在高区域选择性炔烃环三聚反应中，铬-铬五重键的可逆断裂/形成。
Reversible Cleavage/Formation of the Chromium-Chromium Quintuple Bond in the Highly Regioselective Alkyne Cyclotrimerization.
机构信息
Department of Chemistry and Frontier Research, Center on Fundamental and Applied Sciences and Matters, National Tsing Hua University, 101, Sec. 2, Guang-Fu Road, Hsinchu, 300, Taiwan.
Institute of Bioinformatics and Systems Biology and Department of Biological Science and Technology, National Chiao Tung University, 75 Bo-Ai Street, Hsinchu, 300, Taiwan.
出版信息
Angew Chem Int Ed Engl. 2017 Nov 27;56(48):15427-15431. doi: 10.1002/anie.201709583. Epub 2017 Nov 2.
Herein we report the employment of the quintuply bonded dichromium amidinates [Cr{κ -HC(N-2,6- Pr C H )(N-2,6-R C H )}] (R=iPr (1), Me (7)) as catalysts to mediate the [2+2+2] cyclotrimerization of terminal alkynes giving 1,3,5-trisubstituted benzenes. During the catalysis, the ultrashort Cr-Cr quintuple bond underwent reversible cleavage/formation, corroborated by the characterization of two inverted arene sandwich dichromium complexes (μ-η :η -1,3,5-(Me Si) C H )[Cr{κ -HC(N-2,6- Pr C H )(N-2,6-R C H )}] (R= Pr (5), Me (8)). In the presence of σ donors, such as THF and 2,4,6-Me C H CN, the bridging arene 1,3,5-(Me Si) C H in 5 and 8 was extruded and 1 and 7 were regenerated. Theoretical calculations were employed to disclose the reaction pathways of these highly regioselective [2+2+2] cylcotrimerization reactions of terminal alkynes.
在此，我们报告了五键合二铬酰胺基[Cr{κ -HC(N-2,6- Pr C H )(N-2,6-R C H )}]（R=iPr（1），Me（7））作为催化剂，介导末端炔烃的[2+2+2]环三聚反应，生成 1,3,5-三取代苯。在催化过程中，超短的 Cr-Cr 五重键发生可逆的断裂/形成，这得到了两个反转的芳基夹心二铬配合物（μ-η：η -1,3,5-（Me Si）C H）[Cr{κ -HC（N-2,6- Pr C H ）（N-2,6-R C H ）}]（R= Pr（5），Me（8））的表征的证实。在σ给体（如 THF 和 2,4,6-Me C H CN）的存在下，桥连芳基 1,3,5-（Me Si）C H 在 5 和 8 中被挤出，生成 1 和 7。理论计算被用来揭示这些末端炔烃高区域选择性[2+2+2]环三聚反应的反应途径。
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