Iridium-Catalyzed Regioselective B(3)-Alkenylation/B(3,6)-Dialkenylation of o-Carboranes by Direct B-H Activation

Ruofei Cheng; Zaozao Qiu; Zuowei Xie

doi:10.1002/chem.202000549

Iridium-Catalyzed Regioselective B(3)-Alkenylation/B(3,6)-Dialkenylation of o-Carboranes by Direct B-H Activation

Chemistry. 2020 Jun 5;26(32):7212-7218. doi: 10.1002/chem.202000549. Epub 2020 Mar 20.

Authors

Ruofei Cheng¹, Zaozao Qiu^{1

2

3}, Zuowei Xie^{1

4}

Affiliations

¹ Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, University of, Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Rd, Shanghai, 200032, P. R. China.
² CAS Key Laboratory of Energy Regulation Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of, Sciences, 345 Lingling Rd, Shanghai, 200032, P. R. China.
³ Fujian Innovation Academy, Chinese Academy of Sciences, 155 Yangqiao Rd West, Fuzhou, 350002, P. R. China.
⁴ Department of Chemistry, State Key Laboratory of, Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, P. R. China.

PMID: 32040221
DOI: 10.1002/chem.202000549

Abstract

Iridium-catalyzed formal alkyne hydroboration with cage B-H of o-carborane has been achieved, leading to the controlled synthesis of a series of 3,6-[trans-(AlkCH=CH)]₂ -o-carboranes (Alk=alkyl), 3-cis-(ArCH=CH)-o-carboranes (Ar=aryl), and 3-cis-(ArCH=CH)-6-trans-(AlkCH=CH)-o-carboranes in high yields with excellent regio- and very good cis-trans selectivity. The most electron-deficient B(3,6)-H vertices favor oxidative addition on electron-rich metal centers, which is responsible for the regioselectivity. On the other hand, the configuration of the resultant olefinic units is dominated by alkyne substituents. Alkyl groups lead to a trans-configuration whereas bulky aryl substitutions result in cis-configuration.

Keywords: B−H activation; alkenylation; carboranes; catalysis; transition metals.

Abstract

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