Gojko Lalic

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Name: Lalic, Gojko

Organization: University of Washington , USA

Department: Department of Chemistry

Title: Assistant(PhD)

TOPICS

Organic Chemistry

Fluorination Amination Metal Hydride

Chemicals
References

Catalytic Anti-Markovnikov Hydroallylation of Terminal and Functionalized Internal Alkynes: Synthesis of Skipped Dienes and Trisubstituted Alkenes

Co-reporter:Melrose Mailig, Avijit Hazra, Megan K. Armstrong, and Gojko Lalic

Journal of the American Chemical Society May 24, 2017 Volume 139(Issue 20) pp:6969-6969

Publication Date(Web):April 28, 2017

DOI:10.1021/jacs.7b02104

We have developed catalytic anti-Markovnikov hydroallylation of terminal and functionalized internal alkynes. In this article, we describe the development of the reaction, exploration of the substrate scope, and a study of the reaction mechanism. Synthesis of skipped dienes through the hydroallylation of terminal alkyl and aryl alkynes with simple allyl phosphates and 2-substituted allyl phosphates is described. The hydroallylation of functionalized internal alkynes leads to the formation of skipped dienes containing trisubstituted alkenes. We demonstrate that the hydroallylation of internal alkynes can be used in the regio- and diastereoselective synthesis of complex trisubstituted alkenes. A mechanism of the hydroallylation reaction is proposed, and experimental evidence is provided for the key steps of the catalytic cycle. Stoichiometric experiments demonstrate an unexpected role of lithium alkoxide in the carbon–carbon bond-forming step of the reaction. A study of the hydrocupration of internal alkynes provides new insight into the structure, stability, and reactivity of alkenyl copper intermediates, as well as insight into the source of the regioselectivity in reactions of internal alkynes.

Catalytic Hydroalkylation of Allenes

Co-reporter:Mitchell Lee;Mary Nguyen;Chance Brt;Werner Kaminsky

Angewandte Chemie International Edition 2017 Volume 56(Issue 49) pp:15703-15707

Publication Date(Web):2017/12/04

DOI:10.1002/anie.201709144

AbstractWe have developed a catalytic method for the hydroalkylation of allenes using alkyl triflates as electrophiles and silane as a hydride source. The reaction has an excellent substrate scope and is compatible with a wide range of functional groups, including esters, aryl halides, aryl boronic esters, sulfonamides, alkyl tosylates, and alkyl bromides. We found evidence for a reaction mechanism that involves unusual dinuclear copper ally complexes as catalytic intermediates. The unusual structure of these complexes provides a rationale for their unexpected reactivity.

Catalytic Hydroalkylation of Allenes

Co-reporter:Mitchell Lee;Mary Nguyen;Chance Brt;Werner Kaminsky

Angewandte Chemie 2017 Volume 129(Issue 49) pp:15909-15913

Publication Date(Web):2017/12/04

DOI:10.1002/ange.201709144

Coinage Metal Hydrides: Synthesis, Characterization, and Reactivity

Co-reporter:Abraham J. Jordan, Gojko Lalic, and Joseph P. Sadighi

Chemical Reviews 2016 Volume 116(Issue 15) pp:8318-8372

Publication Date(Web):July 25, 2016

DOI:10.1021/acs.chemrev.6b00366

Hydride complexes of copper, silver, and gold encompass a broad array of structures, and their distinctive reactivity has enabled dramatic recent advances in synthesis and catalysis. This Review summarizes the synthesis, characterization, and key stoichiometric reactions of isolable or observable coinage metal hydrides. It discusses catalytic processes in which coinage metal hydrides are known or probable intermediates, and presents mechanistic studies of selected catalytic reactions. The purpose of this Review is to convey how developments in coinage metal hydride chemistry have led to new organic transformations, and how developments in catalysis have in turn inspired the synthesis of reactive new complexes.

Catalytic activation of a single C–F bond in trifluoromethyl arenes

Co-reporter:Hester Dang, Aaron M. Whittaker and Gojko Lalic

Chemical Science 2016 vol. 7(Issue 1) pp:505-509

Publication Date(Web):23 Oct 2015

DOI:10.1039/C5SC03415A

Synthetic methods for the direct transformation of ArCF3 to ArCF2R would enable efficient diversification of trifluoromethyl arenes and would be of great utility in medicinal chemistry. Unfortunately, the development of such methods has been hampered by the fundamental properties of C–F bonds, which are exceptionally strong and become stronger with increased fluorination of the carbon atom. Here, we describe a method for the catalytic reduction of ArCF3 to ArCF2H through a highly selective activation of a single C–F bond. Mechanistic studies reveal separate reaction pathways for the formation of ArCF2H and ArCH3 products and point to the formation of an unexpected intermediate as the source of the unusual selectivity for the mono-reduction.

Mechanism of Copper-Catalyzed Hydroalkylation of Alkynes: An Unexpected Role of Dinuclear Copper Complexes

Co-reporter:Alison M. Suess; Mycah R. Uehling; Werner Kaminsky

Journal of the American Chemical Society 2015 Volume 137(Issue 24) pp:7747-7753

Publication Date(Web):June 4, 2015

DOI:10.1021/jacs.5b03086

This article describes a mechanistic study of copper-catalyzed hydroalkylation of terminal alkynes. Relying on the established chemistry of N-heterocyclic carbene copper hydride (NHCCuH) complexes, we previously proposed that the hydroalkylation reaction proceeds by hydrocupration of an alkyne by NHCCuH followed by alkylation of the resulting alkenylcopper intermediate by an alkyl triflate. NHCCuH is regenerated from NHCCuOTf through substitution with CsF followed by transmetalation with silane. According to this proposal, NHCCuH must react with an alkyne faster than with an alkyl triflate to avoid reduction of the alkyl triflate. However, we have determined that NHCCuH reacts with alkyl triflates significantly faster than with terminal alkynes, strongly suggesting that the previously proposed mechanism is incorrect. Additionally, we have found that NHCCuOTf rapidly traps NHCCuX (X = F, H, alkenyl) complexes to produce (NHCCu)2(μ-X)(OTf) (X = F, H, alkenyl) complexes. In this article, we propose a new mechanism for hydroalkylation of alkynes that features dinuclear (NHCCu)2(μ-H)(OTf) (X = F, H, alkenyl) complexes as key catalytic intermediates. The results of our study establish feasible pathways for the formation of these intermediates, their ability to participate in the elementary steps of the proposed catalytic cycle, and their ability to serve as competent catalysts in the hydroalkylation reaction. We also provide evidence that the unusual reactivity of the dinuclear complexes is responsible for efficient hydroalkylation of alkynes without concomitant side reactions of the highly reactive alkyl triflates.

Copper-Catalyzed Hydroalkylation of Terminal Alkynes

Co-reporter:Mycah R. Uehling; Alison M. Suess

Journal of the American Chemical Society 2015 Volume 137(Issue 4) pp:1424-1427

Publication Date(Web):January 26, 2015

DOI:10.1021/ja5124368

We have developed a copper-catalyzed hydroalkylation of terminal alkynes using alkyl triflates as coupling partners and (Me2HSi)2O as a hydride donor. The hydroalkylation proceeds with excellent anti-Markovnikov regioselectivity and provides exclusively (E)-alkenes. We have demonstrated that both alkyl- and aryl-substituted alkynes can be used as substrates, together with 1° alkyl and benzylic triflates. Finally, the transformation can be accomplished in the presence of a wide range of functional groups. Overall, the new hydroalkylation reaction allows highly efficient and diastereospecific synthesis of (E)-alkenes from readily available terminal alkynes and alkyl triflates. On the basis of a preliminary mechanistic study, we propose that the hydroalkylation reaction involves copper hydride formation, hydrocupration of an alkyne, and alkylation of an alkenyl copper intermediate.

Practical catalytic method for synthesis of sterically hindered anilines

Co-reporter:Melrose Mailig, Richard P. Rucker and Gojko Lalic

Chemical Communications 2015 vol. 51(Issue 55) pp:11048-11051

Publication Date(Web):03 Jun 2015

DOI:10.1039/C5CC03565A

A practical catalytic method for the synthesis of sterically hindered anilines is described. The amination of aryl and heteroaryl boronic esters is accomplished using a catalyst prepared in situ from commercially available and air-stable copper(I) triflate and diphosphine ligand. For the first time, the method can be applied to the synthesis of both secondary and tertiary anilines in the presence of a wide range of functional groups. Esters, aldehydes, alcohols, aryl halides, ketones, nitriles, and nitro arenes are all compatible with the reaction conditions. Finally, even the most sterically hindered anilines can be successfully prepared under mild reaction conditions. Overall, the new method addresses significant practical limitations of a transformation previously developed in our lab, and provides a valuable complement to the existing methods for the synthesis of anilines.

Catalytic Anti-Markovnikov Hydrobromination of Alkynes

Co-reporter:Mycah R. Uehling ; Richard P. Rucker

Journal of the American Chemical Society 2014 Volume 136(Issue 24) pp:8799-8803

Publication Date(Web):June 4, 2014

DOI:10.1021/ja503944n

We have developed the first catalytic method for anti-Markovnikov hydrobromination of alkynes. The reaction affords terminal E-alkenyl bromides in high yield and with excellent regio- and diastereoselectivity. Both aryl- and alkyl-substituted terminal alkynes can be used as substrates. Furthermore, the reaction conditions are compatible with a wide range of functional groups, including esters, nitriles, epoxides, aryl boronic esters, terminal alkenes, silyl ethers, aryl halides, and alkyl halides. A preliminary study of the reaction mechanism suggests that the hydrobromination reaction involves hydrocupration of an alkyne, followed by the bromination of the alkenyl copper intermediate. This study also suggests that 2-tert-butyl potassium phenoxide functions as a mild catalyst turnover reagent and provides a better understanding of the unique effectiveness of (BrCl2C)2 among brominating reagents.

Copper-Catalyzed Reduction of Alkyl Triflates and Iodides: An Efficient Method for the Deoxygenation of Primary and Secondary Alcohols

Co-reporter:Hester Dang;Nick Cox

Angewandte Chemie International Edition 2014 Volume 53( Issue 3) pp:752-756

Publication Date(Web):

DOI:10.1002/anie.201307697

Abstract

We describe an effective method for catalytic reduction of 1° alkyl sulfonates, and 1° and 2° iodides in the presence of a wide range of functional groups. This Cu-catalyzed reaction provides a means for the effective deoxygenation of alcohols, as demonstrated by the highly selective reduction of 1° alcohols using a triflation/reduction sequence. A preliminary study of the reaction mechanism suggests that the reduction does not involve free-radical intermediates.

Mild Copper-Catalyzed Fluorination of Alkyl Triflates with Potassium Fluoride

Co-reporter:Hester Dang;Melrose Mailig ; Gojko Lalic

Angewandte Chemie International Edition 2014 Volume 53( Issue 25) pp:6473-6476

Publication Date(Web):

DOI:10.1002/anie.201402238

Abstract

A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45 °C using 2 mol % of the copper catalyst. With 10 mol % of the catalyst, full conversion can be achieved in less than 10 minutes at 45 °C, and thus makes this procedure potentially suited for the preparation of ¹⁸F-labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase-transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene).

Copper-Catalyzed Reduction of Alkyl Triflates and Iodides: An Efficient Method for the Deoxygenation of Primary and Secondary Alcohols

Co-reporter:Hester Dang;Nick Cox

Angewandte Chemie 2014 Volume 126( Issue 3) pp:771-775

Publication Date(Web):

DOI:10.1002/ange.201307697

Abstract

Mild Copper-Catalyzed Fluorination of Alkyl Triflates with Potassium Fluoride

Co-reporter:Hester Dang;Melrose Mailig ; Gojko Lalic

Angewandte Chemie 2014 Volume 126( Issue 25) pp:6591-6594

Publication Date(Web):

DOI:10.1002/ange.201402238

Abstract

Monophasic Catalytic System for the Selective Semireduction of Alkynes

Co-reporter:Aaron M Whittaker and Gojko Lalic

Organic Letters 2013 Volume 15(Issue 5) pp:1112-1115

Publication Date(Web):February 21, 2013

DOI:10.1021/ol4001679

A highly efficient semireduction of alkynes has been developed. Using 0.5–2 mol % of a copper catalyst, semireduction can be accomplished with a wide range of substrates, including both internal and terminal alkynes without over-reduction. The new method has excellent chemoselectivity, and the semireduction can be accomplished even in the presence of nitro and aryl iodo groups. Finally, commercial availability of a catalyst precursor adds to the appeal of the new catalytic system.

Catalytic Asymmetric Synthesis of Cyclic Ethers Containing an -Tetrasubstituted Stereocenter

Co-reporter:Nick Cox;Mycah R. Uehling;Karl T. Haelsig

Angewandte Chemie 2013 Volume 125( Issue 18) pp:4978-4982

Publication Date(Web):

DOI:10.1002/ange.201300174

Catalytic Asymmetric Synthesis of Cyclic Ethers Containing an -Tetrasubstituted Stereocenter

Co-reporter:Nick Cox;Mycah R. Uehling;Karl T. Haelsig

Angewandte Chemie International Edition 2013 Volume 52( Issue 18) pp:4878-4882

Publication Date(Web):

DOI:10.1002/anie.201300174

Synthesis of Tertiary Alkyl Amines from Terminal Alkenes: Copper-Catalyzed Amination of Alkyl Boranes

Co-reporter:Richard P. Rucker ; Aaron M. Whittaker ; Hester Dang

Journal of the American Chemical Society 2012 Volume 134(Issue 15) pp:6571-6574

Publication Date(Web):April 2, 2012

DOI:10.1021/ja3023829

A method for highly selective anti-Markovnikov hydroamination of terminal alkenes is reported. The one-pot procedure involves hydroboration of the alkene followed by a novel electrophilic amination of the alkyl borane catalyzed by an NHC–Cu complex. Terminal alkenes are successfully transformed into tertiary alkyl amines in the presence of a variety of functional groups in yields ranging from 80 to 97% with excellent regioselectivity. Results of a preliminary study of the reaction mechanism are also described.

Asymmetric Synthesis of Trisubstituted Allenes: Copper-Catalyzed Alkylation and Arylation of Propargylic Phosphates

Co-reporter:Mycah R. Uehling, Samuel T. Marionni, and Gojko Lalic

Organic Letters 2012 Volume 14(Issue 1) pp:362-365

Publication Date(Web):December 16, 2011

DOI:10.1021/ol2031119

Asymmetric synthesis of trisubstituted allenes is accomplished by copper-catalyzed alkylation and arylation of propargylic phosphates using organoboron nucleophiles. Excellent chirality transfer and regioselectivity, together with good functional group compatibility, were observed in reactions with both alkyl boranes and arylboronic esters.

Synthesis of Hindered Anilines: Copper-Catalyzed Electrophilic Amination of Aryl Boronic Esters

Co-reporter:Richard P. Rucker;Aaron M. Whittaker;Hester Dang ; Gojko Lalic

Angewandte Chemie International Edition 2012 Volume 51( Issue 16) pp:3953-3956

Publication Date(Web):

DOI:10.1002/anie.201200480

Synthesis of Hindered Anilines: Copper-Catalyzed Electrophilic Amination of Aryl Boronic Esters

Co-reporter:Richard P. Rucker;Aaron M. Whittaker;Hester Dang ; Gojko Lalic

Angewandte Chemie 2012 Volume 124( Issue 16) pp:4019-4022

Publication Date(Web):

DOI:10.1002/ange.201200480

Catalytic SN2′-Selective Substitution of Allylic Chlorides With Arylboronic Esters

Co-reporter:Aaron M. Whittaker, Richard P. Rucker and Gojko Lalic

Organic Letters 2010 Volume 12(Issue 14) pp:3216-3218

Publication Date(Web):June 18, 2010

DOI:10.1021/ol101171v

A copper-catalyzed SN2′-selective arylation of allylic chlorides has been achieved using arylboronic esters as nucleophiles. Arylation products were obtained in high yield with a variety of allylic chlorides and arylboronic esters in the presence of a wide range of functional groups. A mechanism is proposed on the basis of the results of stoichiometric experiments and the isolation of the proposed intermediate.

Catalytic activation of a single C–F bond in trifluoromethyl arenes

Co-reporter:Hester Dang, Aaron M. Whittaker and Gojko Lalic

Chemical Science (2010-Present) 2016 - vol. 7(Issue 1) pp:NaN509-509

Publication Date(Web):2015/10/23

DOI:10.1039/C5SC03415A

Practical catalytic method for synthesis of sterically hindered anilines

Co-reporter:Melrose Mailig, Richard P. Rucker and Gojko Lalic

Chemical Communications 2015 - vol. 51(Issue 55) pp:NaN11051-11051

Publication Date(Web):2015/06/03

DOI:10.1039/C5CC03565A