Palladium-Catalyzed C-H Benzannulation of Functionalized Furans and Pyrroles with Alkynes

A benzannulation strategy involving activation of two C-H bonds of five-membered heteroarenes was developed. Readily available furans and pyrroles stabilized by synthetically useful electron-withdrawing groups underwent Pd-catalyzed 1:2 annulation reactions with diaryl alkynes. A variety of function...

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Published inSynthesis (Stuttgart) Vol. 53; no. 17; pp. 3001 - 3010
Main Authors Seo, Jia, Chen, Che-Wei, Lee, Woohyeong, Jeon, Ju Eun, Chen, Pei-Ling, Chuang, Shih-Ching, Joo, Jung Min
Format Journal Article
LanguageEnglish
Published STUTTGART Thieme Medical Publishers 01.09.2021
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
ACTIVATION
PYRAZOLES
alkynes
ARYLATION
ARENES
pyrroles
REGIOSELECTIVITY
HETEROAROMATIC-COMPOUNDS
indoles
benzannulation
furans
BONDS
palladium
oxygen
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Summary:A benzannulation strategy involving activation of two C-H bonds of five-membered heteroarenes was developed. Readily available furans and pyrroles stabilized by synthetically useful electron-withdrawing groups underwent Pd-catalyzed 1:2 annulation reactions with diaryl alkynes. A variety of functional groups, including ester, amide, ketone, aldehyde, and nitrile, on the heterocyclic cores were tolerated in the Pdcatalyzed oxidative reactions. In these reactions, the combination of 2,2-dimethylbutyric add and its conjugate base facilitated metalation at the heteroaromatic rings and reoxidation of the Pd(0) species using oxygen as the terminal oxidant. This strategy provides fluorescent benzofuran and indole derivatives and is expected to allow for further development of functionalized polycyclic heteroaromatic compounds.
ISSN:0039-7881
1437-210X
DOI:10.1055/a-1502-3641