Selectfluor-Promoted Intramolecular N-S Bond Formation of α-Carbamoyl Ketene Dithioacetals in the Presence of Water: Synthesis of Multifunctionalized Isothiazolones

Skeletal Editing through Molecular Recombination of 2H-Indazoles to Azo-Linked-Quinazolinones

A new protocol by the combinatory use of two equivalent of indazoles starting material with one being the carbon source via its C3-reactivity and the other, the coupling partner has been developed for the selectfluor-mediated single atom skeletal editing of 2H-indazoles. The azo-linked-2,3-disubstituted quinazolin-4-one derivatives were obtained through a carbon atom insertion between the two nitrogens of the indazole ring and simultaneous oxidation at C3 position of both indazole moieties. Mechanistic investigations reveal that the amidic carbonyl oxygen of the product is derived from water and the reaction proceeds through in-situ generated N-centred indazolone radical intermediate.

Base-Promoted Synthesis of S-Arylisothiazolones via Intramolecular Dehydrative Cyclization of α-Keto-N-acylsulfoximines

A base (Et3N)-promoted synthesis of 1,4-diarylisothiazolones from α-keto-N-acylsulfoximines has been achieved. The reaction proceeds via α-hydrogen abstraction from sulfoximine, followed by an intramolecular nucleophilic attack at the keto carbonyl to form a tert-hydroxy isothiazolone intermediate. The 1,4-substituted isothiazolone is obtained after dehydration via an E1cB path. This one-pot synthesis of isothiazolinones has a broad substrate scope, has a high atom economy, and provides products with good yields. The ΔELUMO-HOMO is calculated using Gaussian 16 at the B3LYP/6-31G(d,p) level of theory.

Iodine-Mediated Oxidative Annulation of β,γ-Unsaturated Hydrazones in Dimethyl Sulfoxide: A Strategy to Build 1,6-Dihydropyridazines and Pyrroles

Simple, commercially available iodine was successfully employed as a highly efficient and chemoselective catalyst for the oxidative annulation of β,γ-unsaturated hydrazones to produce 1,6-dihydropyridazines under mild conditions for the first time. Interestingly, when active β,γ-unsaturated hydrazone compounds containing electron-donating groups, such as furyl, thienyl, and cycloalkyl, were used, pyrroles were obtained. A gram-scale preparation experiment and further derivatization of pyridazines demonstrated the potential applicability of our synthesis method. Experimental studies and density functional theory calculations unveiled the origin of the chemoselectivity determining the formation of different products.

Metal-free and Selectfluor-mediated diverse transformations of 2-alkylthiobenzamides to access 2,3-dihydrobenzothiazin-4-ones, benzoisothiazol-3-ones and 2-alkylthiobenzonitriles

Diverse transformations of 2-alkylthiobenzamides have been established to synthesize 2,3-dihydrobenzothiazin-4-ones, benzoisothiazol-3-ones and 2-alkylthiobenzonitriles in the presence of Selectfluor.

PhB(OH)2-Promoted Electrochemical Sulfuration-Formyloxylation of Styrenes and Selectfluor-Mediated Oxidation-Olefination

We report a PhB(OH)₂-promoted electrochemical sulfuration-formyloxylation reaction of styrenes employing commercially available thiophenols/thiols as thiolating agents. Specifically, metal catalysts and external chemical oxidants are not needed in the reaction for the formation of β-formyloxy sulfides, and these sulfides can be further converted to (E)-vinyl sulfones via the Selectfluor-mediated oxidation-olefination. Notably, on the basis of this electrochemical oxidation strategy, β-hydroxy sulfide, β-formyloxy sulfoxide, β-formyloxy sulfone, and (E)-vinyl sulfoxide can also be easily prepared.