24382-05-6Relevant articles and documents
Inverse-electron-demand Diels-Alder reactions of 4-aryl-2-pyrones with electron-rich dienophiles
Balazs,Kadas,Toke
, p. 7583 - 7587 (2000)
The Diels-Alder reaction of 4-aryl-pyrones with electron-rich dienophiles afforded substituted biaryl derivatives in most cases. At the minimal temperatures necessary for a measurable conversion of the starting pyrones, the bicyclic lactones, the primary products of the condensation, underwent cycloreversion by extruding carbon dioxide and then aromatised through further eliminations. In the case of the more active 4-aryl-6-chloro-pyrone, a formal substitution was observed instead of the expected cycloaddition with an active dienophile, while in its reaction with a Schiff-base the primary product of the cycloaddition was trapped through the formation of a new tetrahydropyridine derivative. (C) 2000 Elsevier Science Ltd.
Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
, p. 208 - 218 (2021/12/29)
A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
Cobalt-Catalyzed Coupling of Aryl Chlorides with Aryl Boron Esters Activated by Alkoxides
Tailor, Sanita B.,Manzotti, Mattia,Smith, Gavin J.,Davis, Sean A.,Bedford, Robin B.
, p. 3856 - 3866 (2021/04/07)
The cobalt-catalyzed Suzuki biaryl cross-coupling of aryl chloride substrates with aryl boron reagents, activated with more commonly used bases, remained a significant unmet challenge in the race to replace platinum group metal catalysts with Earth-abundant metal alternatives. We now show that this highly desirable process can be realized using alkoxide bases, provided the right counterion is employed, strict stoichiometric control of the base is maintained with respect to the aryl boron reagent, and the correct boron ester is selected. Potassium tert-butoxide works well, but any excess of the base first inhibits and then poisons the catalyst. Lithium tert-butoxide performs very poorly, while even catalytic amounts of lithium additives also poison the catalyst. Meanwhile, a neopentane diol-based boron ester is required for best performance. As well as delivering this sought-after transformation, we have undertaken detailed mechanistic and computational investigations to probe the possible mechanism of the reaction and help explain the unexpected experimental observations.
