Efficient Catalytic Synthesis of Condensed Isoxazole Derivatives via Intramolecular Oxidative Cycloaddition of Aldoximes

The intramolecular oxidative cycloaddition reaction of alkyne- or alkene-tethered aldoximes was catalyzed efficiently by hypervalent iodine(III) species to afford the corresponding polycyclic isoxazole derivatives in up to a 94% yield. The structure of the prepared products was confirmed by various methods, including X-ray crystallography. Mechanistic study demonstrated the crucial role of hydroxy(aryl)iodonium tosylate as a precatalyst, which is generated from 2-iodobenzoic acid and m-chloroperoxybenzoic acid in the presence of a catalytic amount of p-toluenesulfonic acid.

Gold-Catalyzed Cyclization of Ynones Involving cis-Hydrofunctionalizations: Rapid Assembly of C-, O-, or S-Functionalized Pyrroles by a Single Methodology

A gold-catalyzed cyclization of conjugated ynones with various nucleophiles such as indoles, alcohols, and thiols has been developed. The reaction provides a new and efficient protocol for the synthesis of functionalized pyrroles with wide versatility and functional group compatibility. Remarkably, for indolyl, alkoxy, or sulfenyl pyrroles, all could be constructed efficiently by this single methodology. In addition, cis-hydrofunctionalizations of ynones are involved in these reactions.

Electrocatalytic synthesis of heterocycles from biomass-derived furfuryl alcohols

It is very attractive yet underexplored to synthesize heterocyclic moieties pertaining to biologically active molecules from biomass-based starting compounds. Herein, we report an electrocatalytic Achmatowicz reaction for the synthesis of hydropyranones from furfuryl alcohols, which can be readily produced from biomass-derived and industrially available furfural. Taking advantage of photo-induced polymerization of a bipyridyl ligand, we demonstrate the facile preparation of a heterogenized nickel electrocatalyst, which effectively drives the Achmatowicz reaction electrochemically. A suite of characterization techniques and density functional theory computations were performed to aid the understanding of the reaction mechanism. It is rationalized that the unsaturated coordination sphere of nickel sites in our electrocatalyst plays an important role at low applied potential, not only allowing the intimate interaction between the nickel center and furfuryl alcohol but also enabling the transfer of hydroxide from nickel to the bound furfuryl alcohol.

Synthesis of heterocyclic compounds through nucleophilic phosphine catalysis

Nucleophilic phosphine catalysis is a practical and powerful tool for the synthesis of various heterocyclic compounds with the advantages of environmentally friendly, metal-free, and mild reaction conditions. The present report summarizes the construction of four to eight-membered heterocyclic compounds containing nitrogen, oxygen and sulphur atoms through phosphine-catalyzed intramolecular annulations and intermolecular [2+2], [3+2], [4+1], [3+1+1], [5+1], [4+2], [2+2+2], [3+3], [4+3] and [3+2+3] annulations of electron-deficient alkenes, allenes, alkynes and Morita-Baylis-Hillman carbonates.

Synthesis of the heterocyclic core of the D-series GE2270

A straightforward enantiomerically pure synthesis of the heterocyclic core of the D-series GE2270 is reported. The synthetic strategy combines the Hantzsch thiazole's building condensation with a cross-coupling reaction including direct C-H hetarylation to build and connect step-by-step thiazolyl moieties to the 5-bromopicolinate as readily available starting material.

New route to 1,4-oxazepane and 1,4-diazepane derivatives: synthesis from N-propargylamines

N-Propargylamines are one of the most useful and versatile building blocks in organic synthesis that are successfully transformed into many significant N-heterocycles.

Hydrolase-catalyzed asymmetric carbon–carbon bond formation in organic synthesis

This article reviews the hydrolase-catalyzed asymmetric carbon–carbon bond-forming reactions for the preparation of enantiomerically enriched compounds in organic synthesis.