Prof. Zhiping Li
Department of Chemistry
Renmin University of China
Beijing 100872, China
B.Sc.: Nanjing University of Science and Technology, 1989-1993
Ph.D.: Dalian University of Technology, 1996-1999 (with Professors Xigao Jian and Guodu Ren)
Postdoctoral Fellow: Peking University, 1999-2000 (with Professor Zhenfeng Xi)
Postdoctoral Fellow: Hokkaido University, Japan, 2001-2002 (with Professor Tamotsu Takahashi)
Postdoctoral Fellow: McGill University, Canada, 2004-2006 (with Professor Chao-Jun Li)
Assistant Professor: Peking University, 2002.8-2003.12
Associate Professor: Renmin University of China, 2006.3-2009.8
Professor: Renmin University of China, 2009.9-now
Qualifications and awards
Dr. Zhiping’s group is current focusing on seeking novel synthetic methodologies based on the selective oxidation of C-H bonds (Scheme 1).
(1) Iron-catalyzed C-H bond oxidation directed towards organic synthesis
The applications of inexpensive, easily available and nontoxic iron catalysts are attracting great attention in organic chemistry. Iron catalysts are well-known catalysts in C-H bonds oxidation, wherein C-O bonds and C-X bonds were formed. Inspired by nature and previous excellent results, we rationalized that it would be an efficient method of C-C bond formation by direct and selective C-H bond oxidation. Here are some of our recent results toward this idea, including benzylic C-H bond oxidation, α-heteroatom C-H bond oxidation and aromatic C-H bond oxidation (Scheme 2). Iron catalysts together with organic peroxide have been proved to be very efficient inoxidative C-H bond activation and C-C bond formation.
(2) Molecular iodine-mediated C-H bond oxidation in organic synthesis
Metal-free syntheses are highly attractive in synthetic chemistry, especially in pharmaceutical synthesis. The low cast and less toxicity molecular iodine is one of environmentally benign reagents and was broadly used in organic synthesis. Our efforts in the development of novel methodologies for organic synthesis promoted us to investigate molecular iodine-mediated C-H bond oxidation and C-C bond formation. Indole derivatives are the biologically important natural products. Many efforts have been made to achieve the synthesis of this motif. Various innovative and powerful methodologies for the synthesis of indole derivatives have been developed. With our efforts, an efficient and practical synthesis of indole and its derivatives was achieved via I2-mediated oxidative coupling reactions without sacrificed organic functional groups (Scheme 3).
(3) The application of o-chloranil in C-C bond formation
C-C bond formation is an important research topic in organic synthesis. Various methodologies are developed toward this target. As one of the fundamental innovations in organic chemistry, “chemistry beyond functional group transformation”, which uses readily available, cheap and non-toxic materials to construct targeted molecules with high yields under mild conditions, is highly desired.
o-Chloranil (tetrachloro-o-benzoquinone) is usually used as an oxidant in oxidation reactions. During our studies, o-chloranil was applied efficiently in C-C bond formation. Two types of C-C bond formation using o-chloranil will be discussed: (1) a novel Pummerer-type reaction is developed via o-chloranil-mediated C-H bond oxidation. The reaction presents a simple and efficient method to construct sulfide derivatives. Interestingly, the Knoevenagel-type reaction is selectively achieved by controlled reaction conditions (Eq.1); (2) efficient iron-catalyzed cross-aldol reactions of o-chloranil and methyl ketones are developed. Importantly, the formed aldol products are efficiently transformed into cyclohepta-2,4,6-trienone derivatives (tropones) under thermal condition via ring-expansion reactions (Eq.2). Further ring-contraction reactions of tropone derivatives is also interesting (Eq.3).