George W. Kabalka

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Name: Kabalka, George W.

Organization: The University of Tennessee , USA

Department: Departments of Chemistry and Radiology

Title: (PhD)

TOPICS

Organic Chemistry

Chemicals
References

Synthesis of PEG-supported organotrifluoroborates and their applications in palladium-catalyzed homo-coupling reactions

Co-reporter:Li Yong, Min-Liang Yao, David W. Blevins and George W. Kabalka

Dalton Transactions 2015 vol. 44(Issue 10) pp:4759-4764

Publication Date(Web):02 Feb 2015

DOI:10.1039/C4DT03492A

A general synthetic route to water-soluble PEG-supported organotrifluoroborates has been developed. In the presence of air and catalytic amounts of Pd(OAc)2, the PEG-supported organotrifluoroborates undergo homo-coupling reactions smoothly at room temperature. No additional oxidizing agent, base, or phosphine ligands are required.

Iododemetallation of potassium organotrifluoroborates and tributylarylstannanes using sodium iodide/iron(III) chloride

Co-reporter:David W. Blevins, Min-Liang Yao, Li Yong, George W. Kabalka

Tetrahedron Letters 2015 Volume 56(Issue 23) pp:3130-3132

Publication Date(Web):3 June 2015

DOI:10.1016/j.tetlet.2015.01.010

A combinative iron(III) chloride/sodium iodide system was found to be very efficient for the iododemetallation of both organotrifluoroborates and tributyl(aryl)stannanes. A variety of functional groups tolerate the mild reaction conditions.

Ultrasound induced, copper mediated homocoupling using polymer supported aryltrifluoroborates

Co-reporter:Bryan Musolino, Michael Quinn, Kelly Hall, Vitali Coltuclu, George W. Kabalka

Tetrahedron Letters 2013 Volume 54(Issue 31) pp:4080-4082

Publication Date(Web):31 July 2013

DOI:10.1016/j.tetlet.2013.05.102

Using Dowex polymer supported aryltrifluoroborates, we are able to achieve homocoupling for a variety of compounds. The reactions were completed in 6 h, while producing high yields of the desired products. The reaction proceeds under mild conditions, using ultrasound as the energy source, copper acetate as the metal co-reactant, and aqueous ethanol as solvent.

Dialkynylation of aryl aldehydes using dialkynylboron chlorides: A transition-metal-free route to 1,4-diynes

Co-reporter:Min-Liang Yao, Adam B. Pippin, Zhong-Zhi Wu, Michael P. Quinn, Li Yong, Marepally S. Reddy, George W. Kabalka

Journal of Organometallic Chemistry 2012 s 721–722() pp: 164-166

Publication Date(Web):

DOI:10.1016/j.jorganchem.2012.09.008

Iron trichloride promoted hydrolysis of potassium organotrifluoroborates

Co-reporter:David W. Blevins, Min-Liang Yao, Li Yong, George W. Kabalka

Tetrahedron Letters 2011 Volume 52(Issue 49) pp:6534-6536

Publication Date(Web):7 December 2011

DOI:10.1016/j.tetlet.2011.09.140

In the presence of iron trichloride, the hydrolysis of potassium organotrifluoroborates occurs smoothly at room temperature to afford the corresponding organoboronic acids in good to excellent yields. The hydrolysis is effective for aryltrifluoroborates as well as alkenyl- and alkyl-trifluoroborates.

No-carrier-added radioiodination of triolborates, water-soluble complexes of boronic acids

Co-reporter:Murthy R. Akula;Min-Liang Yao

Journal of Labelled Compounds and Radiopharmaceuticals 2011 Volume 54( Issue 3) pp:132-134

Publication Date(Web):

DOI:10.1002/jlcr.1831

Abstract

A convenient and rapid synthesis of iodine-123 labeled aryl and heteroaryl iodides from water-soluble complexes of aryl- and heteroarylboronic acids has been developed. Copyright © 2010 John Wiley & Sons, Ltd.

Chemoselective Bromodeboronation of Organotrifluoroborates Using Tetrabutylammonium Tribromide: Application in (Z)-Dibromoalkene Syntheses

Co-reporter:Min-Liang Yao, Marepally Srinivasa Reddy, Li Yong, Ingrid Walfish, David W. Blevins and George W. Kabalka

Organic Letters 2010 Volume 12(Issue 4) pp:700-703

Publication Date(Web):January 19, 2010

DOI:10.1021/ol9027144

Tetrabutylammonium tribromide (TBATB) has been found to be a unique bromodeboronation reagent for organotrifluoroborates. When compared to previously reported bromodeboronation methods, the mild and metal-free reaction conditions tolerate a wider range of functional groups. High regio- and chemoselectivity are observed in the presence of both unsaturated carbon−carbon bonds and aldehyde functional groups. An efficient synthetic route to (Z)-dibromoalkenes from terminal alkynes has been developed using the TBATB-mediated bromodeboronation as a key step.

Deoxygenation of benzylic alcohols using chloroboranes

Co-reporter:Min-Liang Yao, Adam B. Pippin, George W. Kabalka

Tetrahedron Letters 2010 Volume 51(Issue 5) pp:853-855

Publication Date(Web):3 February 2010

DOI:10.1016/j.tetlet.2009.12.018

New boron-based methods for deoxygenating benzylic alcohols via the corresponding alkoxides are reported.New boron-based methods for deoxygenating benzylic alcohols via the corresponding alkoxides are reported.

Triolborates: water-soluble complexes of arylboronic acids as precursors to iodoarenes

Co-reporter:Murthy R. Akula, Min-Liang Yao, George W. Kabalka

Tetrahedron Letters 2010 Volume 51(Issue 8) pp:1170-1171

Publication Date(Web):24 February 2010

DOI:10.1016/j.tetlet.2009.12.074

A facile synthesis of aryl and heteroaryl iodides from water-soluble complexes of aryl- and heteroarylboronic acids has been developed.A facile synthesis of iodoarenes from triolboroates, water-soluble complexes of arylboronic acids, has been developed.

Titanium(IV) Halide Mediated Coupling of Alkoxides and Alkynes: An Efficient and Stereoselective Route to Trisubstituted (E)-Alkenyl Halides

Co-reporter:Min-Liang Yao, Travis R. Quick, Zhongzhi Wu, Michael P. Quinn and George W. Kabalka

Organic Letters 2009 Volume 11(Issue 12) pp:2647-2649

Publication Date(Web):May 15, 2009

DOI:10.1021/ol900669t

Alkoxide C−O bond cleavage occurs readily at room temperature in the presence of titanium(IV) halide. Capture of the resultant carbocation by alkynes provides an efficient route to trisubstituted (E)-alkenyl halides with high stereoselectivity.

No-carrier-added radiohalogenations utilizing organoboranes: The synthesis of iodine-123 labeled curcumin

Co-reporter:George W. Kabalka, Min-Liang Yao

Journal of Organometallic Chemistry 2009 694(11) pp: 1638-1641

Publication Date(Web):

DOI:10.1016/j.jorganchem.2008.11.040

Thermal and microwave hydrolysis of organotrifluoroborates mediated by alumina

Co-reporter:George W. Kabalka, Vitali Coltuclu

Tetrahedron Letters 2009 50(46) pp: 6271-6272

Publication Date(Web):

DOI:10.1016/j.tetlet.2009.09.008

Synthesis of diaryl disulfides via the reductive coupling of arylsulfonyl chlorides

Co-reporter:George W. Kabalka, Marepally Srinivasa Reddy, Min-Liang Yao

Tetrahedron Letters 2009 50(52) pp: 7340-7342

Publication Date(Web):

DOI:10.1016/j.tetlet.2009.10.061

Boron trihalide mediated haloallylation of aryl aldehydes: reaction and mechanistic insight

Co-reporter:Min-Liang Yao, Scott Borella, Travis Quick and George Walter Kabalka

Dalton Transactions 2008 (Issue 6) pp:776-778

Publication Date(Web):23 Nov 2007

DOI:10.1039/B715395C

The reaction of aryl aldehydes with allylsilanes in the presence of boron trihalides produces haloallylated products. Mechanistic details are presented.

Synthesis of a series of boronated unnatural cyclic amino acids as potential boron neutron capture therapy agents

Co-reporter:George W. Kabalka;Zhongzhi Wu ;Min-Liang Yao

Applied Organometallic Chemistry 2008 Volume 22( Issue 9) pp:516-522

Publication Date(Web):

DOI:10.1002/aoc.1435

Abstract

New boronated unnatural cyclic amino acids, 1–6, were synthesized for potential use in neutron capture therapy. In order to understand the effect of molecular lipophilicity on the biological activity, different linkers were introduced between the boronic acid and 1-aminocycloalkanecarboxylic acid moieties. The key step in the syntheses was the preparation of a series of alkenyl-substituted cycloalkanones, which were subsequently converted to amino acids via the Bücherer–Strecker reaction. The introduction of the boronic acid function into hydrantoins 19–24 was realized by hydroboration reactions using diisopinocampheylborane (Ipc₂BH). The target boronated amino acids were modeled after 1-aminocyclobutanecarboxylic acid and 1-amino-3-boronocyclopentanecarboxylic acid, which have previously demonstrated high uptake in tumors. Copyright © 2008 John Wiley & Sons, Ltd.

Facile synthesis of N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) for protein labeling

Co-reporter:G. Tang;Wenbin Zeng;Meixiang Yu;G. Kabalka

Journal of Labelled Compounds and Radiopharmaceuticals 2008 Volume 51( Issue 1) pp:68-71

Publication Date(Web):

DOI:10.1002/jlcr.1481

Abstract

An efficient preparation of N-succinimidyl 4-[¹⁸F]fluorobenzoate ([¹⁸F]SFB) based on a convenient three-step, one-pot procedure is described. [¹⁸F]Fluorination of the precursor ethyl 4-(trimethylammonium triflate)benzoate gave ethyl 4-[¹⁸F]fluorobenzoate. Saponification of the ethyl 4-[¹⁸F]fluorobenzoate with aqueous tetrapropylammonium hydroxide yielded the corresponding 4-[¹⁸F]fluorobenzoate salt ([¹⁸F]FBA), which was then treated with N,N,N,N′-tetramethyl-O-(N-succinimidyl)uronium hexafluorophosphate. The purified [¹⁸F]SFB was used for the labeling of Avastin^™ (Bevacizumab) through [¹⁸F]fluorobenzoylation of the Avastin's α-amino groups. The decay-corrected radiochemical yields of [¹⁸F]SFB were as high as 44% (based on [¹⁸F]fluoride (n=10) with a synthesis time of less than 60 min. [¹⁸F]Avastin was produced in decay-corrected radiochemical yields of up to 42% (n=5) within 30 min (based on [¹⁸F]SFB). The radiochemical purities of [¹⁸F]SFB and [¹⁸F]Avastin were greater than 95%. Copyright © 2008 John Wiley & Sons, Ltd.

No-carrier-added radiohalogenations utilizing organoborates

Co-reporter:George W. Kabalka;Arjun R. Mereddy;Ganghua Tang

Journal of Labelled Compounds and Radiopharmaceuticals 2007 Volume 50(Issue 5‐6) pp:446-447

Publication Date(Web):30 JUL 2007

DOI:10.1002/jlcr.1186

Isotope incorporation via organoboranes

Co-reporter:George W. Kabalka

Journal of Labelled Compounds and Radiopharmaceuticals 2007 Volume 50(Issue 9‐10) pp:888-894

Publication Date(Web):25 SEP 2007

DOI:10.1002/jlcr.1426

Organoboranes can be used as precursors to a wide variety of functionally substituted, isotopically labeled compounds. Straightforward boron-based methods for incorporating short-lived and stable isotopes of carbon, nitrogen, oxygen, and the halogens have been developed over a period of 20 years. Application of these methods to biology, agriculture, and medicine has been slowed by the limited availability of boronated precursors containing functional groups appropriate to those fields. The situation has changed markedly with the advent of metal catalyzed boron-based reactions, which now produce a variety of important boronated materials readily available in the laboratory and from commercial sources. This is especially important in the medical and pharmaceutical communities where short-lived isotopes of carbon, nitrogen, and the halogens are demonstrating great value in positron and single photon emission tomographic procedures. Copyright © 2007 John Wiley & Sons, Ltd.

The no-carrier-added synthesis of bromine-76 labeled alkenyl and alkynyl bromides using organotrifluoroborates

Co-reporter:James F. Green;Arjun R. Mereddy

Journal of Labelled Compounds and Radiopharmaceuticals 2006 Volume 49(Issue 1) pp:11-15

Publication Date(Web):22 DEC 2005

DOI:10.1002/jlcr.1025

A straightforward radiobromination procedure has been developed for the construction of radiobrominated alkenyl and alkynyl bromides. The organotrifluoroborates used as the reactive intermediates are unique in that they are quite polar and thus readily separated from the desired products. Copyright © 2005 John Wiley & Sons, Ltd.

Alkenylation of allylic alcohols using alkenylboron dihalides: a formal transition-metal free Suzuki reaction

Co-reporter:George W. Kabalka, Min-Liang Yao, Scott Borella and Zhongzhi Wu

Chemical Communications 2005 (Issue 19) pp:2492-2494

Publication Date(Web):31 Mar 2005

DOI:10.1039/B502026C

Carbon–carbon bond formation via substitution of an allylic hydroxide with stereodefined alkenyl groups using alkenylboron dihalides in the absence of transition metals.

Synthesis of an iodine-123-labeled celecoxib analogue: a potential spect agent

Co-reporter:Arjun R. Mereddy;Hildegard M. Schuller

Journal of Labelled Compounds and Radiopharmaceuticals 2005 Volume 48(Issue 4) pp:295-300

Publication Date(Web):8 FEB 2005

DOI:10.1002/jlcr.923

Celecoxib (4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1yl]-benzenesulfonamide) is an effective inhibitor of the cyclooxygenase-2 (COX-2). The synthesis of a no-carrier-added iodine-123-labeled analogue of celecoxib was accomplished in four steps for potential use in single photon tomography. Copyright © 2005 John Wiley & Sons, Ltd.

A facile synthesis of radioiodinated alkynyl iodides using potassium alkynyltrifluoroborates

Co-reporter:George W. Kabalka;Arjun R. Mereddy

Journal of Labelled Compounds and Radiopharmaceuticals 2005 Volume 48(Issue 5) pp:359-362

Publication Date(Web):7 MAR 2005

DOI:10.1002/jlcr.931

Radioiodinated alkynyl iodides have been synthesized for the first time from the corresponding potassium alkynyltrifluoroborates. High yields of radiochemically pure products are obtained. Copyright © 2005 John Wiley & Sons, Ltd.

Synthesis of a novel boronated 1-aminocyclobutanecarboxylic acid as a potential boron neutron capture therapy agent

Co-reporter:George W. Kabalka;Min-Liang Yao

Applied Organometallic Chemistry 2003 Volume 17(Issue 6-7) pp:

Publication Date(Web):7 MAY 2003

DOI:10.1002/aoc.445

A boronated aminocyclobutanecarboxylic acid was synthesized for potential use in neutron capture therapy. The synthesis involves the preparation of hydroxymethylcyclobutanone ketal, which is then converted to an amino acid using Bucherer–Strecker methodology. The molecule is modeled after the unnatural amino acid, 1-aminocyclobutanecarboxylic acid, which has demonstrated high uptake in brain tumors. Copyright © 2003 John Wiley & Sons, Ltd.

Allylboration of carbonyl compounds in ionic liquids

Co-reporter:George W. Kabalka, Bollu Venkataiah and Bhaskar C. Das

Green Chemistry 2002 vol. 4(Issue 5) pp:472-473

Publication Date(Web):02 Sep 2002

DOI:10.1039/B204178M

Room-temperature ionic liquids are suitable reaction media for the allylboration of carbonyl compounds. A wide variety of aldehydes and ketones react with allyldiisopropoxyborane in butylmethylimidazolium bromide at room temperature to yield homoallyic alcohols.

Potassium fluoride doped alumina: an effective reagent for ester hydrolysis under solvent free conditions

Co-reporter:George W. Kabalka, Lei Wang and Richard M. Pagni

Green Chemistry 2001 vol. 3(Issue 5) pp:261-262

Publication Date(Web):01 Oct 2001

DOI:10.1039/B106423C

A microwave-enhanced hydrolysis of esters utilizing potassium fluoride doped alumina in the absence of solvents has been developed. Carboxylic acids are produced in excellent yields along with the corresponding alcohols.

Suzuki coupling with ligandless palladium and potassium fluoride

Co-reporter:George W. Kabalka, Vasudevan Namboodiri and Lei Wang

Chemical Communications 2001 (Issue 8) pp:775-775

Publication Date(Web):03 Apr 2001

DOI:10.1039/B101470F

A ligandless palladium catalyzed Suzuki coupling reaction is described.

Synthesis of 123I labeled Congo Red via solid phase organic chemistry

Co-reporter:George W. Kabalka;Murthy R. Akula;Vasudevan Namboodiri

Journal of Labelled Compounds and Radiopharmaceuticals 2001 Volume 44(Issue 13) pp:921-929

Publication Date(Web):20 SEP 2001

DOI:10.1002/jlcr.518

Microwave-assisted, solventless Suzuki coupling reactions on palladium-doped alumina

Co-reporter:George W. Kabalka, Richard M. Pagni, Lei Wang, Vasudevan Namboodiri and C. Maxwell Hair

Green Chemistry 2000 vol. 2(Issue 3) pp:120-122

Publication Date(Web):17 May 2000

DOI:10.1039/B001191F

The generation of carbon–carbon bonds forms the backbone of organic synthesis. In recent years, the use of boron-containing precursors in palladium-assisted bond forming reactions (the Suzuki reaction) has gained prominence because of the vast array of functionally substituted boron containing reagents available to the organic chemist. The development of a solventless, microwave-assisted Suzuki reaction utilizing a readily recyclable solid catalyst offers numerous benefits. These include the straightforward recovery of both product and catalyst, conservation of energy through the use of microwave irradiation, simple commercial scale up, and low waste protocols due to the absence of solvents.

Reduction of aldehydes using trialkylboranes in ionic liquids

Co-reporter:George W. Kabalka and Rama R. Malladi

Chemical Communications 2000 (Issue 22) pp:2191-2191

Publication Date(Web):31 Oct 2000

DOI:10.1039/B007190K

Non-aqueous ionic liquids, molten salts, have been found to enhance organoboron mediated reductions of aldehydes.

Synthesis of a water soluble boron neutron capture therapy agent: 1-amino-3-[2-(7-{3-[2-(2-hydroxymethyl-ethoxy)-1-(2-hydroxy-1-hydroxymethyl-ethoxymethyl)ethoxy]propyl}-1,7-di-carba-closo-dodecaboran-1-yl)ethyl]cyclobutanecarboxylic acid

Co-reporter:Bhaskar C Das, George W Kabalka, Rajiv R Srivastava, Weiliang Bao, Sasmita Das, Guisheng Li

Journal of Organometallic Chemistry 2000 Volumes 614–615() pp:255-261

Publication Date(Web):8 December 2000

DOI:10.1016/S0022-328X(00)00630-6

A water soluble boronated amino acid containing a cascade polyol, 1-amino-3-[2-(7-{3-[2-(2-hydroxymethyl-ethoxy)-1-(2-hydroxy-1-hydroxymethyl-ethoxymethyl)ethoxy]propyl}-1,7-di-carba-closo-dodecaboran-1-yl)ethyl]cyclobutanecarboxylic acid, has been developed. The key step in the synthesis is the alkylation of 3-[2-(1,7-dicarba-closo-dodecarboran-1-yl)ethyl]cyclobutanone hemithioketal with toluene-4-sulfonic acid 3-[2-(2-benzyloxy-1-benzyloxymethyl-ethoxy)-1-(2-benzyloxy-1-benzyloxymethyl-ethoxymethyl)ethoxy]propyl ester which gave the required precursor ketone which was then converted to the title amino acid via a Bücherer–Strecker synthesis followed by hydrogenolysis to remove the benzyl protecting groups.

Biological evaluation of boronated unnatural amino acids as new boron carriers

Co-reporter:G.W. Kabalka, M.-L. Yao, S.R. Marepally, S. Chandra

Applied Radiation and Isotopes (July 2009) Volume 67(Issues 7–8) pp:S374-S379

Publication Date(Web):July 2009

DOI:10.1016/j.apradiso.2009.03.104

Synthesis of PEG-supported organotrifluoroborates and their applications in palladium-catalyzed homo-coupling reactions

Co-reporter:Li Yong, Min-Liang Yao, David W. Blevins and George W. Kabalka

Dalton Transactions 2015 - vol. 44(Issue 10) pp:NaN4764-4764

Publication Date(Web):2015/02/02

DOI:10.1039/C4DT03492A

Boron trihalide mediated haloallylation of aryl aldehydes: reaction and mechanistic insight

Co-reporter:Min-Liang Yao, Scott Borella, Travis Quick and George Walter Kabalka

Dalton Transactions 2008(Issue 6) pp:NaN778-778

Publication Date(Web):2007/11/23

DOI:10.1039/B715395C

The reaction of aryl aldehydes with allylsilanes in the presence of boron trihalides produces haloallylated products. Mechanistic details are presented.