Fuctionalising carboranes 

20 August 2015

The Croucher Foundation has approved a three-year grant totalling one million Hong Kong dollars to the Shanghai Hong Kong Joint Laboratory in Chemical Synthesis, for its research on carborane functionalisation. The research, supported under the Chinese Academy of Sciences Croucher Funding Scheme for Joint Laboratories, aims to develop new synthetic methods by using five-member metallacycles.

Carborane functionalisation is of much interest in the chemistry world, as carboranes are potentially highly useful units in boron neutron capture therapy, supramolecular design, and coordination chemistry. Many chemists have been developing new synthetic methods, so as to help increase carboranes’ application in the fields of medical, material science, and coordination chemistry.

Carboranes are clusters of boron, carbon and hydrogen atoms. They are structurally unique molecules- thermally and chemically stable, with the ability to hold various substituents. These stabilities make them ideal as basic blocks for polymer, ceramics and boron based cancer therapy, but their stabilities also make them extremely difficult to synthesize into large carboranes. So far, only a few derivatisation techniques are known.

Researchers at the Joint Lab expect to investigate systematically the reaction chemistry of five-member metallacycles and examine the role of transition metals in these reactions. They plan to prepare a series of new functional carboranes and explore their applications in organic materials.

A powerful strategy to assemble complex molecules from very simple precursors in a single operation, multi-component reactions (MCRs) are a convergent reaction where three or more compounds react to form a single product, which retains majority of the atoms of the starting materials. To achieve molecular selectivity during the process, transition metals are often used since complexation of a metal centre to an unsaturated molecule significantly modifies the reactivity of the moiety. Researchers at the Joint Lab plan to develop transition metal-mediated MCRs of carborynes (1,2-dehydro-o-carborane / 1,3-dehydro-o-carborane) with unsaturated molecules. They will use different metals in a one-pot operation to control the reactivity of different molecules via the cooperative action of metals.

The research team at the Joint Lab is led by Professor Xie Zuowei from The Chinese University of Hong Kong and Professor You Shuli from the Shanghai Institute of Organic Chemistry. Recently, the team has achieved three-component [2+2+1] cross-cyclotrimerization of carboryne, alkene, and alkyne for dihydrofulvenocarborane preparation (J. Am. Chem. Soc. 2013, 135, 18742−18745) and has reported the synthesis, characterization and reactivity of a mixed-sandwich zirconacarborane alkyl (Inorg. Chem. Front., 2015, 2, 467–472). According to Professor Xie, the researchers will develop new methods to prepare carborane derivatives and enhance their understanding of the reaction chemistry of metallacarborynes.

Shanghai Hong Kong Joint Laboratory in Chemical Synthesis

The Shanghai Hong Kong Joint Laboratory in Chemical Synthesis (Joint Lab) was established in 1999 as a tripartite arrangement between the Shanghai Institute of Organic Chemistry (SIOC), The Chinese University of Hong Kong (CUHK) and The University of Hong Kong (HKU).

The Joint Lab has opened up opportunities to harness synergies and to interlink knowledge for the three participating parties in achieving excellence in chemical syntheses involving organic, inorganic and organometallic chemistry.

Currently, the goal of the Joint Lab is to conduct basic research in the development of new methods for the preparation of valuable molecules, such as bio-active agents and advanced functional molecules.

Professor Xie Zuowei

Professor XIE Zuowei is a Choh-Ming Li Professor of Chemistry in the Department of Chemistry at The Chinese University of Hong Kong. Professor Xie is an internationally recognised chemist with expertise in organometallic chemistry and is distinguished for his work in the areas of carboranes, supercarboranes and metallacarboranes. Professor Xie has received several prestigious awards including the State Natural Science Awards in 2008 and 1997, the Chinese Chemical Society Yao-Zeng Huang Award in Organometallic Chemistry in 2010, and the Croucher Senior Research Fellowship in 2003.

Professor You Shuli

Professor You Shuli has been serving as a Full Professor at SIOC since 2006. His current research interest includes asymmetric C-H functionalisation and asymmetric dearomatisation reactions. Professor You has published over 160 peer-reviewed papers and 7 book chapters, and applied over 30 Chinese patents as a co-inventor. He has received numerous awards from renowned organizations and most recently the Royal Society of Chemistry Merck Award 2015.

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