Visible-light enabled room-temperature dealkylative imidation of secondary and tertiary amines promoted by aerobic ruthenium catalysis

A photoredox dealkylative imidation of tertiary and secondary amines with sulfonyl azide facilitated by aerobic ruthenium-catalysis to afford sulfonyl amidine at room temperature is reported.

Facile One-Pot Access to α-Diazo-β-ketosulfones from Sulfonyl Chlorides and α-Haloketones

A convenient one-pot approach to the preparation of α-diazo-β-ketosulfones from sulfonyl chlorides is described. It involves the conversion of the sulfonyl chloride to sodium sulfinate, alkylation of the latter with α-haloketones followed by diazo transfer using the ‘sulfonyl-azide-free’ (‘SAFE’) protocol in aqueous medium. The simple and expedient method relies on readily available starting materials and provides facile access to a wide variety of valuable diazo reagents for organic synthesis.

A facile access to N-sulfonylthioimidates and their use for the transformation to 3,4-dihydroquinazolines

N-sulfonylthioimidates can be synthesized via terminal alkynes, sulfonyl azide, and thiols using a copper catalyst in the presence of 4-dimethylaminopyridine. Subsequently, it can be transformed to crucial pharmacophores of 3,4-dihydroquinazoline.

Synthesis of Sulfonylisoureas via Sulfo-Click Reactions

The synthesis of sulfonylisoureas from thiocarbamates and sulfonyl azides via a new variant of the sulfo-click reaction is reported. Water was found to be the environmentally benign solvent of choice over various other solvents tested, and the use of any additives was not required to obtain complete conversion. The experimentally simple reaction­ tolerates a broad range of electron-donating and electron-withdrawing substituents attached on both the thiocarbamate and the sulfonyl azide, as shown with the synthesis of 27 sulfonylisoureas that were prepared in yields ranging from 34% to 78%.

Practical Application of the Aqueous ‘Sulfonyl-Azide-Free’ (SAFE) Diazo Transfer Protocol to Less α-C–H Acidic Ketones and Esters

The earlier described ‘sulfonyl-azide-free’ (‘SAFE’) protocol for diazo transfer to CH-acidic 1,3-dicarbonyl compounds (and their similarly activated congeners) has been extended to the less reactive monocarbonyl substrates, which previously required a separate activation step. Formylation in situ, followed by the addition of an optimized amount of the ‘SAFE cocktail’ (obtained by mixing sodium azide, potassium carbonate, and m-carboxybenzenesulfonyl chloride in water) led to the formation of the desired diazo compounds, which were isolated by extraction in moderate to excellent yields, and, in most cases, with no need for additional purification.