Ultrasound-assisted one-pot,three-component synthesis of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridine]-2,6′(1′H)-diones in water

A simple, facile, efficient and three-component procedure for the synthesis of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridine]-2,6′(1′H)-diones by the reaction of 4-hydroxycumarin, isatins and 1H-pyrazol-5-amines in water under ultrasonic irradiation is reported. The advantages of this method are the use of an inexpensive and readily available catalyst, easy work-up, good yields, and the use of water as a solvent that is considered to be relatively environmentally benign.     

Highly Efficient Construction of Bisspirooxindoles Containing Vicinal Spirocenters through an Organocatalytic Modified Feist–Bénary Reaction

We have developed an organocatalytic modified Feist–Bénary reaction of cyclic dicarbonyl compounds, isatins and cyclic α‐bromo dicarbonyl compounds. This method affords bisspirooxindole‐fused dihydrofurans containing two vicinal spiro centers. To the best of our knowledge, employing cyclic α‐halo dicarbonyl compounds for the synthesis of bisspirooxindole‐fused dihydrofurans has not been previously reported.     

An Efficient and Rapid Approach to Quinolines via Friedländer Synthesis Catalyzed by Silica Gel Supported Sodium Hydrogen Sulfate Under Solvent-Free Conditions

Summary. A simple and efficient method for the synthesis of quinolines and polycyclic quinolines using silica gel supported sodium hydrogen sulfate as reusable eco-friendly catalyst via Friedl?nder annulation under solvent-free conditions is described.     

InCl3-catalyzed efficient synthesis of spiro-perimidine derivatives

InCl₃ was found to be a mild and effective catalyst for the simple and efficient synthesis of spiro-perimidine derivatives by the reaction of naphthalene-1,8-diamine and active carbonyl compounds in water at room temperature. This protocol includes some important aspects like the use of water as a “green” reaction medium, good yielding of products and mild reaction conditions.     

A reexamination of Biginelli-like multicomponent condensation reaction: One-pot regioselective synthesis of spiro heterobicyclic rings

A pseudo four-component reaction is described, leading to the efficient regioselective synthesis of sigma symmetric spiro heterobicyclic rings using aldehydes and urea in the presence of cyclic beta-diester or beta-diamides such as Meldrum's acid or barbituric acid derivatives. The reaction needs no added catalyst and proceeds solvent-free conditions at 80 degrees C.