Lewis acid-mediated β-selective hydrocarboxylation of α, α-diaryl- and α-arylalkenes with R3SiH and CO2. Issue 24 (10th June 2015)

• Record Type: Journal Article
• Authors: Tanaka, Shinya; Tanaka, Yuuki; Chiba, Masafumi; Hattori, Tetsutaro
• Is Part Of: Tetrahedron letters. Volume 56:Issue 24(2015)
• Page Start: 3830
• Page End: 3834
• Publication Date: 2015-06-10
• Subjects: Carbon dioxide -- Lewis acid -- Hydrocarboxylation -- Alkene -- Chlorosilane; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2015.04.090
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Abstract: α, α-Diarylalkenes are successfully hydrocarboxylated with Et3 SiH and CO2 with the aid of Et3 SiB(C6 F5 )4 or EtAlCl2 /Ph3 SiCl to give carboxylic acids with a carboxy group at the β-position to the aryl groups. The EtAlCl2 /Ph3 SiCl-mediated reaction is also applicable to various α-arylalkenes. 1 H NMR analysis of a mixture of EtAlCl2, Ph3 SiCl, and Et3 SiH strongly suggests the formation of a μ -H complex, [Ph3 Si–H–SiEt3 ] + AlEtCl3 −, which is an equivalent of R3 Si + ions, while Et3 SiB(C6 F5 )4 is an ion pair with a Et3 Si + ion. Therefore, in these reaction systems, a siloxycarbonylium, R3 SiOCO +, is considered to be a common electrophile, the addition of which to the substrate, followed by trapping of the resulting cationic species with Et3 SiH seems to afford the desired acid after aqueous workup.