Xiaohan finishes her six-month internship this week, just in time to return home to spend Chinese New Year with her family. Xiaohan gave an awesome wrap-up talk describing her work on enantioselective directed carboboration of alkenes, and then the lab sent her off in style with a celebratory Korean BBQ lunch. Xiaohan will receive her Bachelor’s degree in chemistry this spring from Nankai University, and she will then return to the US next fall to begin her PhD (exact location still TBD). Thanks for all of your contributions to the lab, Xiaohan! We will miss you!
Today we report our first foray into the enantioselective 1,2-difunctionalization of alkenes, with a new method for palladium(II)-catalyzed asymmetric anti-carboboration. The reaction is promoted by a palladium(II) catalyst and a mono-dentate oxazoline (MOX) ligand. This reaction was found to be stereoconvergent, with both E- and Z-configured alkenes giving the same major diastereomer. Mechanistic studies were performed to shed light on the origin of this phenomenon. A pre-print of this work is available on ChemRxiv (click here). Congrats to the authors, Zhen, Xiaohan, and May, particularly our two undergraduate co-authors Xiaohan and May.
It’s the season of giving and what better way to celebrate the holidays than with non stop outreach opportunities! First, we had the boss young scientists of BEWiSE hosted by Fleet Science come learn about organometallics. Then students from the distant lands of Palm Springs came to help us set things on fire. (This time no evacuation!)
The nickel team strikes again, with a final version of our nickel-catalyzed alkene 1,2-diarylation paper appearing online in final form at J. Am. Chem. Soc. (click here). Through identification of an effective electron-deficient olefin ligand, this catalytic system allow for use of simple commonly encountered primary, secondary, and tertiary amides as directing groups, including those that are native to various target compounds of interest. Additionally, this work represents one of the rare cases in 1,2-diarylation chemistry where an aryl boronic acid derivative can be used as the nucleophilic coupling partner. Congratulations to Joe, Roman, Van, and Malkanthi from the Engle lab and Steve and Martin from Bristol-Myers Squibb. Thanks to everyone involved for a great collaboration. In case anyone missed it, a pre-print of this work was published on ChemRxiv back in early November (click here).
Vincent and Joe’s paper on three-component, nickel-catalyzed umpolung carboamination of alkenyl carbonyl compounds appears online today in final form at ACS Catalysis (click here). This unique transformation enables syn-selective delivery of nitrogen and carbon substituents of choice across an alkene and allows for formation of exceptionally hindered C(sp3)–C and C(sp3)–N bonds. It represents one of the few rare examples in which amine-directed N–O electrophiles (first used in two-component cross-couplings by Johnson) have been integrated into a nickel-mediated alkene functionalization process. It’s a special treat to highlight that the project lead, Vincent (now a grad student upstairs with Ryan Shenvi), performed this work as his senior-year undergrad research project while at UCSD. Props to Joe for great mentorship, and congrats to both authors! In case anyone missed it, a pre-print of this work was published on ChemRxiv back in early November (click here).