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.
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。
