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Abstract Substitutional lability of the terminal methoxide ligand on a Zr(IV) substituted polyoxovanadate‐alkoxide (POV‐alkoxide) via protonolysis is presented. Addition of excess water or stoichiometric 2,2,2‐trifluoroethanol results in the exchange of the terminal methoxide ligand for a hydroxide or 2,2,2‐trifluoroethoxide ligand, respectively. The lability of the terminal methoxide ligand at zirconium is leveraged to access a relatively stable terminal peroxide bound to a POV‐alkoxide supported Zr(IV) center, via addition of hydrogen peroxide adducts compatible with organic solvent. Isolation of the terminal peroxide complex allows for investigation into the impact of the sterically protected, electron‐rich POV‐alkoxide support on the activation of hydrogen peroxide at Zr(IV). While the isolated peroxide complex is inactive towards the oxidation of thioethers, the methoxy terminated Zr(IV) functions as a precatalyst for the reaction. Mechanistic analysis reveals electrophilic oxidation conditions with hydrogen peroxide substrates, with a nucleophilic parameter ( ) of 0.09±0.02. In thioether oxidation reactions, selectivity for sulfoxide products (95–99 %) in acetonitrile is observed, suggesting the use of a reduced POV‐alkoxide prevents over‐oxidation of substrate. 

Abstract This manuscript describes a study of diverse reaction outcomes that stem from the ionization ofaza‐alkynyl‐Prins adducts. Experimental results have demonstrated unexpected behavior in the nitrogen‐containing systems compared to the analogous oxygen derivatives derived fromoxa‐Prins/halo‐Nazarov sequences. In‐depth experimental studies and computational analysis revealed an intricate mechanism involving competinghalo‐Nazarov andimino‐Nazarov pathways. These findings further elucidate the reaction chemistry of 3‐halo‐pentadienyl cation intermediates, and expand their utility in synthetic transformations. 

Abstract Typical approaches to heterocycle construction require significant changes in synthetic strategy even for a change as minor as increasing the ring size. The ability to access multiple heterocyclic scaffolds through a common synthetic approach, simply through trivial modification of one reaction component, would enable facile access to diverse libraries of structural analogues of core scaffolds. Here, we show that urea‐derived ligands effectively promote Pd‐mediated chainwalking processes to enable remote heteroannulation for the rapid construction of six‐ and seven‐membered azaheterocycles under essentially identical reaction conditions. This method demonstrates good functional group tolerance and effectively engages sterically hindered substrates. In addition, this reaction is applicable to target‐oriented synthesis, demonstrated through the formal synthesis of antimalarial alkaloid galipinine. 

Previously unobserved (carbamoyl)disulfanyl chlorides were prepared by (i) addition of limiting aromatic secondary amine to (chlorocarbonyl)disulfanyl chloride; (ii) Harris reactions of sulfur dichloride with appropriate O-alkyl N-methyl-N-arylthiocarbamates; and (iii) regiospecific chlorolysis of bis(N-methyl-N-arylcarbamoyl)disulfanes. The newly synthesized unstable species were observed in situ by 1H NMR and were trapped with alkenes, thiocarbamates, and thiols using methods precedented by the chemistry of analogous (carbamoyl)sulfenyl chlorides. Furthermore, each of the trapped products was synthesized by an alternate route, reinforcing conclusions about their structures. While (N-methyl-N-phenylcarbamoyl)disulfanyl chloride was unstable and decomposed quickly or cyclized intramolecularly, introduction of the N,2,6-trimethylphenyl moiety led to significantly improved stability. As part of this study, an interesting, unexpectedly stable 1,2,4-dithiazinone was discovered and its structure was established by X-ray crystallography. The new heterocycle, with its twisted out-of-plane disulfide bond in a six-membered ring, readily donated a sulfur atom to triphenylphosphine; this reaction resulted in the formation of triphenylphosphine sulfide, along with the corresponding highly stable heterocycle in which the single sulfur that remains is part of a planar five-membered ring, fused to a co-planar aryl moiety.