-C
12
-alkyl radical where one or more methylene groups can be replaced individually by —CHOH, —CO, O—, S—, NH— or by a linear or branched C
1
-C
12
-N-alkylamine radical, or an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or anthraquinonyl radical, or an optionally mono- to trisubstituted vinyl radical, or optionally substituted ethynyl radical, in which the substituents can be identical or different and can be hydrogen, linear, branched or cyclic C
1
-C
12
-alkyl radical where one or more methylene groups can be replaced individually by —CHOH, —CO, O—, S—, NH— or by a linear or branched C
1
-C
12
-N-alkylamine radical, or an aromatic or heteroaromatic ring or ring system having up to 6 rings and up to 20 C atoms, whose ring members can be replaced by O, S or N atoms, or an anthraquinonyl radical, or in which the vinyl group forms part of a ring or ring system.
Equally preferred are compounds in which the radicals Y
1
and Y
2
are linked via a methylene group or an ether group or via an amino group which is optionally substituted by a linear, branched or cyclic C
1
-C
12
-alkyl radical.
Especially preferably, Y
1
is a 5-, 6- or 7-membered aromatic or heteroaromatic ring which can be fused to one or two further aromatic rings and whe

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