Mary Watson

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Organization: University of Delaware

Department: Department of Chemistry and Biochemistry

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TOPICS

Organic Chemistry

Phosphine Ligands

Chemicals
References

Stereospecific, Nickel-Catalyzed Suzuki–Miyaura Cross-Coupling of Allylic Pivalates To Deliver Quaternary Stereocenters

Co-reporter:Kelsey M. Cobb, Javon M. Rabb-Lynch, Megan E. Hoerrner, Alex Manders, Qi Zhou, and Mary P. Watson

Organic Letters August 18, 2017 Volume 19(Issue 16) pp:

Publication Date(Web):August 7, 2017

DOI:10.1021/acs.orglett.7b02063

Recognizing the importance of all-carbon, quaternary stereocenters in complex molecule synthesis, a stereospecific, nickel-catalyzed cross-coupling of allylic pivalates with arylboroxines to deliver products equipped with quaternary stereocenters and internal alkenes was developed. The enantioenriched allylic pivalate starting materials are readily prepared, and a variety of functional groups can be incorporated on both the allylic pivalate and the arylboroxine. Additional advantages include the use of a commercially available and air-stable Ni(II) salt and BISBI ligand, mild reaction conditions, and high yields and ee’s. The observed stereoinversion of this reaction is consistent with an open transition state in the oxidative addition step.

Harnessing Alkyl Amines as Electrophiles for Nickel-Catalyzed Cross Couplings via C–N Bond Activation

Co-reporter:Corey H. Basch, Jennie Liao, Jianyu Xu, Jacob J. Piane, and Mary P. Watson

Journal of the American Chemical Society April 19, 2017 Volume 139(Issue 15) pp:5313-5313

Publication Date(Web):March 30, 2017

DOI:10.1021/jacs.7b02389

We developed a strategy to harness alkyl amines as alkylating agents via C–N bond activation. This Suzuki–Miyaura cross coupling of alkylpyridinium salts, readily formed from primary amines, is the first example of a metal-catalyzed cross coupling via C–N bond activation of an amine with an unactivated alkyl group. This reaction enjoys broad scope and functional group tolerance. Primary and secondary alkyl groups can be installed. Preliminary studies suggest a NiI/NiIII catalytic cycle.

Stereospecific Cross Couplings To Set Benzylic, All-Carbon Quaternary Stereocenters in High Enantiopurity

Co-reporter:Qi Zhou, Kelsey M. Cobb, Tianyu Tan, and Mary P. Watson

Journal of the American Chemical Society 2016 Volume 138(Issue 37) pp:12057-12060

Publication Date(Web):September 9, 2016

DOI:10.1021/jacs.6b08075

Asymmetric preparation of all-carbon quaternary stereocenters is an important goal. Despite advances in formation of highly enantioenriched products with quaternary stereocenters proximal to a functional group, methods to install quaternary stereocenters isolated from functional groups are limited. Transition metal catalysis offers a potential solution, but prior cross couplings are limited to allylic substrates or deliver little to no enantiomeric enrichment. We report a stereospecific, nickel-catalyzed Suzuki–Miyaura arylation of tertiary benzylic acetates to deliver products with diaryl and triaryl quaternary stereocenters in high yields and ee’s. This reaction employs an inexpensive, air-stable Ni(II) salt and commercially available phosphine ligand to transform tertiary alcohol derivatives, which are easily available in exceptional ee, into valuable products with stereoretention.

Accessing Both Retention and Inversion Pathways in Stereospecific, Nickel-Catalyzed Miyaura Borylations of Allylic Pivalates

Co-reporter:Qi Zhou, Harathi D. Srinivas, Songnan Zhang, and Mary P. Watson

Journal of the American Chemical Society 2016 Volume 138(Issue 36) pp:11989-11995

Publication Date(Web):September 2, 2016

DOI:10.1021/jacs.6b07396

We have developed a stereospecific, nickel-catalyzed Miyaura borylation of allylic pivalates, which delivers highly enantioenriched α-stereogenic γ-aryl allylboronates with good yields and regioselectivities. Our complementary sets of conditions enable access to either enantiomer of allylboronate product from a single enantiomer of readily prepared allylic pivalate substrate. Excellent functional group tolerance, yields, regioselectivities, and stereochemical fidelities are observed. The stereochemical switch from stereoretention to stereoinversion largely depends upon solvent and can be explained by competitive pathways for the oxidative addition step. Our mechanistic investigations support a stereoretentive pathway stemming from a directed oxidative addition and a stereoinvertive pathway that is dominant when MeCN blocks coordination of the directing group by binding the nickel catalyst.

Enantioselective, Copper-Catalyzed Alkynylation of Ketimines To Deliver Isoquinolines with α-Diaryl Tetrasubstituted Stereocenters

Co-reporter:Srimoyee Dasgupta, Jixin Liu, Clarissa A. Shoffler, Glenn P. A. Yap, and Mary P. Watson

Organic Letters 2016 Volume 18(Issue 23) pp:6006-6009

Publication Date(Web):November 16, 2016

DOI:10.1021/acs.orglett.6b02787

An enantioselective, copper-catalyzed alkynylation of cyclic α,α-diaryl ketiminium ions has been developed to deliver isoquinoline products with diaryl, tetrasubstituted stereocenters. The success of this reaction relied on identification of Ph-PyBox as the optimal ligand, i-Pr2NEt as the base, and CHCl3 as the solvent. A broad scope and functional group tolerance were observed. Notably, the use of both aryl and silyl acetylenes results in high yields and enantioselectivities. Mechanistic experiments are consistent with a dimeric or higher order catalyst.

Nickel-Catalyzed Borylation of Benzylic Ammonium Salts: Stereospecific Synthesis of Enantioenriched Benzylic Boronates

Co-reporter:Corey H. Basch, Kelsey M. Cobb, and Mary P. Watson

Organic Letters 2016 Volume 18(Issue 1) pp:136-139

Publication Date(Web):December 17, 2015

DOI:10.1021/acs.orglett.5b03455

We have developed a stereospecific, nickel-catalyzed cross-coupling of secondary benzylic ammonium salts and diboronate esters to deliver highly enantioenriched benzylic boronates. This reaction utilizes amine-derived electrophiles, which are readily available in high enantiopurity, and simple, inexpensive nickel catalysts. This reaction has broad scope, enabling synthesis of a variety of secondary benzylic boronates in good yields and excellent ee’s.

Diastereoselective, Zinc-Catalyzed Alkynylation of α-Bromo Oxocarbenium Ions

Co-reporter:Tatsiana Haidzinskaya, Hilary A. Kerchner, Jixin Liu, and Mary P. Watson

Organic Letters 2015 Volume 17(Issue 15) pp:3857-3859

Publication Date(Web):July 21, 2015

DOI:10.1021/acs.orglett.5b01838

We have developed a bromination/alkynylation sequence that enables efficient transformation of simple cyclic enol ethers to difunctionalized products. The success of this strategy relies on a highly diastereselective, zinc-catalyzed addition of terminal alkynes to α-bromo oxocarbenium ions, formed in situ via ionization of acetal precursors. Using this method, trans-α-alkynyl-β-halo pyran and furan derivatives can be prepared with high diastereoselectivity and excellent functional group tolerance.

Enantioselective Copper(I)-Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Co-reporter:Srimoyee Dasgupta;Thomas Rivas ;Dr. Mary P. Watson

Angewandte Chemie 2015 Volume 127( Issue 47) pp:14360-14364

Publication Date(Web):

DOI:10.1002/ange.201507373

Abstract

An enantioselective, copper(I)-catalyzed addition of terminal alkynes to isochroman ketals to set diaryl, tetrasubstituted stereocenters has been developed. The success of this reaction relies on identification of a Cu/PyBox catalyst capable of distinguishing the faces of the diaryl-substituted oxocarbenium ion. This challenging transformation enables efficient conversion of readily available, racemic ketals into high-value enantioenriched isochroman products with fully substituted stereogenic centers. High yields and enantiomeric excesses are observed for various isochroman ketals and an array of alkynes.

Enantioselective Copper(I)-Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters

Co-reporter:Srimoyee Dasgupta;Thomas Rivas ;Dr. Mary P. Watson

Angewandte Chemie International Edition 2015 Volume 54( Issue 47) pp:14154-14158

Publication Date(Web):

DOI:10.1002/anie.201507373

Abstract

Enantioselective Copper-Catalyzed Alkynylation of Benzopyranyl Oxocarbenium Ions

Co-reporter:Harathi D. Srinivas, Prantik Maity, Glenn P. A. Yap, and Mary P. Watson

The Journal of Organic Chemistry 2015 Volume 80(Issue 8) pp:4003-4016

Publication Date(Web):April 7, 2015

DOI:10.1021/acs.joc.5b00364

We have developed highly enantioselective, copper-catalyzed alkynylations of benzopyranyl acetals. By using a copper(I) catalyst equipped with a chiral bis(oxazoline) ligand, high yields and enantioselectivities are achieved in the alkynylation of widely available, racemic isochroman and chromene acetals to deliver α-chiral oxygen heterocycles. This method demonstrates that chiral organometallic nucleophiles can be successfully used in enantioselective additions to oxocarbenium ions.

Enantiospecific, Nickel-Catalyzed Cross-Couplings of Allylic Pivalates and Arylboroxines

Co-reporter:Harathi D. Srinivas, Qi Zhou, and Mary P. Watson

Organic Letters 2014 Volume 16(Issue 13) pp:3596-3599

Publication Date(Web):June 13, 2014

DOI:10.1021/ol5016724

We have developed an enantiospecific, nickel-catalyzed cross-coupling of unsymmetric 1,3-disubstituted allylic pivalates with arylboroxines. The success of this reaction relies on the use of BnPPh2 as a supporting ligand for the nickel(0) catalyst and NaOMe as a base. This method shows excellent functional group tolerance and broad scope in both the allylic pivalate and arylboroxine, enabling the preparation of 1,3-diaryl allylic products in high yields with excellent levels of regioselectivity and stereochemical fidelity.

A general, simple catalyst for enantiospecific cross couplings of benzylic ammonium triflates and boronic acids: no phosphine ligand required

Co-reporter:Danielle M. Shacklady-McAtee, Kelsey M. Roberts, Corey H. Basch, Ye-Geun Song, Mary P. Watson

Tetrahedron 2014 70(27–28) pp: 4257-4263

Publication Date(Web):

DOI:10.1016/j.tet.2014.03.039

Nickel-Catalyzed Cross-Couplings of Benzylic Pivalates with Arylboroxines: Stereospecific Formation of Diarylalkanes and Triarylmethanes

Co-reporter:Qi Zhou ; Harathi D. Srinivas ; Srimoyee Dasgupta ;Mary P. Watson

Journal of the American Chemical Society 2013 Volume 135(Issue 9) pp:3307-3310

Publication Date(Web):February 20, 2013

DOI:10.1021/ja312087x

We have developed a stereospecific nickel-catalyzed cross-coupling of benzylic pivalates with arylboroxines. The success of this reaction relies on the use of Ni(cod)2 as the catalyst and NaOMe as a uniquely effective base. This reaction has broad scope with respect to the arylboroxine and benzylic pivalate, enabling the synthesis of a variety of diarylalkanes and triarylmethanes in good to excellent yields and ee’s.

Nickel-Catalyzed Cross Couplings of Benzylic Ammonium Salts and Boronic Acids: Stereospecific Formation of Diarylethanes via C–N Bond Activation

Co-reporter:Prantik Maity ; Danielle M. Shacklady-McAtee ; Glenn P. A. Yap ; Eric R. Sirianni ;Mary P. Watson

Journal of the American Chemical Society 2012 Volume 135(Issue 1) pp:280-285

Publication Date(Web):December 26, 2012

DOI:10.1021/ja3089422

We have developed a nickel-catalyzed cross coupling of benzylic ammonium triflates with aryl boronic acids to afford diarylmethanes and diarylethanes. This reaction proceeds under mild reaction conditions and with exceptional functional group tolerance. Further, it transforms branched benzylic ammonium salts to diarylethanes with excellent chirality transfer, offering a new strategy for the synthesis of highly enantioenriched diarylethanes from readily available chiral benzylic amines.

Copper-Catalyzed Enantioselective Additions to Oxocarbenium Ions: Alkynylation of Isochroman Acetals

Co-reporter:Prantik Maity ; Harathi D. Srinivas ;Mary P. Watson

Journal of the American Chemical Society 2011 Volume 133(Issue 43) pp:17142-17145

Publication Date(Web):October 11, 2011

DOI:10.1021/ja207585p

We have developed an enantioselective, copper(I)-catalyzed addition of terminal alkynes to racemic isochroman acetals. This method is one of the first transition-metal-catalyzed approaches to enantioselective additions to prochiral oxocarbenium ions. In this reaction, TMSOTf is used to form the oxocarbenium ion in situ under conditions compatible with simultaneous formation of the chiral copper acetylide. By using a bis(oxazoline) ligand, good yields and enantioselectivities are observed for a variety of enantioenriched 1-alkynyl isochromans.

Nickel(0)-Catalyzed Heck Cross-Coupling via Activation of Aryl C–OPiv Bonds

Co-reporter:Andrew R. Ehle ; Qi Zhou ;Mary P. Watson

Organic Letters () pp:

Publication Date(Web):February 15, 2012

DOI:10.1021/ol203322v

Using a Ni(dppf) catalyst generated in situ, Heck cross-coupling of aryl pivalates with a variety of olefin partners has been accomplished. This method represents one of the first examples of a C–C cross-coupling via activation of a strong C–O bond with a nonorganometallic coupling partner. It enables the transformation of phenol-based substrates into styrenyl products without generation of a halogenated byproduct or the use of expensive triflate groups.