| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
In this research, we first investigated the nature ot the interaction of the ion radical pairs generated by photoreaction of carbonyl compounds and amines. We then paid our attention to the reductive transformation ot several substrates and the synthesis of new electron donor compounds. Through these efforts, several interesting observations were obtained as described below. For example, photoreaction of bromomethyl substituted benzocyclic ketones and various amines revealed that the selectivity of the reaction course for the radical intermediates derived from these compounds was significantly influenced by the nature of the amine cation radicals involved. Particularly, photoreaction of these carbonyl compounds with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) was noteworthy. The Intermediate carbon radicals derived from these substrates could abstract hydrogen atom from DMPBI cation radical to afford observed products. On the other hand, same carbon radicals could be reduced by DMPBI
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radical generated from the deprotonation of DMPBI cation radical by added bases to become the carbanions giving same products through protonation. In the connection with our purpose of the development of highly efficient and selective phtotransformation using DMPBI and its derivatives, we conducted photo-reduction of epoxy ketones with the combination of DMPBI and acetic acid to produce desired hydroxy ketones in good yields. In this reaction, isolation of the oxidized DMPBI, 1,3-dimethyl-2-phenylbenzimidazolium salt was first succeeded. 2-Naphthyl and 2-anthryl substituted 1,3-dimethylbenziimidazolines were synthesized and were found to be effective for the photoinduced reduction of some carbonyl compounds. In order to find new substrates which could be applicable to the above phtochemical systems, samarium diiodide reduction of several carbonyl compounds were also conducted. Then, unprecedented intramolecular nucleophilic reactivity of ketyl radicals was discovered. We hope that our continuous investigation in this and the related areas will allow us to develop new photoinduced electron transfer reaction systems using DMPBI and its analogues. Less
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