Visible-Light-Induced Intramolecular Tandem Cyclization of Unactivated Indoloalkynes for the Synthesis of Sulfonylated and Selenylated Indolo[1,2-a]quinolines

A convenient and efficient visible-light-induced method has been developed for the construction of sulfonated and selenylated indolo[1,2-a]quinolines through sulfonyl or selenyl radical-initiated tandem cyclization of unactivated alkynes with sodium sulfinates or diaryl diselenides under mild conditions. This protocol, which simply utilizes visible light as the safe and eco-friendly energy source and an inexpensive and nontoxic organic dye as a photocatalyst without the aid of an external photocatalyst, provides various sulfonyl- and selenyl-containing indolo[1,2-a]quinolines in moderate to good yields.

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

Quinoline-based sulfonyl derivatives, and especially sulfonamides, are relevant and promising structures for drug design. We have developed a new convenient protocol for the synthesis of 3-sulfonyl-substituted quinolines (sulfonamides and sulfones). The approach is based on a Knoevenagel condensation/aza-Wittig reaction cascade involving o-azidobenzaldehydes and ketosulfonamides or ketosulfones as key building blocks. The protocol is appropriate for both ketosulfonyl reagents and α-sulfonyl-substituted alkyl acetates providing the target quinoline derivatives in good to excellent yields.

Metal-free synthesis of N-sulfonylformamidines via skeletal reconstruction of sulfonyl oximonitriles

We firstly develop an unprecedented domino reaction of sulfonyl oximonitriles with secondary amines to streamline synthesis of N-sulfonylformamidines in decent to high yields under mild reaction conditions.

Synthetic and mechanistic aspects of sulfonyl migrations

Sulfonyl migrations, frequently described as ‘unusual’ or ‘unexpected’, from the last 20 years, including 1,2-, 1,3-, 1,4-, 1,5-, 1,6- and 1,7-sulfonyl shifts, through either radical or polar processes, either inter- or intramolecularly are reviewed.

Metal-free sulfonyl radical-initiated cascade cyclization to access sulfonated indolo[1,2-a]quinolines

A metal-free cascade reaction was developed for the synthesis of indolo[1,2-a]quinoline derivatives from arylsulfonyl hydrazides and 1-(2-(arylethynyl)phenyl)indoles in the presence of TBAI/TBHP.