Tandem Isomerization/Carbonylation Enabled by Low-Valent Tungsten Redox Catalysis – Paper In Press with Nature Chemistry

The final version of our study on site-selective W(0)/W(II)-catalyzed alkene isomerization/carbonylation appears this week in Nature Chemistry. In this method, we take advantage of the ability of tungsten to undergo changes between six- and seven-coordinate geometries during the W(0)/W(II) redox couple. In conjunction with a conformationally flexible bidentate directing auxiliary, selective isomerization to (and subsequent functionalization at) classically disfavored positions can be achieved. Congrats to project lead Tanner and visiting undergrad Ziyang (Nick); our collaborators at the University of Pittsburgh, Will, Yu, and Peng; our resident analytical wizard Jason from the Scripps ASF, and crystallographer extraordinaire Milan from UCSD.

For a link to the final version of the paper in Nature Chemistry, click here: https://www.nature.com/articles/s41557-022-00951-y

As a reminder, a pre-print of the paper was deposited in ChemRxiv back in April 2021: https://chemrxiv.org/engage/chemrxiv/article-details/60c757089abda23076f8e61a

(CAAC)Copper-catalyzed three-component carboboration of alkynes – Final version published in ACS Catalysis

The final version of our collaborative study with the Grotjahn lab at SDSU and the Bertrand lab at UCSD has been accepted for publication in ACS Catalysis and appears online this week. We find that under (CAAC)Cu catalysis (CAAC = cyclic (alkyl)(amino)carbene), three-component carboboration of terminal alkynes takes place to furnish branched alkenyl boron compounds with high levels of regioselectivity. Building on our prior findings, we show the CAAC ligands can override substrate control factors and dictate regioselectivity of borylcupration with various carbon electrophiles, including alkyl iodides and allyl alcohol derivatives. Congrats to the entire project team: Yang, Nana, Skyler, Mingyu, and Aaron from our lab; Sima and Doug from SDSU, and Rudy and Guy from UCSD.

For a link to the paper in ACS Catalysis, see: https://pubs.acs.org/doi/full/10.1021/acscatal.2c00614

As a reminder, a pre-print of the paper was deposited in ChemRxiv in February: https://chemrxiv.org/engage/chemrxiv/article-details/61f8b9da360c842812b1d6c2

Luke successfully defends his thesis

Congrats to Luke Oxtoby, who successfully defended his thesis this week, becoming the eighth Ph.D. graduate from the Engle lab. Luke’s research addressed an important problem by establishing the use of (co-catalytic) transient directing groups in palladium-catalyzed alkene functionalization. Next month, Luke will begin a position as a process chemist at Sterling Pharma Solutions in Germantown, Wisconsin. Congratulations Dr. Oxtoby!

Nickel-Catalyzed Alkene 1,2-Alkylsulfenylation Method Published in Chemical Science

The final version of our paper describing the directed, nickel-catalyzed syn-1,2-alkylsulfenylation of unactivated alkenes has been accepted for publication in Chemical Science and appears online this week. Building upon our earlier study on carbosulfenylation, this method accommodates C(sp3) nucleophiles for the first time, allowing for simultaneous C(sp3)–S and C(sp3)–C(sp3) bond formation . Congrats to graduate students Zi-Qi and Hui-Qi, as well as our undergraduate intern Wen-Ji.

For a link to the paper in Chemical Science, click here: https://pubs.rsc.org/en/content/articlelanding/2022/sc/d2sc01563c

As a reminder, a pre-print of the paper was deposited in ChemRxiv in March: https://chemrxiv.org/engage/chemrxiv/article-details/6233b0c08ab3732b56687bad

1,2-Carbofluorination of unactivated alkenes enabled by a sterically tuned auxiliary design – Pre-print now online

In the latest story arising from our lab’s Bristol Myers Squibb collaboration, we report the design of a sterically tuned directing auxiliary, picolinyl-α,α-gem-diethyl amine (PDE), which promotes C(sp3)–F reductive elimination from a Pd(IV) intermediate and enables efficient syn-1,2-carbofluorination of unactivated alkenes under Pd(II)/Pd(IV) catalysis. The improved yield of PDE versus classical directing auxiliaries, such as 8-aminoquinoline (AQ) and 2-(pyridin-2-yl)isopropyl (PIP) is rationalized by comparison of % buried volume (%VBur) across the three pre-reductive-elimination intermediates. Great work by Zhonglin, Luke, Zi-Qi, and Nana on the Scripps side and Geraint from BMS Discovery Chemistry.

For a link to the pre-print in ChemRxiv, click here: https://chemrxiv.org/engage/chemrxiv/article-details/62608592d048ed03304b657d

Selective C(alkenyl)–H Activation Enabled by a Transient Directing Group – Manuscript In Press in Angew. Chem. Int. Ed.

The final version of our collaborative study with the laboratory of Prof. Peng Liu on site-selective palladium(II)-catalyzed C(alkenyl)–H activation enabled by a transient directing group (TDG) appears online today in Angewandte Chemie International Edition. This project continues our research program in developing alkene functionalization reactions that take advantage of reversible attachment of a catalytic mediator (i.e., a TDG). In this work, we show that the presence of a tailored carboxylic acid co-catalyst in conjunction with an amino acid TDG enables C(alkenyl)–H activtion via an exo-palladacycle intermediate. We develop an atropselective method that enables access to axially chiral substituted 1,3-dienes, synthesize alkenyl palladacycle model complexes, and examine the reaction mechanism through DFT. Congrats to Mingyu, Juntao, Tugce, Hui-Qi, and Raul for a great paper!

For a link to the paper, click here: https://onlinelibrary.wiley.com/doi/10.1002/anie.202203624

As a reminder, a pre-print of the paper was deposited in ChemRxiv in March: https://chemrxiv.org/engage/chemrxiv/article-details/622412c997f2109450fec97a

Skyler is awarded an NSF MPS-Acsend Postdoc Fellowship

Congrats to Dr. Skyler Mendoza who has received a National Science Foundation Mathematical and Physical Sciences Ascending Postdoctoral Research Fellowship (NSF MPS-Ascend) to support his work developing dual catalytic fragment insertion methods as well as various outreach activities in San Diego County. Prior to joining the Engle lab in November 2021, Skyler received his Ph.D. from Caltech, where his research in the lab of Prof. Sarah Reisman focused on natural products total synthesis and synthetic methods development. Congrats Skyler!

To learn more about the NSF MPS-Ascend Postdoc Fellowship, click here: https://beta.nsf.gov/funding/opportunities/mathematical-and-physical-sciences-ascending-postdoctoral-research

Catalytic syn-Carbosulfenylation Paper Published in J. Am. Chem. Soc.

The final version of our paper describing Ni(I)/Ni(III)-catalyzed carbosulfenylation is online today in the Journal of the American Chemical Society. The method allows conversion of a diverse collection of widely available alkenes bearing native directing groups to structurally complex organosulfide products, with reactivity and selectivity emanating from specially tailored N–S electrophiles. The syn-stereoselectivity of the reaction complements classical thiiranium chemistry, which delivers anti-sulfenylfunctionalized products. Congrats to graduate students Zi-Qi and Taeho and former SURF intern Yilin. Great work!

For a link to the paper in J. Am. Chem. Soc., click here: https://pubs.acs.org/doi/full/10.1021/jacs.1c13252

As a reminder, a pre-print of the paper was first deposited back in December 2021: https://chemrxiv.org/engage/chemrxiv/article-details/61a7d3e0f35d4ca9794de71d

Zi-Qi Li is selected for 2022 Corteva Agriscience Chemistry Scholars Symposium

Congrats to G4 student Zi-Qi Li, who has been selected to participate in the inaugural Corteva Agriscience Chemistry Scholars Symposium to be held at Corteva’s Global Headquarters in Indianapolis, IN on May 11-13th, 2022! During the symposium, Zi-Qi and other awardees will present their research, tour Corteva’s facilities, and learn about industrial R&D in the agricultural chemistry industry.