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Synfacts 2012; 8(2): 0219
DOI: 10.1055/s-0031-1290043
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart · New York

ortho-C–H Borylation of Arenes Using Silica-Supported Rhodium Complexes

Contributor(s):
Yasuhiro Uozumi
,
Yoichi M. A. Yamada
,
Takuma Sato
Kawamorita S, Miyazaki T, Ohmiya H, Iwai T, Sawamura M * Hokkaido University, Sapporo, Japan
Rh-Catalyzed Ortho-Selective C–H Borylation of N-Functionalized Arenes with Silica-Supported Bridgehead Monophosphine Ligands.

J. Am. Chem. Soc. 2011;
133: 19310-19313
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Publication History

Publication Date:
19 January 2012 (online)

 
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Key words

rhodium - C–H activation - borylation - SMAP - silica-supported catalysis

Significance

ortho-C–H Borylation of N-functionalized arenes with solid-supported Rh catalysts was described. A Rh complex prepared in situ from [Rh(OH)(cod)]2 and silica-SMAP (a silica-supported 1-phospha-4-silabicyclo[2.2.2]octane derivative) was found to promote the ortho-borylation efficiently. In the presence of 0.5 mol% Rh (Rh/P = 1:1), the reaction of 2-phenylpyridine (1) with bis(pinacolato)diborone (2) gave 2-(2-pyridyl)phenylboronic acid pinacol ester (3) in 98% yield based on 2.


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Comment

In the presence of Ph-SMAP (4-phenyl-1-phospha-4-silabicyclo[2.2.2]octane) instead of silica-SMAP, product 3 was obtained in only 17% GC yield. The catalyst was readily separated from the reaction mixture by filtration using Celite, although attempts to reuse the catalyst were unsuccessful.


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