Organic compounds -- part of the class 532-570 series – Organic compounds – Boron containing
Reexamination Certificate
2002-03-28
2003-11-18
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Boron containing
C568S001000
Reexamination Certificate
active
06649801
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to anionic borate ligands, and bis(phosphino) and (bis(amino) borate ligands in particular. The invention further relates to zwitterionic complexes formed between anionic borate ligands and metals, such complexes finding utility in numerous stoichiometric and catalytic applications.
BACKGROUND OF THE INVENTION
Cationic, coordinatively unsaturated metal centers have played a critical role in the development of organometallic catalysis, and exhibit a wide range of both stoichiometric and catalytic transformations. Such species are frequently generated by methide abstraction with a strong Lewis acid, and they can also be generated by protonation with an acid whose conjugate base is noncoordinating or weakly coordinating.
These cationic metal centers are amongst the most widely studied systems in organometallic research. Industrially important polymerization reactions often undergo key intermediary steps at cationic metal centers. With respect to transformations important to organic synthesis, cationic late metal fragments enjoy widespread use in C—E bond forming processes, where E is C, N, O, S, Si, H, and so forth. Moreover, cationic metal centers are promising candidates for the ultimate goal of selective activation and functionalization of light hydrocarbon substrates.
However, in spite of the advances in the art, there continues to be a need for improved methods of mediating reaction chemistry. The present invention addresses those needs by a unique approach to the chemistry of cationic species whereby charge neutral zwitterions incorporating a partially insulated borate counter-anion are used to mediate reaction chemistry related to their discrete cationic relatives. A review of the use of zwitterions in organometallic chemistry is described in Chauvin et al.,
Eur. J. Inorg. Chem.
577 (2000). Aside from the advantage of eliminating the need for a cocatalyst, there are several significant reactivity differences between the zwitterionic complex of the invention and traditionally cationic systems due to (i) differences in their relative electrophilicities, (ii) differences in donor ligand lability, and (iii) reduced or completely eliminated ion-pairing effects in the zwitterionic systems by comparison to their cationic counterparts. Further, solvents that dissolve ionic compounds almost always have polar, hence coordinating functional groups that can attenuate their reactivity. In principle, the zwitterionic complex of the invention will provide access to the chemistry of cationic metal centers in relatively non-polar hydrocarbon media.
SUMMARY OF THE INVENTION
One aspect of the invention relates to compound having the formula:
wherein: R
1
and R
2
are independently selected from the group consisting of alkyl and aryl; Y is selected from the group consisting of P and N; and R
3
, R
4
, R
5
and R
6
are independently selected from the group consisting of alkyl and aryl.
Another aspect of the invention pertains to a zwitterionic complex of the formula:
wherein: R
1
and R
2
are independently selected from the group consisting of alkyl and aryl; Y is selected from the group consisting of P and N; R
3
, R
4
, R
5
and R
6
are independently selected from the group consisting of alkyl and aryl; Z is a metal; and R
7
and R
8
are independently selected from the group consisting of halo, pseudo-halo, alkyl, aryl and mono or bidentate, displaceable neutral donor ligands.
Another aspect of the invention pertains to a zwitterionic complex of the formula III:
wherein: R
1
and R
2
are independently selected from the group consisting of alkyl and aryl; Y is selected from the group consisting of P and N; R
3
, R
4
, R
5
and R
6
are independently selected from the group consisting of alkyl and aryl; Z is a metal; and R
7
is selected from the group consisting of halo, pseudo-halo, alkyl, aryl and mono or bidentate, displaceable neutral donor ligands.
Yet another aspect of the invention relates to a method of catalyzing a reaction wherein transformation of a robust sigma bond in an organic compound is required, comprising: a) contacting the organic compound with i) an organic or inorganic reagent, and ii) a zwifferionic complex of an anionic borate ligand having the formula:
and a metal compound; wherein: R
1
and R
2
are independently selected from the group consisting of alkyl and aryl; Y is selected from the group consisting of P and N; and R
3
, R
4
, R
5
and R
6
are independently selected from the group consisting of alkyl and aryl; and b) producing an organic compound having a transformed robust sigma bond.
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CA:132:12400 Journal of the American Chemical Society by Peters et al 121(42) pp 9871-9872 1999.*
Journal of the American Chem. Society vol. 123, by Thomas et al pp 5100-5101 2001.*
Bosnich (1998), “Asymmetric Catalysis. A Comparative Study of the Mechanisms of Intramolecular Hydroacylation and Hydrosilation,”Acc. Chem. Res. 31(10):667-674.
Butts et al. (1996), “Syntheses and Structures of Alkyl and Aryl Halide Complexes of the Type [(PiPr3)2PtH(&eegr;1-XR)]BArfand Analogues with Et2O, THF, and H2Ligands. Halide-to Metal &pgr; Bonding in Halocarbon Complexes,”J. Am. Chem. Soc. 118(47):11831-11843.
Chauvin (2000), “Zwitterionic Organometallates,”Eur. J. Inorg. Chem. 577-591.
Drent et al. (1996), “Palladium-Catalyzed Alternating Copolymerization of Alkenes and Carbon Monoxide,”Chem. Rev. 96(2):663-681.
Karsch et al. (1985), “Funtional Trimethylphophine Derivatives. 21. (Phosphinomethyl)aluminum Compounds: Phosphinomethyl-Bridged Dimers and X-ray Structures of [Me2AlCH2PMe2]2and [ClAl(CH2PMe2)2]2,”Organometallics 4(2):231-238.
Lu et al. (2002), “Catalytic Copolymerization of CO and Ethylene with a Charge Neutral Palladium(II) Zwitterion,”J. Am. Chem. Soc. 124(19):5272-5273.
Peters et al. (1998), “Activation of Aromatic C-H Bonds by (dmpe)Pt(Me)X (X=Me, O2CCF3, OTf) Systems,”Organometallics 17(20):4493-4499.
Schlecht et al. (1997), “Trimethylplatinum Triflate: A Versatile Building Block in Coordination Chemistry,”Angew. Chem. Int. Ed. Engl. 36(18):1994-1995.
Stahl et al. (1998), “Homogeneous Oxidation of Alkanes by Electrophilic Late Transition Metals,”Angew. Chem. Int. Edit.37:2181-2192.
Thomas et al. (2001), “Benzene C-H Activation at a Charge Neutral Zwitterionic Platinum(II) Complex,”J. Am. Chem. Soc. 123(21):5100-5101.
Zhong et al. (2002), “C-H Bond Activation by Cationic Platinum(II) Complexes: Ligand Electronic and Steric Effects,”J. Am. Chem. Soc. 124(7):1378-1399.
Betley Theodore A.
Lu Connie
Peters Jonas C.
Thomas John C.
California Institute of Technology
Eberle Shelley P.
Reed & Eberle LLP
Vollano Jean F.
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