Cp*Ir(iii) and Cp*Rh(iii)-catalyzed annulation of salicylaldehydes with fluorinated vinyl tosylates

Abstract

A mild, selective and redox-neutral Cp*Ir(III)- and Cp*Rh(III)-catalyzed C-H activation/annulation of salicylaldedydes with fluorovinyl tosylates is reported. The use of mono-fluorovinyl tosylate favors C2- and C3-substitution-free chromones synthesis via C-H...

Rh(iii)-catalyzed redox-neutral C–H alkenylation of benzamides with gem-difluorohomoallylic silyl ethers via β-H elimination

“…Based on these experimental results and previous reports, 9–17,22 a plausible mechanism is illustrated in Scheme 7. Initially, the active Cp*Rh( iii ) is generated, followed by cyclometalation of N -methoxybenzamide 1 to afford a five-membered rhodacycle intermediate II , to which difluorohomoallylic silyl ether 2 coordinates and inserts to give seven-membered rhodacycle III .…”

“…Recently, transition metal-catalyzed direct C – H functionalization for accessing organofluorine compounds from fluorinated synthons has achieved notable breakthroughs, as elegantly developed by Yi, 9 Wang, 10 Loh and Feng, 11 Li, 12 Ackermann 13 and others. 14 Generally, gem -difluorine-containing alkynes and olefins are often used as valuable and readily accessible coupling partners.…”

Rh(III)-Catalyzed Oxidative C–H Activation/Annulation of Salicylaldehydes with Masked Enynes for the Synthesis of Chromones

“…Thereinto, salicylaldehydes, a type of versatile building blocks, have received significant attention . With the assistance of hydroxyl groups, sequential C–H activation/annulation could generate a series of oxygen-containing heterocycles, ,− including chromones. Chromones are prevalent structural motifs in numerous natural products and have been extensively explored due to their wide range of significant biological activities .…”

“…Chromones are prevalent structural motifs in numerous natural products and have been extensively explored due to their wide range of significant biological activities . With fluorovinyl tosylates, sulfoxonium ylides, diazo compounds, alkynes and gem -dichloroalkenes as coupling counters, various chromones could be achieved through transitional-metal-catalyzed sequential C–H activation/annulation of salicylaldehydes (Scheme ). In spite of these progress, further development of methods to construct novel skeletons, for example, 3-vinylchromones, still have its value in organic synthesis.…”

Cascade in Situ Iodination, Chromone Annulation, and Cyanation for Site-Selective Synthesis of 2-Cyanochromones

“…In this context, a series of new synthetic methods by means of chromone ring construction have been established. For the sake of constructing the chromone ring, a plethora of acyclic building blocks such as functionalized phenyl alkynones, salicylaldehydes, α-diazo halophenyl 1,3-diketones, O -functionalized 2-hydroxyphenyl acetones . etc., have been proved to be applicable for the synthesis of functionalized chromones.…”