- Synthesis of benzofurans from the cyclodehydration of α-phenoxy ketones mediated by Eaton’s reagent
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Cyclodehydration of α-phenoxy ketones promoted by Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) is used to prepare 3-substituted or 2,3-disubstituted benzofurans with moderate to excellent yields under mild conditions. The method provides a facile access to benzofurans from readily available starting materials such as phenols and α-bromo ketones. The reaction is highly efficient, which is attributed to the good reactivity and fluidity of Eaton’s reagent. The reaction can be applied to prepare naphthofurans, furanocoumarins, benzothiophenes, and benzopyrans.
- Ma, Lin,Ma, Zhanwei,Zhang, Min,Zhou, Min
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p. 426 - 436
(2020/03/23)
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- The Selective Cross-Coupling of Secondary Alkyl Zinc Reagents to Five-Membered-Ring Heterocycles Using Pd-PEPPSI-IHeptCl
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The ability to cross-couple secondary alkyl centers is fraught with a number of problems, including difficult reductive elimination, which often leads to β-hydride elimination. Whereas catalysts have been reported that provide decent selectivity for the expected (non-rearranged) cross-coupled product with aryl or heteroaryl oxidative-addition partners, none have shown reliable selectivity with five-membered-ring heterocycles. In this report, a new, rationally designed catalyst, Pd-PEPPSI-IHeptCl, is demonstrated to be effective in selective cross-coupling reactions with secondary alkyl reagents across an impressive variety of furans, thiophenes, and benzo-fused derivatives (e.g., indoles, benzofurans), in most instances producing clean products with minimal, if any, migratory insertion for the first time. A wide variety of five-membered-ring heterocycles were successfully cross-coupled to secondary alkyl zinc reagents with the new precatalyst Pd-PEPPSI-IHeptCl, which features a bulky N-heterocyclic carbene ligand. This catalyst suppresses migratory-insertion (rearrangement) pathways, and the desired products are thus formed with high selectivity.
- Atwater, Bruce,Chandrasoma, Nalin,Mitchell, David,Rodriguez, Michael J.,Pompeo, Matthew,Froese, Robert D. J.,Organ, Michael G.
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supporting information
p. 9502 - 9506
(2015/08/11)
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- THERAPEUTIC AGENTS, AND METHODS OF MAKING AND USING THE SAME
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In part, the present invention is directed to antibacterial compounds
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Page/Page column 119
(2010/11/27)
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- Halocarbon Chemistry. 3. Ortho Metallation-Induced Cyclization of Acetylenes: One-Flask Synthesis of 2,3-Disubstituted Benzofurans, Thianaphthenes, and Indoles
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A new base-induced cyclization is described which involves the direct one-pot conversion of trifluoroethyl phenyl ethers, thioethers, and amines, in the presence of 4 equiv of alkyl- or aryllithium reagents, to 2,3-disubstituted benzofurans, thianaphthene
- Johnson, Francis,Subramanian, Raghupathi
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p. 5040 - 5041
(2007/10/02)
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