Enantioselective total syntheses of six natural and two proposed meroterpenoids from Psoralea corylifolia

The first enantioselective total syntheses of six natural and two proposed meroterpenoids isolated from Psoralea corylifolia have been achieved in 7-9 steps from 2-methylcyclohexanone. The current synthetic approaches feature a high level of synthetic flexibility, stereodivergent fashion and short synthetic route, thereby providing a potential platform for the preparation of numerous this-type meroterpenoids and their pseudo-natural products.

Synthesis of Cyclohexanones by a Tandem Photocatalyzed Annulation

The rapid synthesis of cyclic scaffolds is of high importance to the chemistry community. Strategies for the convergent synthesis of substituted carbocycles and heterocycles remain underexplored despite the plethora of applications that these cyclic motifs have in the pharmaceutical and materials industries. Reported herein is a tandem carbene and photoredox-catalyzed process for the convergent synthesis of substituted cycloalkanones via a formal [5 + 1] cycloaddition. Featuring two distinct photoredox cycles and a novel α-oxidation of benzylic ketones, this reaction offers a mild approach to construct two contiguous C-C bonds and eliminates the need for strong bases or expensive metal catalysts. The utility of this method is highlighted through various product diversification reactions that allow access to a range of important cyclic scaffolds.

Synthesis of Dihydroxazines and Fluorinated Oxazepanes Using a Hypervalent Fluoroiodine Reagent

Application of a hypervalent fluoroiodane for the regiodivergent synthesis of dihydroxazines and fluorinated oxazepanes from allylaminoethanol was investigated. The reaction was carried out under mild conditions and gave the products in moderate to good yields. The selectivity of this transformation is controlled by the substituents of the allylaminoethanol.

The organocatalytic enantiodivergent fluorination of β-ketodiaryl-phosphine oxides for the construction of carbon-fluorine quaternary stereocenters

Commercially available cinchona alkaloids that can catalyze the enantiodivergent fluorination of β-ketodiarylphosphine oxides were developed to construct carbon-fluorine quaternary stereocenters. This protocol features a wide scope of substrates and excellent enantioselectivities, and it is scalable.

Transition-Metal-Free Site-Selective γ-C(sp2)-H Monoiodination of Arenes Directed by an Aliphatic Keto Group

A general γ-C(sp²)-H iodination method directed by an aliphatic keto group has been developed under transition-metal-free conditions for the first time, generating iodoarenes in good to excellent yields with excellent site selectivity. This protocol features a wide range of aryl-substituted ketones, short reaction times, mild reaction conditions, and scalable synthetic procedures. A possible reaction mechanism was also proposed based on several control experiments.

Chemoselective Mono- and Difluorination of 1,3-Dicarbonyl Compounds

By altering the amount of Selectfluor, the highly selective mono- and difluorination of 1,3-dicarbonyl compounds has been achieved, affording a variety of 2-fluoro- and 2,2-difluoro-1,3-dicarbonyl compounds in good to excellent yields. The reaction can be readily performed in aqueous media without any catalyst and base, which features practical and convenient fluorination. Importantly, a gram-scale reaction, transformation of 2-fluoro-1,3-diphenylpropane-1,3-dione to 4-fluoro-1,3,5-triphenyl-1H-pyrazole, and chlorination and bromination of 1,3-dicarbonyl compounds are realized to further exhibit its synthetic utility.

Transition-metal-free α-arylation of nitroketones with diaryliodonium salts for the synthesis of tertiary α-aryl, α-nitro ketones

Transition-metal-free α-arylation of α-nitroketones with diaryliodonium salts has been developed for the first time and applied in the synthesis of tiletamine.