Directed Nickel-Catalyzed Oxidative Heck Coupling Enables by a Tailored H2 Acceptor

In collaboration with the Xue and Zhao groups from Nankai University, we describe a mechanistically unusual reaction to effect oxidative coupling of alkenes and arylboronic acids under nickel(0) catalysis, appearing today in a manuscript in Nature Communications. Previously, it has been shown that Ni(0) can oxidative add into alcohol O–H bonds to generate a catalytically active Ni(H)(OR), which is capable of mediating hydroarylation of alkenes. Based on careful tuning of the directing group, ligand, and hydrogen acceptor (an electron-poor alkene), we find that this pathway can be perturbed to instead give oxidative Heck products. The reaction is highly regioselective, even with challenging 1,2-disubstituted alkene substrates. Congrats to all of the authors.

For a link to the manuscript, click here: https://www.nature.com/articles/s41467-019-12949-1

Happy Halloween!

Our talented team of students carved some amazing pumpkins at the Engle Lab’s annual Halloween party! It was a spooky time spent playing video games and eating great food!

Congrats to the Class of 2019!

Huge congratulations to the Class of 2019! The Engle lab is incredibly proud of our recent, PhD, college, and high school graduates, who are moving on to incredible jobs, postdocs, and graduate/undergraduate programs around the world!

Graduate Students (PhD)

Dr. John Gurak, Jr.: Bristol-Myers Squibb Process Chemistry
Dr. Zhen Liu: Caltech (Postdoc, F. Arnold)

Undergrads/Visiting Undergrads

Omar Apolinar (CSUSM): Scripps Research (Ph.D. in Chemistry)
Tim Gallagher (Claremont McKenna): WWU Münster (Fulbright wtih F. Glorius)
Xiaohan Li (Nankai U): UCSB (Ph.D. in Chemistry)
Huiqi Ni (USTC): Scripps Research (Ph.D. in Chemistry)
Hanh Ngyuen (UCSD): Amgen Process Chemistry
Tianhua (Josh) Tang (Nankai U): U of Utah (Ph.D. in Chemistry)

High School Students

Nhi Ngyuen (San Marcos High Schooll): UC Berkeley
Matt Demer (San Diego Unified): UC Davis
Rohan Marsters (High Tech High International): AmeriCorps

Directed Alkene Carboboration and -Silylation Paper – Now Accepted

The latest work from our collaboration with Bristol-Myers Squibb was recently accepted for publication in Angewandte Chemie International Edition. This manuscript described the developments of new methods for Pd(0)-catalyzed alkene 1,2-carboboration and -silylation. Compared to prior art, these methods are much more effective with internal alkenes (including tri- and tetrasubstitued). We even show examples of dearomative 1,2-carboboration of electron-rich heterocycles. Lastly, we identified a chiral directing group that enables control of the absolute configuration of the final products. Congrats to all Engle lab coauthors, Zhen, Hou-Xiang, Jiahao, Xiaohan, and Yang, especially our three undergrad co-authors, Hou-Xiang, Jiaohao, and Xiaohan (now in the Ph.D. program at UCSB). It was awesome teaming up with BMS again for this project — thanks to Ryan and Matt for an awesome collaboration!

For a link to the paper, click here: https://onlinelibrary.wiley.com/doi/10.1002/anie.201910304

Chiral Transient Directing Group Preprint Online

We are excited to share a project many years in the making. For the first time, we have succeeded in using chiral transient directing groups to enhance reactivity, control regioselectivity, and achieve stereoinduction in an intermolecular reductive Heck hydroarylation of alkenes. This transient directing group strategy obviates the directing group installation and removal steps that are common in directed alkene functionalization, representing a positive step forward in efficiency and sustainability. Congrats to all of the Engle lab authors, Luke, Zi-Qi, Van, and Ruohan, as well as our collaborators Tuğçe and Peng from the Liu lab. For a link to the pre-print, click below:

https://chemrxiv.org/articles/A_Transient_Directing_Group_Strategy_Enables_Enantioselective_Reductive_Heck_Hydroarylation_of_Alkenes/9795338