Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-09-23
2001-11-13
Higel, Floyd D. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S630000, C568S632000, C568S939000, C585S419000, C585S425000, C585S426000, C585S428000, C585S429000, C585S442000, C585S457000, C585S466000, C585S467000, C585S522000, C585S660000, C585S661000
Reexamination Certificate
active
06316675
ABSTRACT:
The present invention relates to a novel process for the synthesis of oletins having aromatic substituents using a novel and particularly active palladium-containing catalyst system, optionally in the presence of selectivity-enhancing additives.
In industrial chemistry, oletins having aromatic substituents play an important role, e.g., as starting materials for polymers, sunscreen agents (UV absorbers), fine chemicals and prodrugs.
A known method for the preparation of such olefins is the so-called Heck reaction in which iodo- or bromoaromatics ArX (X=I, Br) and, in rare cases, chloroaromatics (X=Cl) are reacted with oletins in the presence of stoichiometric amounts of a base and catalytic amounts of a palladium compound (F. Heck, “Vinyl Substitutions with organopalladium Intermediates” in Comprehensive Organic Syntheses, Vol. 4, Pergamon Press, Oxford, 1991, p. 833; R. F. Heck, Palladium Reagents in Organic Syntheses, Academic Press, London, 1985; R. F. Heck, Org. React. (N.Y.) 1982, 27, 345; A. de Meijere, F. E. Meier, Angew. Chem. 1994, 106, 2473; J. Tsuji, Palladium Reagents and Catalysts: Innovations in Organic Synthesis, Wiley, Chichester, 1995).
However, the Heck reaction has not been used for industrial application to date (B. Cornils, W. A. Herrmann, Applied Homogeneous Catalysis with Organometallic Compounds, VCH, Weinheim, 1996). This is due to the fact, inter alia, that the reactivity of haloaromatics ArX decreases very fast in the order ArI>ArBr>ArCl. Thus, in the research field, the reactive iodoaromatics are employed usually; for industrial application, however, they are much too expensive or difficult to obtain. The common catalysts and precatalysts, such as palladiumtetrakis(triphenylphosphane) Pd(PPh
3
)
4
or Pd(OAc)
2
in the presence of excess PPh
3
, give significantly lower yields in the case of bromoaromatics while the reactions of the chloroaromatics, which are available in particularly large amounts in the industry, proceed with completely unsatisfactory yields. As a cause thereof, Heck states the formation of tetraarylphosphonium compounds whereby the catalyst is decomposed with the precipitation of elemental Pd powder (R. F. Heck, Org. React. (N.Y.) 1982, 27, 345; C. B. Ziegler, R. F. Heck, J. Org. Chem. 1978, 43, 2941). Indeed, catalytic C—C bond formation processes with inert chloroaromatics, especially in terms of Heck reactions, are considered a special challenge (V. V. Crushin, H. Alper, Chem. Rev. 1994, 94, 1047; B. Cornils, W. A. Herrmann, Applied Homogeneous Catalysis with Organometallic Compounds, VCH, Weinheim, 1996).
The Heck reaction of chlorobenzene with styrene to form trans-stilbene proceeds to 60% when 1 mole % Pd(OAc)
2
is used in the presence of 2 mole % of the ligand 1,4-bis(diisopropylphosphino)butane (Y. Ben-David, M. Portnoy, M. Gozin, D. Milstein, Organometallics 1992, 11, 1995) This is among the best results reported in the literature, but it has not been transferred to electron-deficient olefins, such as acrylates, since the highly nucleophilic phosphane initiates undesired polymerizations. Another particular disadvantage is the fact that relatively large amounts of an expensive (or difficult-to-obtain) ligand which is sensitive to oxidation are required. Further, transfer to other substrates was successful only in single cases. Thus, for example, the reaction of styrene with 4-chlorotoluene proceeds to only 50% (Y. Ben-David, M. Portnoy, M. Gozin, D. Milstein, Organometallics 1992, 11, 1995).
The use of Pd salts, such as Pd(OAc)
2
, in the presence of excess tris(o-tolyl)phosphane P(o-Tol)
3
involves an active catalyst system with which the Heck reaction of bromoaromatics, especially if activated by electron-withdrawing substituents, proceeds with little satisfactory to good yields (20-90%) (A. Spencer, J. Organomet. Chem. 1983, 258, 101; J. Organomet. Chem. 1984, 270, 115; EP 0078768 A1 and EP 0103544 A1). In contrast, activated chloroaromatics react with quite poor yields. At any rate, the tact that P(o-Tol)
3
is an expensive and difficult-to-obtain phosphane is a drawback.
In more recent works, it is reported that certain pallada-cycles prepared from Pd(OAc)
2
and P(o-Tol)
3
are unusually active catalysts in the Heck reaction. Thus, even non-activated bromoaromatics, such as bromobenzene or bromoanisole, could be reacted with n-butyl acrylate to form the corresponding Heck products (94-96%) (W. A. Herrmann, C. Bro&bgr;mer, W. Öfele, C.-P. Reisinger, T. Priermeier, M. Beller, H. Fischer, Angew. Chem. 1995, 107, 1989; DE 4421730 C1 and EP 0725049 A1). However, transfer to chloroaromatics was only partially successful. Only activated chloroaromatics, such as 4-chlorobenzaldehyde, could be reacted with n-butyl acrylate (81%), and only in the presence of a tenfold excess of tetrabutylammonium bromide as an additive. Non-activated chloroaromatics, such as chlorobenzene, 4-chloroanisole or chlorotoluene, could not be made to react. Another disadvantage of all these reactions is the fact that the expensive and difficult-to-obtain tris(o-tolyl)phosphane must be employed in the preparation of the catalyst.
Also, there have been numerous attempts to employ Pd-containing heterogeneous catalysts in the Heck reaction. While the results are altogether acceptable for the use of iodoaromatics, no generally satisfactory solution to the problem exists to date in the case of bromo- or chloroaromatics (V. V. Grushin, A. Alper, Chem. Rev. 1994, 94, 1047). Thus, for example, moderate yields are obtained in the reaction of chlorobenzene with styrene using various supported Pd catalysts, even if a tenfold excess of chlorobenzene is used (M. Julia, M. Duteil, C. Grand, E. Kuntz, Bull. Soc. Chim. Fr. 1973, 2791; K. Kaneda, M. Higuchi, T. Imanaka, J. Mol. Catal. 1990, 63, L33). Undesired side-products include benzene and diphenyl.
Thus, it is clear that there is still an urgent need for simple or readily available palladium catalysts for the Heck reaction of chloro- and bromoaromatics.
The present invention provides a solution to the problems described above since it has surprisingly been found that compounds of the type of the above formula III are readily available using a Heck reaction. As catalysts, there are used common palladiumn(II) salts PdXY or their CH
3
CN, PhCN or PPh
3
complexes, wherein typically X=Y=Cl, Br, I, RCO
2
[R=C
1
-C
22
, CF
3
, CCl
3
, CH
2
N(CH
3
)
2
, C
6
H
5
] or RSO
3
(R=C
1
-C
22
, CF
3
, C
4
F
9
, CCl
3
, C
6
H
5
, p—CH
3
C
6
H
4
), or typically X=Cl, Br, I, RCO
2
(R=C
1
-C
22
, CF
3
, CCl
3
, CH
2
OCH
3
, C
6
H
5
), and typically Y=C
6
H
5
, o—, m—, p—CH
3
C
6
H
4
, o-, m-, p—Cl—C
6
H
4
, o-, m-, p—CHOC
6
H
4
, o-, m-, p—CN—C
6
H
4
, o-, m-, p—NO
2
—C
6
H
4
, o-, m-, p—PhCO—C
6
H
4
, o-, m-, p—F—C
6
H
4
, 1-C
10
H
7
or 2-C
10
H
7
, which are mixed with tetraarylphosphonium salts Ar
1
Ar
2
Ar
3
Ar
4
P
+
Z
−
, wherein Ar
1
, Ar
2
, Ar
3
and Ar
4
represent identical or different aryl residues, typically Ar=C
6
H
5
, o-, m-, p—CH
3
—C
6
H
4
, o-, m-, p—Cl—C
6
H
4
, o-, m-, p—CHO—C
6
H
4
, o-, m-, p—CN—C
6
H
4
, o-, m-, p—NO
2
—C
6
H
4
, o-, m-, p—PhCO—C
6
H
4
, o-, m-, p—F—C
6
H
4
, 1-C
10
H
7
or 2-C
10
H
7
, and Z=Cl, Br, RCO
2
(R=C
1
-C
22
, CF
3
, CCl
3
, C
6
H
5
) or RSO
3
(R=C
1
-C
22
, CF
3
, C
4
F
9
, C
6
H
5
, p—CH
3
C
6
H
4
). Preferably, PdCl
2
, PdCl
2
(CH
3
CN)
2
, Pd(OAc)
2
, C
6
H
5
PdCl or C
6
H
5
PdCl.PPh
3
or their dimeric or oligomeric forms are used in the presence of tetraphenylphosphonium chloride or bromide. The ratio of PdXY to Ar
1
Ar
2
Ar
3
Ar
4
P
+
Z
−
ranges between 1:1 and 1:10, a ratio of 1:6 being preferably selected.
Aprotic dipolar solvents, such as dimethylformamide (DMF) dimethylacetamide (DMA), dimethylsulfoxide, propylene carbonate, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) or 1-methyl-2-pyrrolidinone (NMP), preferably DMF or NMP, are used as the solvents.
Metal salts, such as sodium, potassium, cesium, calcium or magnesium
Lohmer Gunther
Lohmer Renate
Reetz Manfred T.
Higel Floyd D.
Norris & McLaughlin & Marcus
Studiengesellschaft Kohle MBH
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