Reusable Brønsted Acidic Ionic Liquid Catalyzed Reductive Alkylation of Quinolines to Functionalized Tetrahydroquinolines.

A Brønsted acidic ionic liquid (BAIL)-catalyzed one-pot tandem reduction of quinoline to tetrahydroquinoline (THQ) followed by reductive alkylation by the aldehyde has been demonstrated under mild reaction conditions with a shorter reaction time. This step-economical synthetic approach is suitable for late-stage functionalization of complex bioactive molecules. The reaction is highly chemoselective and tolerates a wide range of reducible-sensitive functional groups.

Triple role of boronic acid as a catalyst in the alkylation of quinoline to functionalized tetrahydroquinoline.

The triple role of arylboronic acid as a catalyst in the alkylation of quinoline to -substituted tetrahydroquinoline with a diaryl motif at the C6-position has been developed. This reaction involves the tandem reduction of quinoline to tetrahydroquinoline, followed by reductive -alkylation with aldehyde to form -alkylated tetrahydroquinoline and subsequent regioselective alkylation at the C6-position using -quinone methides (-QMs) in a one-pot operation. The methodology is compatible with a wide variety of functional groups and is also useful in the late-stage functionalization of pharmaceuticals.

Reductive alkylation of azoarenes to -alkylated hydrazines enabled by hexafluoroisopropanol.

A one-pot tandem approach to -alkyl-,'-diarylhydrazines was developed using a sequence of reduction of azoarene to hydrazoarene followed by reductive alkylation by an aldehyde. The mild reaction conditions suppress - cleaved products and selectively provide trisubstituted hydrazine derivatives. The mechanistic study demonstrates that the iminium formation step is likely to be the rate-limiting step.

Facile synthesis of tetrahydroquinoline containing dithiocarbamate derivatives one-pot sequential multicomponent reaction.

An efficient sequential multi-component method for the synthesis of tetrahydroquinoline containing dithiocarbamates has been developed. This reaction involved a boronic acid-catalysed reduction of quinolines to tertrahydroquinolines, followed by nucleophilic addition reaction with carbon disulphide to form dithiocarbamic acids and subsequent -arylation external base-free Chan-Evans-Lam coupling in a one-pot operation. The methodology is compatible with a wide variety of functional groups and also useful in the late-stage functionalization of pharmaceuticals.