Eietsu
HASEGAWA (EH) Group at Niigata
University, Japan
About EH
and his research
Educational
background and Academic career
Education
B. Sci. 1980 Yamagata University,
supervised by Professor Kaoru Hanaya
Dr. Sci. 1985 Tohoku University,
supervised by Professor Toshio Mukai
Employment
Postdoctoral
Fellow 1986 (February)–1987 (September) University of Maryland with
Professor
Patrick S. Mariano (currently, University of New
Mexico, Professor Emeritus)
Assistant
Professor 1987 (October)–1992 (March) Niigata University
Associate
Professor 1992 (April)–2006 (May) Niigata University
Professor 2006 (June)–2023 (March) Niigata
University
Professor
Emeritus 2023– Niigata University
Visiting
Scholar
Visiting
Research Associate Professor 1992
(March)–1993 (January) University of Pittsburgh
with Professor Dennis P. Curran
(currently, Distinguished Service Professor of
Chemistry)
Visiting
Research Associate 1999 (March) Steacie Institute
for Molecular Sciences, National Research Council Canada (NRCC) with Dr. Danial
D. M. Wayner (previously, Departmental Science
Advisor and Chief Science Officer of NRCC)
Award
The Japanese Photochemistry
Association Award for Distinguished Contribution to Photochemistry 2022
Research
interests
Keywords
Organic
chemistry, particularly focused on electron transfer reactions, photochemistry,
radical intermediates, and green-sustainable chemistry
Research
topics
1) Photoinduced electron
transfer (PET) reaction of organic compounds
PET promoted reductive transformations of organic
compounds utilizing amines as electron donors have been long-time research
topics in our group. Then, we discovered that N-heterocyclic aromatic amines such as 1,3-dimethyl-2-phenyl benzimidazoline and its derivatives act as exceptionally
effective electron and hydrogen atom donors in various PET reaction systems.
For example, 2-hydroxyaryl-1,3-dimethylbenzimidazolines, acting as formal two
hydrogen atom-donors, were successfully applied to reductive transformations of
carbonyl compounds including epoxy ketones, aryl halides and sulfonyl compounds.
In the oxidative transformation event, PET promoted regioselective ring-opening
reaction of bicyclic cyclopropyl silyl ethers was developed. Recently, benzimidazolium
aryloxides (inner salts = betaines) were developed as unprecedented betaine
photocatalysts. Moreover, new photocatalytic protocols based on the systems
consisting of polycyclic aryl or triarylamine substituted benzimidazoliums and
co-operating materials have been successfully developed.
2) Thermal transformation
of organic compounds promoted by redox reagents
Samarium diiodide (SmI2)
promoted reductions of carbonyl substrates and organic halides are studied. In
these reactions, intramolecular reactivity of samarium ketyl
radicals with other functional groups, such as carbon-halogen bonds and ester
carbonyls, is particular interest. One of most notable reactions is novel
cyclization and ring-expansion reaction initiated by intramolecular samarium ketyl-ester coupling. Also, oxidative ET reaction of
certain cyclopropanol derivatives promoted by Fe (III), Ce (IV), Mn (III) and
Cu (II) salts and amine radical cation salts is investigated. A recent
discovery of solvent dependent contrastive reaction pathways promoted by Cu
(II) salts is particularly noteworthy.
3) Green and sustainable (GS)
electron transfer (ET) chemistry and radical chemistry
Development of
environmentally benign ET methods to achieve organic transformations is our
interest. For this objective, improvement of the efficiency as well as the
selectivity of above described reactions is required.
Also, discovery of effective ET reactions using
environmentally benign solvents such as ionic liquids, fluorine containing
organic solvents is interesting. In addition, development of free
radical reactions without organotin hydrides and benzene is investigated. For
example, benzotrifluoride was found to be an
effective solvent both for free radical reactions using an organosilicon
hydride and for some electron-transfer reactions. In addition, shortening of
reaction operation processes is also compatible with GS concept. Thus,
development of one-pot reaction protocols is also our interest.
(Last updated: 8/2023)