Reaction of Imines with 5,5‐Dimethyl‐1, 3‐cyclohexandione

Uncatalyzed Synthesis of Unsymmetrical Indole-substituted Methane Derivatives via One-pot Multicomponent Reactions under Solvent-free Conditions

Abstract:

For the first time, one-pot multicomponent reactions containing indole, aromatic aldehydes, and dimedone have been achieved in the absence of a catalyst under solvent-free conditions. A class of unsymmetrical indole-substituted methane derivatives and symmetrical diindolylmethanes has been synthesized through this green organic synthetic method. Based on experimental results, a reasonable mechanism for this condensation is emphasized here.

An efficient synthesis of 1,8-dioxo-octahydro-xanthene derivatives promoted by a room temperature ionic liquid at ambient conditions under ultrasound irradiation

The condensation reaction involving an aldehyde and diketone was efficiently promoted by the Ionic liquid, [Hbim]BF(4) (IL) as a reaction medium with methanol as co-solvent at ambient temperature under ultrasonic irradiation to afford the corresponding 1,8-dioxo-octahydro-xanthene (xanthene) derivatives in excellent yields. The advantages of this method include among others the use of a recyclable, non-volatile ionic liquid, which promotes this protocol under ambient temperature without the requirement of any added catalyst. The reaction times and yields are compared with p-TSA catalyzed synthesis of xanthenes under thermal conditions, which is also reported for the first time under our reaction conditions.