CHIBA Shunsuke
picture_chiba

Professor
Head of Division

Education: B.Eng., Waseda University; M.Sc., Ph.D., The University of Tokyo

Research Area: Synthetic Organic Chemistry

Phone: (65) 6513 8013

E-mail: shunsuke@ntu.edu.sg

Webpage:http://www1.spms.ntu.edu.sg/~shunsuke/Chiba_Group/top.html



Research Interest

Development of New C-N Bond Forming Reactions
Nitrogen containing organic molecules have attracted much attention as bioactive compounds and functional materials. In our group are currently focused on the chemical reactivity of some nitrogen-containing small molecules such as organic azides and oxime derivatives, and their chemical activation for generation of nitrogen reactive species like metal-nitrene complexes, iminyl metal species, and iminyl radicals. Such chemical species would lead to the development of unprecedented C-N bond forming reactions. The products synthesized by these reactions are especially important in medicinal, agricultural, and natural product chemistry as well as in the material science.

For example, a Mn(III)-mediated divergent synthesis of substituted pyridines and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives was exploited using readily available vinyl azides and cyclopropanols with a wide range of substituents. The reactions of vinyl azides with monocyclic cyclopropanol provided pyridines in the presence of Mn(acac)3, whereas those with bicyclic cyclopropanols led to the formation of 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives using a catalytic amount of Mn(acac)3. These reactions may be initiated by a radical addition of b-keto radicals, generated by the one-electron oxidation of cyclopropanols, to vinyl azides to give iminyl radicals, which would cyclize with the intramolecular carbonyl groups.

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Recently, a Pd(II)-catalyzed ring expansion-reaction of cyclic 2-azidoalcohol derivatives was found to proceed via unprecedented C-C bond cleavage–C-N bond formation sequence, providing substituted azaheterocycles.

Synthesis of Natural and Unnatural Products
We are interested in synthesis of natural and unnatural products bearing complex chemical structures as well as attractive biological activities and chemical properties. Some of current target molecules in our group are described below.




Selected Publications

  1. A Pd(II)-Catalyzed Ring-Expansion Reaction of Cyclic 2-Azidoalcohol Derivatives: Synthesis of Azaheterocycles Chiba, S.; Xu, Y.-J.; Wang, Y.-F. Journal of the American Chemical Society, 2009, 131, 12886-12887. 

  2. Mn(III)-Mediated Reactions of Cyclopropanols with Vinyl Azides: Synthesis of Pyridine and 2-Azabicyclo[3.3.1]non-2-en-1-ol Derivatives Wang, Y.-F.; Chiba, S. Journal of the American Chemical Society, 2009, 131, 12570-12572.

  3. “Orthogonal Synthesis of Isoindole and Isoquinoline Derivatives from Organic Azides” Hui, B. W.-Q.; Chiba, S. Organic Letters, 2009, 11, 729-732.

  4. Mn(III)-Catalyzed Synthesis of Pyrroles from Vinyl Azides and 1,3-Dicarbonyl Compounds" Wang, Y.-F.; Toh, K. K.; Chiba, S.; Narasaka, K. Organic Letters, 2008, 10, 5019-5022.  (Highlighted in Synform 2009/06)