Ultrasound promoted selective synthesis of 2-aryl-5,6-dihydro-4H-1,3-oxazines catalyzed by K-10 and KSF montmorillonite clays: a practical procedure under mild and solvent-free conditions

Indium-mediated regioselective synthesis of ketones from arylstannanes under solvent-free ultrasound irradiation

The solvent-free indium-promoted reaction of alkanoyl chlorides with sterically and electronically diverse arylstannanes is a simple and direct method for the regioselective synthesis of primary, secondary and tertiary alkyl aryl ketones in good to excellent isolated yields (42-84%) under mild and neutral conditions. The protocol is also adequate for the synthesis of aryl vinyl ketones. Reaction times are drastically reduced (from 3-32h to 10-70min) under ultrasonic irradiation. Evidences for the involvement of a homolytic aromatic ipso-substitution mechanism, in which indium metal acts as radical initiator, are presented. It is possible the transference of two aryl groups from tin, thus improving effective mass yield, working with diarylstannanes as starting substrates.

One-pot three-component synthesis of pyrano [3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones

An efficient one-pot synthesis of novel pyrano[3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones via three-component condensation of kojic acid, 1-H-pyrazol-5-amines and aldehydes in the presence of a catalytic amount of Zn(OTf)(2) followed by H(2)O(2)-mediated oxidation is reported. Furthermore, the synthesis of 1'H-spiro[indoline-3,4'-pyrano[2,3-b]pyrazolo[3,4-e]pyridine]-2,8'(9'H)-diones were chosen for the library validation.

Facile cleavage of C-C bond: conversion of pyrane derivative to 1,3-oxazin derivative

A cascade reaction that involves a unique C-C bond cleavage has been discovered. This protocol affords an unusual and facile method for the synthesis of 1,3-oxazin derivatives under mild conditions.

Ultrasound promoted clay catalyzed efficient and one pot synthesis of substituted oxindoles

A simple facile, one-pot synthesis of oxindoles in reasonable purity is reported via intramolecular Friedal-Craft cyclization. Clay KSF is an inexpensive, efficient and mild catalyst for the synthesis of substituted oxindoles by the reaction of chloroacetyl chloride and various anilines under the influence of ultrasonic irradiation under solvent-free conditions. The remarkable advantages of this method are the simple experimental procedures, short reaction times, high yields of products, suitability for a wide variety of substituents, and the green aspects through the avoidance of toxic catalyst and solvents.