For detailed descriptions of previous and ongoing research projects please see our group pages at http://www.cjrgroup.com.
My research is primarily concerned with developing catalysts for the rapid, efficient and enantioselective synthesis of high value chiral organic compounds from low value achiral precursors. The products obtained are exploited for the synthesis of novel and potentially bioactive compounds, including alkaloid derivatives and iminosugars. The discovery of catalysts is underpinned by the development of simple methodologies for the generation of planar chiral metallocenes, and the enantioselective functionalisation of unactivated C-H bonds. In addition I am interested in complex chemical systems, catalytic networks and their possible relevance to prebiotic chemistry.
Current research projects include:
Nucleophilic catalysis
Novel chiral 4-amino pyridine based nucleophilic catalysts 1 and 2 have been synthesised in just a few steps from commercially available (S,S)-hexane-2,4-diol. The application and optimisation of these catalysts is currently under investigation. For example, 1 is an efficient catalyst for the Steglich rearrangement, providing access to scalemic compounds containing quaternary stereogenic centres.
Lead references: (a) H. V. Nguyen, M. Motevalli and C. J. Richards, Synlett, 2007, 725. (b) H. V. Nguyen, D. C. D. Butler and C. J. Richards, Org. Lett. 2006, 8, 769.
Palladacycles in asymmetric catalysis
Methods have been devised for the synthesis of chiral palladacycles exemplified by 3, 4 and 5. The application of these as Lewis acid type catalysts is being actively pursued. For example, 3 catalyses the Michael reaction of activated nitriles, and 4 is a highly enantioselective catalyst for the rearrangement of allylic imidates.
Lead references: (a) F. X. Roca and C. J. Richards, Chem. Commun., 2003, 3003. (b) F. X. Roca, M. Motevalli and C. J. Richards, J. Am. Chem. Soc. 2005, 127, 2388. (c) H. Nomura and C. J. Richards, Chem. Eur. J. 2007, 13, 10216.
The synthesis of alkaloids
The sequential application of metal catalysed reactions is being exploited for the rapid synthesis of alkaloid natural products and related potentially bioactive hydroxylated mono and bicyclic nitrogen heterocycles
Lead reference: (a) H. Nomura and C. J. Richards, in preparation.
The asymmetric synthesis of planar chiral metallocenes
Underpinning much of the group’s work in asymmetric catalysis is the development of methodologies for the synthesis of planar chiral metallocenes. Examples include the synthesis of palladacycles 4 (diastereoselective palladation) and 5 (enantioselective transcyclopalladation). Other methods include the use of (S)-3-butyn-2-ol as a common commercially available starting material for the synthesis of a variety of planar chiral metallocenes. The viability of this approach was recently demonstrated with the moderately diastereoselective synthesis of metallocenes 6 and 7.
Lead reference: C. J. Taylor, M. Motevalli and C. J. Richards, Organometallics, 2006, 25, 2899.
