Research projects

有機合成反応に対するマイクロ波作用は，熱的効果に加えマイクロ波特異効果の存在が議論されてきた。申請者は触媒的不斉合成反応へのマイクロ波適用により，それらの分離に成功した。本研究ではマイクロ波特異効果の適用一般化を目指し，マイクロ波照射で加速される反応系の開拓と，定量的取り扱い，反応速度論解析により，有機合成化学におけるマイクロ波適用の指針を示し，有機合成反応開発の革新発展に寄与することを目指す。

The microwave specific effect was verified in the Nazarov cyclization reaction. Based on the quantification of the reaction acceleration by kinetic analysis, the maximum acceleration of 5.8 times was confirmed. Reaction acceleration was also observed in the thermal Nazarov cyclization reaction without any loss of chiral transfer rate. In the development research of absolute asymmetric synthesis using circularly polarized microwaves, a joint research was made on the setting of reaction system by physical measurement of circularly polarized microwaves. Furthermore, we have developed a joint research on the hypothesis that the microwave specificity effect is based on entropy effect, and found a possibility to elucidate the mechanism by terahertz spectroscopy.

The effect of circularly polarized microwave irradiation was examined. Substrate was charged, without irradiation, or under right-handed / left-handed CPM irradiation, and the ee of the reduced product was analyzed. When the asymmetric catalysis was irradiated with 12.4 GHz CPM, the ee under the right-handed conditions was improved more than the non-irradiated conditions, but decreased in the left-handed conditions. In the 2.45 GHz / 50 W CPM irradiation to the racemic catalytic reaction, both the right-handed and the left-handed conditions improved, and the microwave effect should be considered. The CPM effect on atropo-isomerization reaction was examined. After 2.45 GHz / 20 W CPM irradiation, the ee was analyzed after reduction to prevent from racemization. As a result of the statistical processing, we found reaction conditions that the enantiomeric excess was observed in the opposite directions on the left-handed and the right-handed, though in the racemic 95% confidence interval.