Recently, Chair Professor of Chemistry Department Zhang Xumu co-published an article again on the Journal of the American Chemical Society (JACS; Impact Factor: 14.357). Titled “Design and Synthesis of Chiral oxa-Spirocyclic Ligands for Ir-Catalyzed Direct Asymmetric Reduction of Bringmann’s Lactones with Molecular H2,” the paper was first authored by postdoctoral researcher Chen Genqiang and authored by research assistant Lin Bijin, master’s student Huang Jiaming, undergraduate students Zhao Lingyu, Chen Qishu and Jia Shipeng. Zhang Xumu and Associate Professor Yin Qin from SUSTech Academy for Advanced Interdisciplinary Studies are the article’s correspondent authors, with the former leading other authors and forming a research team (Doi: 10.1021/jacs.8b03642).
As the first Chinese Mainland winner of 2002 Arthur C. Cope Scholar Awards and the first entrepreneur from Chinese Mainland who brought biomedical companies to be listed in over-the-counter markets, Professor Zhang Xumu has a classical chemical reaction named after his surname (Zhang enyne cycloisomerization). His research interests are the synthesis of biologically active compounds, material chemistry, and highly efficient and selective catalysis – including transition metal catalyzed asymmetric hydrogenation, asymmetric hydroformylation, and linear hydroformylation. With an h-index of more than 75, Professor Zhang has published over 300 academic papers on Science, JACS, and Angewandte Chemie, which have been cited over 15,000 times. Apart from academia, he has started many research and technology-based companies which have turned significant profits.
Professor Zhang’s team presents a column-free and straightforward synthetic route toward a structurally unique oxaspirocyclic diphenol, termed as O-SPINOL. Features of the synthesis include the construction of the all-carbon quaternary center at an early stage, a critical double intramolecular SNAr step to introduce the spirocycles and the feasibility of operating on >100 g scale. Both enantiomers of O-SPINOL can be easily accessed through optical resolution with L-proline by control of the solvent. The chiral tridentate ligand O-SpiroPAP derived from O-SPINOL has been successfully synthesized and applied in the iridium-catalyzed asymmetric hydrogenation of bridged biaryl lactones under mild reaction conditions, providing valuable and enantioenriched axially chiral molecules in excellent yields and enantioselectivities (up to 99% yield and >99% ee). This method represents a rare example of constructing axially chiral molecules by direct reduction of esters with H2.
To have a further understanding of Professor Zhang Xumu’s research, we set up a face-to-face interview with him and asked a few specific questions.
Q: What’s the most significant breakthrough you’ve made in this research project?
A: We’ve developed a new chiral tridentate ligand called O-SpiroPAP, which could play a significant role in the synthesis of important physiologically active compounds and chiral drugs. Having said that, this breakthrough is more theoretical than practical, contributing to China’s cutting-edge basic scientific research field. Such an area is the source and driving force of research originality, innovation, intelligence, and capital.
Q: What other projects have you done recently?
A: Earlier this year, our team published the article “Asymmetric Synthesis of Chiral Primary Amines by Ruthenium-Catalyzed Direct Reductive Amination of Alkyl Aryl Ketones with Ammonium Salts and Molecular H2” on JACS. In this paper, we have identified a ruthenium/C3-TunePhos catalytic for highly efficient direct reductive amination of simple ketones. The strategy makes use of ammonium acetate as the amine source and H2 as the reductant, which is a user-friendly and operatively simple access to industrially relevant primary amines. We achieved excellent enantio control with a wide range of alkyl aryl ketones and highlighted the practicability of this methodology by scalable synthesis of key intermediates of three drug molecules (J. Am. Chem. Soc. 2018, 140, 2024–2027).
Recently, Nature Communications published “Silicon-oriented regio- and enantioselective rhodium-catalyzed hydroformylation,” whose correspondent authors are Wuhan University’s Associate Professor Lv Hui, my colleague Chung Lung-Wa and I (DOI: 10.1038/s41467-018-04277-7). Hydroformylation of 1,2-disubstituted alkenes usually occurs at the α position of the directing heteroatom such as oxygen atom and nitrogen atom. By contrast, to achieve hydro-formylation on theβ position of the heteroatom is a tough task. Herein, we report the asymmetric rhodium-catalyzed hydroformylation of 1,2-disubstituted alkenylsilanes with excellent regioselectivity at theβposition and enantioselectivity. In a synthetic sense, we achieve the asymmetric hydroformylation on theβposition of the oxygen atom indirectly by using the silicon group as a surrogate for the hydroxyl. Density functional theory calculations are carried out to examine energetics of the whole reaction path for Rh/YanPhos-catalyzed asymmetric hydroformylation and understand its regioselectivity and enantioselectivity. Our computational study suggests that the silicon group can activate the substrate and is critical for the regioselectivity.
To sum up, our team published eight academic papers on eight nature index journals including JACS, ACS Catalysis, Organic Letters and Chemical Communications. Most of the articles center around asymmetric hydrogenation of synthetic drug molecules or biologically active molecules, which have promoted the development application of asymmetric hydroformylation to some extent.
Q: Since you have mentioned research applications, I would like to know your opinion on the social prospects of your team’s findings.
A：As scientists, we always to achieve the best of both worlds: solving complicated academic problems while benefitting the human race. This makes the commercialization of research findings particularly important. It’s like trying to put the books both on the store’s shelves after getting them into the warehouse racks.
There is enormous potential in the industrial application of hydroformylation, take plasticizer for example. Plastic itself is actually very hard, so we need plasticizer to soften the plastics, also known as polyvinyl chloride. Millions of tons of softeners are necessary for China on an annual basis, and the major buyers include Sinopec, PetroChina and China National Offshore Oil Cooperation (CNOOC).
The significance of asymmetric hydrogenation mainly lies in the synthesis of a chiral drug, which accounts for two-thirds of the drugs in the hospital. One of the major problems in the synthesis of bioactive molecules is how to create stereochemical molecules with high efficiency and selectivity. Our teams aim to tackle this problem with cutting-edge theories, methods, and strategies of environmental-friendly drug synthesis. In other words, we will strive to achieve the environmental-friendly synthesis of drugs with catalysts and Intermediates, which will significantly reduce pollution and increase the profits of pharmaceutical companies. At the same time, the achievement can bring down the price of expensive drugs, which is excellent news for patients. It’s a solution where everyone benefits.
Q: What message do you have for students who are about to major in chemistry?
A: Chemistry is the center of modern science. One of my research interests is catalyst science, which accounts for a significant percentage of China’s GDP. As mentioned above, the production of drugs involves a catalytic chemical reaction, which then produces new materials that have medical effects. Our clothes are also the result of the catalytic chemical reaction. The enzyme and energy acquisition in our body also needs a catalytic chemical reaction. In other words, catalytic chemical reaction and chemistry are everywhere in our lives. SUSTech has done a great job in integrating research and commercial application, so the future career prospects of SUSTechers are very promising. I welcome prospective students to apply for SUSTech and feel the university’s great vision – research, innovation, and entrepreneurship.
