Acceleration of metallacycle-mediated alkyne-alkyne cross-coupling with TMSCl

作者：Cassidy James S; Mizoguchi Haruki; Micalizio Glenn C^*

来源：Tetrahedron Letters, 2016, 57(34): 3848-3850.

DOI：10.1016/j.tetlet.2016.07.045

• Titanium isopropoxide
• Directed reactions
• Metallacycle-mediated cross-coupling
• 1,3-Dienes

Investigation of titanium-centered metallacycle-mediated cross-coupling between unsymmetrical internal alkynes has led to the discovery that TMSCl significantly accelerates the C-C bond forming event. We report a collection of results that compare the efficiency of this reaction employing Ti(Oi-Pr)(4)/2n-BuLi in PhMe with and without TMSCl, demonstrating in every case that the presence of TMSCl has a profound impact on efficiency. While relevant in the context of developing this fundamental bond-forming process as an entry to more complex organometallic transformations, these modified reaction conditions allow coupling processes to be run at >10 times the concentrations previously possible [in 2.4 M n-BuLi (hexanes)], without the requirement of additional solvent. Finally, we demonstrate the effectiveness of these modified reaction conditions for the annulative cross-coupling between TMS-alkynes and 1,6-enynes leading to the formation of angularly substituted hydrindanes with, now well appreciated, high levels of regio- and stereoselection.

• 出版日期2016-8-24