Recyclable Pd/C catalyzed one-step reduction of carbonyls to hydrocarbons under simple conditions without extra base

A rhodium-catalyzed C-H activation/cyclization approach toward the total syntheses of cassiarin C and 8-O-methylcassiarin A from a common intermediate

Three short and efficient total syntheses of cassiarin C are reported, from a chromanone common key intermediate. A C-H activation strategy, under rhodium catalysis on its pivaloyl oxime, enabled the installation of the pyridine ring. Dehydrogenation of 8-O-methylcassiarin C afforded 8-O-methylcassiarin A. A kinetic experiment and DFT calculations of the intermediates helped to gain insight into the unusual site- and stereo-specific H/D exchange of cassiarin C in CD3OD.

Palladium-Catalyzed Trifluoroacetylation of Arylboronic Acids Using a Trifluoroacetylation Reagent

A new trifluoroacetylation reagent was developed by using inexpensive and readily available trifluoroacetic anhydride and N-phenyl-4-methylbenzenesulfonamide for the first time. The reaction of (het)aryl boronic acids with the new trifluoroacetylation reagent, N-phenyl-N-tosyltrifluoroacetamide, proceeded smoothly in the presence of a palladium catalyst to provide trifluoromethyl ketones in satisfactory to excellent yields. Various groups, including the synthetically useful functional groups Cl, TMS, and PhCO, were tolerated well under the current reaction conditions. This new trifluoroacetylation reagent can be used in the large-scale synthesis of trifluoromethyl ketones, even at a low palladium catalyst loading.

Ru(dppbsa)-catalyzed hydrodeoxygenation and reductive etherification of ketones and aldehydes

Ru(dppbsa)-catalyzed hydrodeoxygenation and reductive etherification of ketones and aldehydes were developed. The carbonyl substrates without β-CH functionality follow the hydrogenation-hydrogenolysis path, wherein the hydrogenolysis of the alkanol intermediates presents as...

A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2 and tBuOK

A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh₂ and ^tBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.

Bromine radical as a visible-light-mediated polarity-reversal catalyst

Polarity-reversal catalysts enable otherwise sluggish or completely ineffective reactions which are characterized by unfavorable polar effects between radicals and substrates. We herein disclose that when irradiated by visible light, bromine can behave as a polarity-reversal catalyst. Hydroacylation of vinyl arenes, a three-component cascade transformation and deuteration of aldehydes were each achieved in a metal-free manner without initiators by using inexpensive N-bromosuccinimide as the precatalyst. Light is essential to generate and maintain the active bromine radical during the reaction process. Another key to success is that HBr can behave as an effective hydrogen donor to turn over the catalytic cycles.

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Using bromine as a polarity-reversal catalyst to generate acyl radicals

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Additive- and metal-free, atom- and step-economic, and operationally simple process

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Using constant light-irradiation to induce and maintain bromine radicals

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Access carbonyl compounds and deuterated aldehydes with wide substrate scope