Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-04-20
2003-07-01
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C558S377000, C568S316000, C568S628000, C568S642000, C585S406000
Reexamination Certificate
active
06586599
ABSTRACT:
TECHNICAL FIELD
This invention relates to coupling reactions of aryl halides with unsaturated silanes, which can be used for chemical synthesis in the polymer and the fine chemical industry.
BACKGROUND
Metal catalyzed coupling reactions of aryl bromides, aryl iodides, and aryl pseudohalides (e.g., triflates) with various substrates is a general method employed for the formation of C—C bonds. Prior art methods generally cannot employ aryl chlorides as feedstock for these chemical transformations, and require the use of more expensive aryl bromides and aryl iodides. The use of aryl chlorides as chemical feedstock in coupling chemistry has proven difficult but would economically benefit a number of industrial processes. The few prior art methods that can employ aryl chlorides use expensive, air-sensitive phosphine ligands. In addition, phosphine ligands are often difficult to remove from the process product.
Nucleophilic N-heterocyclic carbenes, the imidazoline-2-ylidenes (sometimes commonly called imidazol-2-ylidenes) or so-called “phosphine mimics”, have attracted considerable attention as possible alternatives for the widely used phosphine ligands in homogeneous catalysis. A primary advantage of these ligands is that an excess of the ligand is not required. It appears that these ligands do not dissociate from the metal center, thus preventing aggregation of the catalyst to yield the bulk metal.
THE INVENTION
This invention provides a process for conducting coupling reactions of aryl halides with unsaturated silanes. The catalyst system of the present invention permits the use of aryl chlorides as substrates in these coupling reactions while eliminating the need for phosphine ligands. Furthermore, both electron-donating and electron-withdrawing substituents on the aryl halide or pseudohalide, the silane, or both, in the coupling reaction are well tolerated by the catalyst system of the present invention, and provide the corresponding heterocoupled products in excellent yields.
An embodiment of this invention provides a process which comprises mixing, in a liquid medium, i) at least one strong base; ii) at least one aryl halide or aryl pseudohalide in which all substituents are other than silyl groups, wherein the aryl halide has, directly bonded to the aromatic ring(s), at least one halogen atom selected from the group consisting of a chlorine atom, a bromine atom, and an iodine atom; iii) at least one silane wherein the silicon atom is quaternary, wherein one group bound to the silicon atom is unsaturated at the alpha or beta position, and wherein each of the remaining groups bound to the silicon atom is a saturated hydrocarbyl or saturated hydrocarbyloxy group; iv) at least one metal compound comprising at least one metal atom selected from nickel, palladium, and platinum, wherein the formal oxidation state of the metal is zero or two; and v) at least one N-heterocyclic carbene. The N-heterocyclic carbene is selected from the group consisting of an imidazoline-2-ylidene wherein at least the 1 or the 3 position is substituted by a secondary or tertiary group which has at least three atoms, or a protonated salt thereof; an imidazolidine-2-ylidene wherein at least the 1 or the 3 position is substituted by a secondary or tertiary group which has at least three atoms, or a protonated salt thereof; a bis(imidazoline-2-ylidene) wherein a bridging moiety is bound to one nitrogen atom of each ring, and wherein the remaining two nitrogen atoms are each, independently, substituted by a secondary or tertiary group which has at least three atoms, or a protonated salt thereof; a bis(imidazolidine-2-ylidene) wherein a bridging moiety is bound to one nitrogen atom of each ring, and wherein the remaining two nitrogen atoms are each, independently, substituted by a secondary or tertiary group which has at least three atoms, or a protonated salt thereof; and mixtures of two or more of the foregoing.
Further embodiments and features of this invention will be apparent from the ensuing description and appended claims.
The liquid medium for the processes of this invention can include any of a wide range of solvents, and mixtures of solvents are also usable. The exclusion of water is not necessary, but is preferred. Types of solvents that can be used include hydrocarbons, ethers, amides, ketones, and alcohols. Polar solvents are preferred; ethers are a more preferred solvent type. Ethers that may be used include, for example, diethyl ether, di-n-propyl ether, diisopropyl ether, tert-butyl ethyl ether, diheptyl ether, 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran, methyltetrahydrofuran, glyme (the dimethyl ether of ethylene glycol), diglyme (the dimethyl ether of diethylene glycol), and the like. Cyclic ethers and polyethers are preferred; a highly preferred ether is 1,4-dioxane.
A variety of strong bases can be used in the processes of this invention. Fluoride salts are a preferred group of bases. Preferable counterions for the fluoride anion are alkali metal cations and ammonium cations. When an alkali metal fluoride is used, it can be lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, or cesium fluoride, and is preferably cesium fluoride. It is more preferable to use an ammonium fluoride. Suitable substituents for the ammonium cation include hydrogen atoms and hydrocarbyl groups, whether straight chain, branched, or-cyclic. Preferred hydrocarbyl substituents have from 1 to about 10 carbon atoms. Examples of ammonium fluoride salts that can be used in this invention include, but are not limited to, ammonium fluoride (NH
4
F), trimethylammonium fluoride, tetramethylammonium fluoride, phenyltrimethylammonium fluoride, benzyltrimethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, diisopropylammonium fluoride, isopropylcyclohexylammonium fluoride, tetrabutylammonium fluoride, diisobutylammonium fluoride, cyclopentylammonium fluoride, dicyclohexylammonium fluoride, heptylammonium fluoride, tetraoctylammonium fluoride, dinonylammonium fluoride, n-decylammonium fluoride, and tribenzylammonium fluoride. It is preferred that all four substituents of the ammonium cation are hydrocarbyl groups. Preferred ammonium fluoride salts are tetramethylammonium fluoride, tetrabutylammonium fluoride, and tetraoctylammonium fluoride, especially tetrabutylammonium fluoride. Choice(s) of base will vary with the particular system of aryl halide or pseudohalide and silane involved.
Directly bonded to the aromatic ring(s) of the aryl halide or pseudohalide (i.e., aryl halide or aryl pseudohalide) is at least one halogen atom selected from a chlorine atom, a bromine atom, and an iodine atom, or at least one pseudohalide group. The term “pseudohalide group” includes such groups as p-toluenesulfonate (tosylate), trifluoromethanesulfonate (triflate), methanesulfonate (mesylate), nonaflate (ON
f
), and aryl diazonium salts. (ArN
2
⊕
X
63
, where X
63
is halide, BF
4
63
, etc.). The aryl halide or pseudohalide can have two or more such halogen atoms with an atomic number greater than nine and/or pseudohalide groups, including combinations of halogen atoms and pseudohalide groups. However, when two or more such groups are present, the halogen atoms with an atomic number greater than nine and/or pseudohalide groups should all be different from each other. For example, when two such substituents are present, they may be a chlorine atom and a bromine atom, or an iodine atom and a tosylate group, or etc. It is preferred that there is only one chlorine atom, bromine atom, iodine atom, or pseudohalide group directly bound to the aryl ring of the aryl halide or pseudohalide. Aryl chlorides are more preferred as the aryl halide reactants. To prevent self-reaction, it is preferred that silyl groups are not present on the aryl halide or pseudohalide.
The aryl moiety for the aryl halide or pseudohalide can be homocyclic or heterocyclic. Examples of suitable homocyclic aryl moieties include, but are not limited to, benzene, naphthalene, anthracene, phenanthrene, pyrene, biphenyl, acen
Lee Hon Man
Nolan Steven P.
McKane Joseph K.
Sieberth & Patty L.L.C.
Small Andrea D.
University of New Orleans Research and Technology Foundation
LandOfFree
Catalyzed coupling reactions of aryl halides with silanes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Catalyzed coupling reactions of aryl halides with silanes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Catalyzed coupling reactions of aryl halides with silanes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3006354