Catalytic Electron Transfer Reactions for Preparation of Aza-Heterocycles

Catalytic Electron Transfer Reactions for Preparation of Aza-Heterocycles

Koichi NARASAKA

Abstract:

Although we are unconsciously using one-electron oxidation and reduction processes to activate organic molecules, electron transfer processes are not well recognized as efficient synthetic tools. This is mainly due to stoichiometric use of oxidation and reduction reagents. In our group, development of synthetic methods (C-C and C-N bond formations) are being studied by designing catalytic electron transfer systems. In this lecture, some of these examples are introduced, particularly for the synthesis of aza-heterocycles.

DEVELOPMENT OF NEW SYNTHETIC METHODS IN ORGANIC SYNTHESIS: SYNTHETIC STUDIES TOWARDS THE TOTAL SYNTHESIS OF GRAYANOTOXINS

Hao Li, Kiew-Ching Lee and Teck Peng Loh

Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore

The growth of organic synthesis depends on the discovery of novel and practical methods and reagents. In our group, we have been interested to discover new synthetic methods and concepts from the total synthesis of complex natural products. In this presentation, I will discuss on our efforts directed towards the total synthesis of grayanotoxin. The discovery of new cascade reactions to construct the five membered ring (A)1 as well as Diels-Alder reaction involving highly substituted dienophiles2 will also be discussed.

Biological Activities: Action on sodium channels by increasing the permeability of sodium ions in excitable membranes

Structural Features: Polyhydroxylated Tetracyclic carbon framework; 5, 6, and 7-membered rings, 10 stereogenic centers with 4 quartenary centers

Total Synthesis: Shirahama3 research group (37 steps) in 1994

Our strategy: cascade reactions to construct the 5-membered ring and Diels-Alder involving highly substituted dienophile

References:

1. H. Li and T-P Loh, J. Am. Chem. Soc. 130, 7194-7195 (2008)

2. Dr Kiew-Ching Lee, PhD Thesis (NUS), 2005

3. Kan, T.; Hosokawa, S.; Nara, S.; Oikawa, M.; Ito, S.; Matsuda, F.; Shirahama, H J. Org. Chem, 1994, 5532-5534

Teck Peng Loh, Professor and Associate Chair (Research), School of Physical and Mathematical Sciences, joined Nanyang Technological University since February 2005. During his 11 years, from 1994 to 2005, at National University of Singapore, he had risen from the ranks of a Lecturer, Senior Lecturer, and Associate Professor to a Professor in 2004. He had won several University Outstanding Researcher Award and Faculty Teaching Excellence Award in NUS, Nanyang Award 2007 - Research and Innovation in NTU and was also the Program leader of the Medicinal Chemistry program in NUS. Besides being engaged in teaching, research and participation in international conferences, his professional appointments include the Advisory Board Member of ISCFC-07 held in NTU 2007, Advisory Board Member of Chemistry Communications coordinator of “Asia Core Program”, Honorary Secretary of Singapore National Institute of Chemistry and Chairman of the Singapore International Chemistry Conference (SICC-4).

CURRICULUM VITAE

NAME: Koichi Narasaka

DATE AND PLACE OF BIRTH: May 6, 1944; Miyagi, Japan; Japanese

EDUCATIONAL EXPERIENCE:

B. Sc. Tokyo Institute of Technology, 1967

M. Sc. Tokyo Institute of Technology, 1969

Ph. D. Tokyo Institute of Technology, 1972 (Professor T. Mukaiyama)

PROFESSIONAL EXPERIENCE:

Research Associate Departmant of Chemistry, Tokyo Institute of Technology, 1972-1973

Research Associate Department of Chemistry, Faculty of Science, The University of Tokyo, 1973-1975

Lecturer Department of Chemistry, Faculty of Science, The University of Tokyo, 1975-1978

Postdoctoral Fellow Harvard University (Professor E. J. Corey), 1975-1976

Associate Professor Department of Chemistry, Faculty of Science, The University of Tokyo, 1978-1987

Professor Department of Chemistry, Faculty of Science, The University of Tokyo, 1987-2007

Nanyang Professor Division of Chemistry and Biological Chemistry, Nanyang Technological University, 2007- present

EDITORIAL WORKS

Organic Syntheses (Editor);

Phy. Org. Chem. (Editor)

Bull. Chem. Soc. Jpn. (Senior Editor, Advisory Board);

Chem. Lett. (Editor-in-Chief);

Organic Lett. (Advisory Board)

Tetrahedron and Tetrahedron Letters (Advisory Board)

HONORS:

The Chemical Society of Japan Award for Young Chemist, 1979

Fellow of the Kurata Foundation, 1980

Fellow of the Takeda Foundation, 1982

Fellow of the Tokuyama Science Foundation, 1989

Fellow of Ciba-Geigy Science Foundation, 1993

The Chemical Society of Japan Award, 2000

Louis Pasteur Medal (France), 2001

Merck Schuchardt-Lectureship (Germany), 2002

IAP Lectureship (Columbia University, USA), 2002

Boehringer Ingelheim Lecture Award (University of Toronto, Canada), 2003

Visiting Lecturer of the Chemistry Research Promotion Center (Taiwan), 2003

Toray Science and Technology Prize, 2005

Emeritus Professor, The University of Tokyo, 2007

The Fellow of the Chemical Society of Japan, 2008

Research Interest

Development of Synthetic Organic Reactions and Total Synthesis of Natural Products

1) Acyclic stereocontrol and catalytic asymmetric reactions.

2) Lewis acids and transition metal catalysts in organic synthesis (B, Ti, Pd, Rh, Re, Mn, Cu)

3) One electron oxidation and reduction for activation of organic molecules (Radical Chemistry)

4) C-N Bond formation with oxime derivatives

5) Organic reaction mechanisms

6) Total synthesis of terpenes, alkaloids, carbohydrates, etc.