2013 Fiscal Year Annual Research Report
銅触媒による二酸化炭素を用いるアルケン及びアルキンのボリル化／カルボキシル化
| Project/Area Number |
24750047
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
張 亮 独立行政法人理化学研究所, 侯有機金属化学研究室, 研究員 (20610992)
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| Keywords | 二酸化炭素 / カルベン配位子 / 銅触媒 / カルボキシル化反応 / アルケン |
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| Research Abstract |
In FY2013, we focused on the investigation of the boracarboxylation of alkenes with carbon dioxide. We systematically screened N-heterocyclic carbene-copper complexes, solvents, temperature, and other reaction factors for a model reaction. The reaction of styrene with bis(pinacolato)diboron and carbon dioxide under mild conditions affords a beta-boralactone product in satisfying isolated yield. The structure of the product was confirmed by X-ray crystallographic analysis. The substrate scope of this transformation was then investigated in detail. It was found that the reactions of different substituted styrenes afford the corresponding desired products in good to excellent yields. The beta-substituted styrenes are also suitable substrates for this reaction, affording syn-addition products selectively. The acidification of the obtained beta-boralactone product proceeds smoothly to give the corresponding beta-boryl carboxylic acid in high yield. The one-pot boracarboxylation/acidification transformation of various styrenes were then investigated, affording the desired beta-boryl carboxylic acids efficiently. This kind of carboxylic group-containing alkylboranes may serve as useful building block in organic synthesis.
We also carried out stepwise stoichiometric reactions of related copper complexes. Several important reaction intermediates were successfully isolated and characterized. Based on the experimental results and rational analysis, a possible mechanism of the current reaction was proposed. A manuscript for publication of this work is now in preparation.
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