Organoboron derivatives and process for coupling organic...

Details Organoboron derivatives and process for coupling organic... Organoboron derivatives and process for coupling organic...

2001-08-06

2004-03-30

Mullis, Jeffrey (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C568S001000, C568S006000, C564S008000, C585S525000

Reexamination Certificate

active

06713566

ABSTRACT:

The present invention relates to a process for covalently coupling organic compounds, in particular to a process for covalently linking an olefinic or acetylenic compound via an organoboron intermediate to other organic compounds. The invention also relates to a process for preparing the organoboron intermediates.
Processes for forming covalent bonds between olefinic or acetylenic compounds and other organic compounds, both inter- and intra-molecular, are of particular importance to the synthetic organic chemist. Many such reactions are known, each requiring its own special reaction conditions, solvents, catalysts, activating groups etc. Some known types of coupling reactions involving olefinic moieties include the Michael reaction and reactions described in the following references: Transition Metals in the Synthesis of Complex Organic Molecules (L. S. Hegedus, University Science Books, 1994, ISBN 0-935702-28-8); Handbook of Palladium Catalysed Organic Reactions (J. Malleron, J. Fiaud and J. Legros, Academic Press, 1997, ISBN 0-12-466615-9); Palladium Reagents and Catalysts (Innovations in Organic Synthesis by J. Tsuji, John Wiley & Sons, 1995, ISBN 0471-95483-7); and N. Miyuara and A. Suzuki, Chem Rev. 1995, 95, 2457-2483.
Catalysts of palladium, its complexes and its salts are well recognised for activation of C—H bonds towards coupling reactions. In this regard the Heck reaction of an alkene or alkyne with an aryl or vinyl halide in the presence of palladium derivatives has been the subject of intensive study. However commercial development of the Heck reaction has not progressed as rapidly as could have been expected. Other Group 8-11 metal catalysts, such as platinum, have also been used to activate such carbon bonds.
The success of the Heck reaction depends to a large extent on the substrates and the reaction conditions. For example, when two &bgr;-hydrogens are present in the alkene the reaction generally leads to the formation of the (E)-alkenes which are often contaminated with the corresponding (Z)-alkenes.
Although alkene borates (alkenylborates) can be reacted with a variety of organic molecules to give coupled products via the formation of new carbon-carbon bonds (See for example the references above) the process for the preparation of the alkenylborates by the commonly used hydroboration reaction of alkynes is limited because of the difficulties that are encountered through the lack of regiochemistry and/or chemoselectivity (such as the reduction of a number of different functional groups) (See N. Miyuara and A. Suzuki, Chem Rev. 1995, 95, 2457-2483).
Improved and/or alternative methodologies are thus required for the synthesis of organo borates from alkenes and alkynes.
It has now been found that useful organoboron compounds can be synthesised from alkenes and alkynes under mild conditions and in the presence of a range of substituents. This process overcomes or at least alleviates one or more of the limitations encountered in the use of the standard hydroboration methodology. Coupling of the organoboron derivatives with an organic compound may be achieved in the presence of Group 8-11 metal catalyst and a suitable base.
Accordingly the present invention provides a process for covalently coupling organic compounds which comprises reacting an olefinic organic compound having at least one carbon to carbon double bond or an acetylenic compound having at least one carbon to carbon triple bond with a diboron derivative in the presence of a Group 8-11 metal catalyst such that an organoboronate residue is introduced on one or two of the carbon atoms of the respective double or triple bond. In this process the triple bond becomes a double bond, or the double bond becomes a single bond. Other triple or double bonds may be present and, depending on the reaction conditions employed, these may or may not also react with the diboron derivative.
The diboron derivative may be an ester or other stable derivative of diboronic acid. Examples of suitable esters include those of the formula (RO)
2
B—B(OR)
2
where R is optionally substituted alkyl or optionally substituted aryl or —B(OR)
2
represents a cyclic group of formula
where R′ is optionally substituted alkylene, arylene or other divalent group comprising linked aliphatic or aromatic moieties. Preferred diboron derivatives include 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane[bis(pinacolato)diboron or the pinacol ester of diboronic acid], 2,2′-bi-1,3,2-dioxaborolane[bis(ethanediolato)diboron], 2,2′-bi-1,3,2-dioxaborinane[bis(n-propanediolato)diboron], 5,5,5′,5′-tetramethyl-2,2′-bi-1,3,2-dioxaborinane[bis(neopentanediolato)diboron], (4R,4′R,5R,5′R)-tetramethyl-2,2′-bi-1,3,2-dioxaborolane, 1,1,2,2-tetrakis(2-methoxyethyloxy)diborane, bis((1S,2S,3R,5S)-(+)-pinanediolato)diboron(B—B), (4R,4′R)-diphenyl-2,2′-bi-1,3,2-dioxaborolane, (+/−)-4,4′-bi-[(4-methoxyphenoxy)methyl]-2,2′-bi-1,3,2-dioxaborolane, 2,2′-bi-(3aR,7aS)hexahydro-1,3,2-benzodioxaborole, tetraisopropyl (4R,4′R,5R,5′R)-2,2′-bi-1,3,2-dioxaborolane-4,4′5,5′-tetracarboxylate, (3aR,3′aR,6aS,6′aS)-di-tetrahydro-3aH-cyclopenta[d]-2,2′-bi-1,3,2-dioxaborolane, (3R,6S,3′R,6′S)-di-tetrahydrofuro[3,4-d]-2,2′-bi-1,3,2-dioxaborolane, (+/−)-4,4′-bi-(methoxymethyl)-2,2′-bi-1,3,2-dioxaborolane, 2,2′-bi-1,3,2-dioxaborepane, 5,5′-dihydroxymethyl-5,5′-dimethyl-2,2′-bi-1,3,2-dioxaborinane, bis(1R,2R,3S,5R-(−)-pinanediolato)diboron(B—B), 2,2′-bi-4H-1,3,2-benzodioxaborinine, (+/−)4,4′-bi-(phenoxymethyl)-2,2′-1,3,2-dioxaborolane, (+/−)4,4,4′,4 ′,6,6′-hexamethyl-2,2′-bi-1,3,2-dioxaborinane, 5,5,5′,5′-tetraethyl-2,2′-bi-1,3,2-dioxaborinane, 4,4′,5,5′-tetramethyl-2,2′-bi-1,3,2-dioxaborolane, (+/−)-4,4′-dimethyl-2,2′-bi-1,3,2-dioxaborinane, (+/−)-5,5′-dimethyl-2,2′-bi-1,3,2-dioxaborinane, bi-(dinaphtho[2,1-d: 1,2-f])-2,2′-bi-1,3,2-dioxaborepine, 6,6′-diethyl-2,2′-bi-1,3,6,2-dioxazaborocane, 6,6′-dimethyl-2,2′-bi-1,3,6,2-dioxazaborocane, 5,5,5′,5′-tetraphenyl-2,2′-bi-1,3,2-dioxaborinane, 4,4,4′,4′,7,7,7′,7′-octamethyl-2,2′-bi-1,3,2dioxaborepane, 1,1,2,2-tetrakis(neopentyloxy)diborane, (4S,4′S,5S,5′S)-tetramethyl-2,2′-bi-1,3,2-dioxaborolane, tetrabutyl (4R,4′R,5R,5′R)-2,2′-bi-1,3,2-dioxaborolane-4,4′,5,5′-tetracarboxylate, (4R,4′R,5R,5′R)-N4,N4,N4′,N4′,N5,N5,N5′,N5′-octamethyl-2,2′-bi-1,3,2-dioxaborolan e-4,4′,5,5′-tetracarboxamide, 4,4,4′,4′-tetramethyl-2,2′-bi-1,3,2-dioxaborinane. 4,4,4′,4 ′,6,6,6′,6′-octamethyl-2,2′-bi-1,3,2-dioxaborinane, .3,3′-bi-1,5-dihydro-2,4,3-benzodioxaborepine, (+/−)4,4,4′,4′,5,5′-hexamethyl-2,2′-bi-1,3,2-dioxaborolane, 4,4,4′,4′-tetramethyl-2,2′-bi-1,3,2dioxaborolane, 5,5,5′,5′-tetramethyl-2,2′-bi-1,3,2-dioxaborinane, 4,4′,5,5′-tetraphenyl-1,3,2-dioxaborolane, 4,4′-diphenyl-1,3,2-dioxaborolane and 4,4′,6,6′-tetra(tert-butyl)-1,3,2-benxodioxaborole.
Some of the diboron derivatives will be more readily amenable to subsequent hydrolysis than others and may allow for the use of milder reaction conditions. Furthermore, judicious choice of the diboron derivative used may facilitate control over the reaction products formed. The diboron ester derivatives may be made following the method of Brotherton et al. [R. J. Brotherton, A. L. McCloskey, L. L. Peterson and H. Steinberg, J.
Amer. Chem. Soc
. 82, 6242 (196); R. J. Brotherton, A. L. McCloskey, J. L. Boone

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