Copper-catalyzed (4+1) and (3+2) cyclizations of iodonium ylides with alkynes
The copper(ii)-catalyzed (4+1) cyclizations and copper(i)-catalyzed (3+2) cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionaliz
Highly efficient heterogeneous synthesis of benzofurans under aqueous condition
Highly efficient organic reactions in water are important for designing environmental-friendly and low cost synthetic processes. Herein, we demonstrate an intermediate-in-water strategy for the heterogeneous synthesis of benzofurans in aqueous media. The cyclization reaction of 2-(phenylethynyl)phenol to 2-phenylbenzofuran cannot proceed in pure water. However, this reaction can be efficiently promoted by the formation of sparingly soluble intermediate in the presence of alkaline. Quantitative conversion of a variety of substrates to benzofuran derivatives has been achieved in the absence of noble metal catalyst. Other remarkable features including easy-isolation and purification of product, along with wide range of functional group tolerance render the methodology promising in the realm of green-synthesis.
Domino rhodium(I)-catalysed reactions for the efficient synthesis of substituted benzofurans and indoles
Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity for conjugate addition versus Heck-Mizoroki reaction can be achieved. In the case of 2-alkynyl pyridine electrophiles, novel 2-(benzofuran-3-yl)vinylpyridines are formed.
Boyer, Alistair,Isono, Naohiro,Lackner, Sebastian,Lautens, Mark
supporting information; experimental part
p. 6468 - 6482
(2010/10/03)
Rhodium(I)-catalyzed cyclization reaction of o-alkynyl phenols and anilines. Domino approach to 2,3-disubstituted benzofurans and indoles
A rhodium-catalyzed cyclization of o-alkynylphenols and anilines followed by intermolecular conjugate addition that succeeds with alkyl and aryl alkynes is reported. In this reaction, 2,3-disubstituted benzofurans or indoles are obtained in one pot in good to excellent yields.
Isono, Naohiro,Lautens, Mark
supporting information; experimental part
p. 1329 - 1331
(2009/10/02)
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