We have a new undergraduate intern Xiaowei Chen visiting from Rice University. Xiaowei previously worked in the group of Prof. Julian West on ligand-to-metal charge transfer photocatalysis. She joins the lab as an AYRIU scholar and will be working with Anne to explore nickel catalysis. Welcome to the group, Xiaowei!
Appearing online today in Angewandte Chemie International Edition, we describe the most recent findings from our program in dual catalytic enantioselective alkene functionalization via a transient directing group strategy. Specifically, we developed a method for hydroalkenylation and hydroalkynylation of alkenyl aldehydes that is enabled by reversible condensation of tert-leucine. Together with the lab of Prof. Peng Liu at the University of Pittsburgh, we applied density functional theory to elucidate the structural features of the amino acid co-catalyst that lead to high catalytic efficiency and high enantioselectivity. Congrats to the entire project team!
For a link to the paper, click here: https://onlinelibrary.wiley.com/doi/10.1002/anie.202304013
As a reminder, a pre-print of this work in summer 2022: https://chemrxiv.org/engage/chemrxiv/article-details/635875afca86b8d57fc36848
Traditional syntheses of low-valent nickel complexes, such as the archetypal Ni(0) species, Ni(COD)2, require the use stoichiometric quantities of pyrophoric organometallic reductants, such as DIBAL–H, which pose operational and safety complications. In our most recent study, we report a convenient, green, and scalable electroreductive route to Ni(COD)2 as well as other useful low-valent nickel species, including the air-stable Ni(0) precatalyst, Ni(COD)(DQ), that avoids stoichiometric reductants altogether. The method can conveniently performed using the standardized IKA ElectraSyn 2.0 or alternatively in a recirculating flow setup. Congrats to the entire collaborative team: Camille (Engle lab, Scripps Research & Vantourout lab, University of Lyon; Yilin (Engle lab, Scripps Research), Tamara and Gabriele (Baran lab, Scripps Research); Greg and Steve (Bristol Myers Squibb); and Xiangyu (Lin lab, Cornell).
For a link to the pre-print in ChemRxiv, click here: https://chemrxiv.org/engage/chemrxiv/article-details/642b6699a029a26b4cde3e3e
In our latest research publication, Hui-Qi, Por, and collaborators from the Piercey lab at Purdue University and Pfizer, Inc. report a new method for olefin cyclopropanation under Pd(II)/Pd(IV) catalysis. Compared to previous methods, the reaction can directly employ C–H pronucleophiles, such as 1,3-diketones, without the need for activation as a diazo or other carbenoid progenitor. Additionally, with internal alkenes, the reaction provides unusual anti-selective addition due to the underlying directed carbopalladation mechanism. Congrats to the entire team on this collaborative effort.
For a link to the pre-print in ChemRxiv, click here: https://chemrxiv.org/engage/chemrxiv/article-details/641a9863dab08ad68f818947
Congrats to the Engle Lab’s newest doctors Ziqi Li and Taeho Kang!
Ziqi’s Ph.D. focused on the development of a series of regio- and enantioselective hydroarylation reactions. Additionally, she pioneered the development of a collection of reagents and ligand-enabled carbosulfenylation reactions. Ziqi will soon follow in the footsteps of Keary and other Engle Lab alumni starting her postdoc at Caltech. There, she will pursue research in the lab of Prof. Frances Arnold.
Taeho’s Ph.D. work spanned across various research fields in nickel, copper, and palladium chemistry. In particular, his research focused on nickel-catalyzed 1,2-difunctionalization reactions directed by native functional groups such as free alcohols, amines, and carboxylic acids. Taeho will start a position as a joint postdoc in the labs of Prof. Geoffrey Coates and Prof. Yadong Wang at Cornell University.
Together with Prof. Paul Chirik at Princeton and Drs. Eric Simmons and Steve Wisniewski from Bristol Myers Squibb, Keary authored a Perspective in Org. Process Res. Dev. on the importance of academia–industry collaboration in advancing the state of the art in base metal catalysis. The article outlines the various factors that motivate research in base metal catalysis within the pharmaceutical industry and discusses how these challenges can spur innovations reaction, catalyst, and ligand development, such as in the case of our collaborative work on bench-stable Ni(0) pre-catalysts.
For a link to the article, click here: https://pubs.acs.org/doi/10.1021/acs.oprd.3c00025
Today we are pleased to announce publication of a collaborative study with Prof. Yu Lan’s group at Zhengzhou University elucidating the mechanism of nickel-catalyzed conjunctive cross-coupling reactions of alkenes, aryl iodides, and organozinc reagents, which reveals a previously under-appreciated role of the organozinc reagent as a Z-type ligand that facilitates reductive elimination. This revised mechanistic model explains how this type of conjunctive cross-coupling can proceed under such mild conditions without specialized ligand, despite involving a typically challenging C(sp3)–C(sp3) reductive elimination event. Congrats to the entire project team!
For a link to the paper in J. Am. Chem. Soc., click here: https://pubs.acs.org/doi/full/10.1021/jacs.2c09739
In our newest pre-print posted online today, we continue our explorations of reactions enabled by the W0/WII redox manifold and report the discovery of a mild method for selectively isomerizing γ,δ-unsaturated amides into their β,γ-unsaturated counterparts without “over-isomerization” into conjugation. By controlling the ligand environment around the metal center, stereoselectivity can be controlled to favor either the (Z)- or the (E)-isomer. Though organometallic synthesis, we were able to shed light on some details of the reaction mechanism, highlighted by synthesis of a stable WII(π-Allyl)(OAc) complex that can converted in situ to a WII(π-allyl)(H) species, thereby intercepting a proposed intermediate in the catalytic cycle. Congrats to Tanner, Camile, and Raul!
For a link to the pre-print in ChemRxiv, click here: https://chemrxiv.org/engage/chemrxiv/article-details/63bfba1c741025af42ec927c
Congrats to Rancho Bernardo High School senior and Engle lab member, Anna Liu, who was selected today as a 2023 Regeneron Science Talent Search Scholars. Anna is one of only 300 awardees selected from a pool of nearly 2,000 applicants from across the United States. Anna has been a member of the Engle lab since November 2022 and has worked under the mentorship of Taeho Kang. Anna recently earned her first publication in the group (Organometallics 2023, 42, 11). We are so proud of you Anna! Congrats on your achievement!
For more information about the Regeneron STS program and a link the announcement, click here: https://www.societyforscience.org/regeneron-sts/2023-scholars/
Today we report a new strategy for alkene functionalization that can deliver two valuable products in a single step by partnering a mutually enabling oxidative difunctionalization and reductive difunctionalization, a process we term redox-paired alkene functionalization. In the reported reaction system, a single palladium(II) catalyst switches between PdIIX and PdIIAr forms during the catalytic cycle, each of which is active in the respective half-reactions. Specifically, the catalytic cycle achieves oxidative [3+2] annulation with 2-naphthols and reductive 1,2-diarylation with aryl iodides, expanding the scope and utility of both of these transformations. Congrats to all of the co-workers in this collaborative project: Hui-Qi, Tian (May), Shenghua, and Zhen; as well as Malkanthi, who performed computational studies under the joint guidance of Profs. Ken Houk (UCLA) and Peng Liu (Pittsburgh).
For a link to the pre-print in ChemRxiv, click here: https://chemrxiv.org/engage/chemrxiv/article-details/63ad635fff4651a6983afddf
Molecular Complexity through Catalysis 