Photoredox-catalyzed radical-radical cross coupling of ketyl radicals with unstabilized primary alkyl radicals.

Herein, a novel protocol dealing with the preparation of sterically hindered alcohols has been successfully developed via radical-radical coupling reactions enabled by mild and redox-neutral photocatalysis. With alkylsilicates as the radical precursors, a range of primary alkyl radicals bearing various functional groups could couple with a range of phthalimides and activated ketones.

α-Arylsulfonyloxyacrylates: attractive O-centered electrophiles for synthesis of α-substituted acrylates via Pd-catalysed Suzuki reactions.

We herein report α-arylsulfonyloxyacrylates as a kind of useful and attractive O-centered electrophiles for Suzuki cross-coupling reactions. A range of α-(hetero)aryl substituted acrylates has been prepared via the palladium-catalysed C-C cross-coupling reactions between potassium (hetero)aryltrifluoroborates and α-arylsulfonyloxyacrylates. Moreover, α-arylsulfonyloxyacrylate could also react with B-alkyl-9-BBN to produce α-alkyl substituted acrylates. The synthetic application of this new method was demonstrated by the preparation of the intermediate for synthesis of retinoid X receptors-selective retinoids. These Suzuki reaction-based protocols feature broad substrate scope, generality, and mild reaction conditions.

Diversified access to di- and trisubstituted allenes via nickel-catalysed reactions of 1,3-enynes with alkyl N-hydroxyphthalimide esters.

Herein, a new nickel-catalysed protocol for the preparation of di- and trisubstituted allenes has been successfully developed via the reactions of 1,3-enynes with alkyl N-hydroxyphthalimide esters. The new method based on a reductive radical-polar crossover (RPC) process features broad substrate scope, wide functional group tolerance, and a simple catalyst system. The late-stage allenylation of drugs has also been illustrated.

Access to functionalized alkynylcyclopropanes via reductive radical-polar crossover-based reactions of 1,3-enynes with alkyl radicals.

Herein, using a single-electron-transfer reduction-based radical-polar crossover process as a strategy, protocols dealing with the preparation of functionalized alkynylcyclopropanes have been successfully developed via the reactions of 1,3-enynes with alkyl radicals. In addition to redox-neutral photocatalysis, nickel catalysis with zinc as the reductant is also an alternative to enable reactions of 1,3-enynes with redox-active N-hydroxyphthalimide esters. The synthetic application of alkynylcyclopropane has also been demonstrated.

Modular access to 1,2-allenyl ketones based on a photoredox-catalysed radical-polar crossover process.

Herein, a new protocol dealing with the preparation of 1,2-allenyl ketones has been successfully developed via the reactions of enynes with radicals enabled by dual photoredox/copper catalysis. Based on the results of a deuteration experiment and the competition reaction between cyclopropanation and allenation, the mechanism based on a photoredox-neutral-catalysed radical-polar crossover process has been proposed. Synthetic applications of allenes have also been demonstrated.

Radical trifluoromethylation.

The trifluoromethyl group plays an increasingly important role in pharmaceuticals, agrochemicals and materials. This tutorial describes recent advances in trifluoromethylation of carbon-centered radical intermediates.

Cobalt-Catalyzed Markovnikov-Selective Radical Hydroacylation of Unactivated Alkenes with Acylphosphonates.

Acylphosphonates having the 5,5-dimethyl-1,3,2-dioxophosphinanyl skeleton are developed as efficient intermolecular radical acylation reagents, which enable the cobalt-catalyzed Markovnikov hydroacylation of unactivated alkenes at room temperature under mild conditions. The protocol exhibits broad substrate scope and wide functional group compatibility, providing branched ketones in satisfactory yields. A mechanism involving the Co-H mediated hydrogen atom transfer and subsequent trapping of alkyl radicals by acylphosphonates is proposed.

Copper-Catalyzed Ring-Opening 1,3-Aminotrifluoromethylation of Arylcyclopropanes.

The copper-catalyzed reaction of arylcyclopropanes, N-fluorobis(arenesulfonyl)imides, and (bpy)Zn(CF3)2 (bpy = 2,2'-bipyridine) at room temperature affords the corresponding ring-opening 1,3-aminotrifluoromethylation products in satisfactory yields. The protocol is highly regioselective, providing a convenient entry to γ-trifluoromethylated amines. A mechanism involving the trifluoromethylation of benzyl radicals is proposed.

Pd-Catalysed Suzuki coupling of α-bromoethenylphosphonates with organotrifluoroborates: a general protocol for the synthesis of terminal α-substituted vinylphosphonates.

A general and robust protocol for the synthesis of terminal α-substituted vinylphosphonates via Suzuki coupling of α-bromovinylphosphonates with organotrifluoroborates has been successfully developed. This method features a broad substrate scope, great functional group compatibilities, and easy scale-up ability. In addition to easy access of nucleophiles, a straightforward synthesis of electrophiles was also realized with diethyl α-bromoethenylphosphonate as the starting material. With a combination of Pd2(dba)3/SPhos as the catalyst, a range of α-alkyl, aryl, heteroaryl, and alkynyl substituted ethenylphosphonates could be nicely accessed under mild conditions. As a synthetic application, the terminal vinylphosphonate was utilized as an effective Michael acceptor in the visible-light-promoted Giese reaction.

Applications of α-phosphonovinyl tosylates in the synthesis of α-arylethenylphosphonates via Suzuki-Miyaura cross-coupling reactions.

It has been demonstrated for the first time that α-phosphonovinyl tosylates could efficiently couple with a range of arylboronic acids to access α-arylethenylphosphonates. The unprecedented procedure exhibits excellent functional group tolerance, giving the terminal vinylphosphonates in good to excellent isolated yields (60-99%) under mild reaction conditions.

Platinum-catalysed aerobic 1,2-aminooxygenation of alkenes.

Platinum(II) salts in combination with copper salts and molecular oxygen catalyse an unprecedented intramolecular transfer of heteroatoms to alkenes to yield aminooxygenation products under sustainable conditions.

Synthesis of enol lactones via Cu(I)-catalyzed intramolecular O-vinylation of carboxylic acids.

With the catalysis of CuI/trans-N,N'-dimethylcyclohexane-1,2-diamine, a number of carboxylic acids underwent efficient intramolecular O-vinylation with vinyl bromides leading to the synthesis of the corresponding five- and six-membered enol lactones. The same catalytic system also led to the efficient cycloisomerization of alkynoic acids.

"Ligand-free" CuI-catalyzed highly efficient intramolecular S-vinylation of thiols with vinyl chlorides and bromides.

With CuI as the catalyst and K(3)PO(4) x 3 H(2)O as the base, highly efficient intramolecular S-vinylation of thiols with vinyl chlorides or bromides was successfully implemented without the help of an additional ligand. Moreover, the competition experiments revealed that the 4-exo cyclization is fundamentally preferred over other modes (5-exo, 6-exo, and 6-endo) of cyclization.

O-arylation versus C-arylation: copper-catalyzed intramolecular coupling of aryl bromides with 1,3-dicarbonyls.

The copper-catalyzed intramolecular coupling of aryl bromides with 1,3-dicarbonyls via a six-membered ring closure was examined. With CuI (10 mol %) as the catalyst, N,N'-dimethylethylenediamine as the ligand, and Cs2CO3 as the base, the reactions of alpha-(2-bromobenzyl)-beta-keto esters in THF at refluxing temperature afforded the corresponding substituted 4H-1-benzopyrans in high yields via O-arylation. On the other hand, the reactions of delta-(2-bromophenyl)-beta-keto esters in refluxing dioxane led to the formation of 3,4-dihydronaphthalen-2(1H)-one derivatives via C-arylation.

CuI-catalyzed intramolecular O-vinylation of carbonyl compounds.

The first copper-catalyzed intramolecular O-vinylation of carbonyl compounds with vinyl bromides was reported, among which the efficient formation of 5-, 6- and even 7-membered cyclic alkenyl ethers was achieved with beta-ketoesters as nucleophiles.