DIRECT OXIDATIVE DEPROTECTION OF TETRAHYDROPYRANYL ETHERS USING HEXAMETHYLENETETRAMINE-BROMINE SUPPORTED ONTO SILICA GEL UNDER MICROWAVE IRRADIATION IN SOLVENTLESS SYSTEM

Primary and secondary tetrahydropyranyl ethers (THP ethers) are converted to their corresponding carbonyl compounds efficiently using hexamethylene-tetramine-bromine supported onto silica gel under microwave irradiation in solvent-free conditions.     

A CONVENIENT AND GENERAL SYNTHESIS OF A NOVEL HETEROCYCLIC SYSTEM; 5H-[1,3,4]THIADIAZOLO[2,3-d] [1,2,4]TRIAZIN-5-ONES

Abstract

5H-[1,3,4]Thiadiazolo[2,3-d][1,2,4]triazin-5-ones were synthesized by cyclocondensation of 4-amino-5-mercapto-1,2,4-triazin-3-ones with a variety of carboxylic acids in the presence of phosphorus oxychloride.     

OXIDATIVE DEPROTECTION OF TRIMETHYLSILYL ETHERS WITH HEXAMETHYLENETETRAMINEBROMINE SUPPORTED ONTO SILICA GEL UNDER MICROWAVE IRRADIATION IN SOLVENTLESS SYSTEM

Hexamethylenetetramine-bromine supported onto[3pc] silica gel rapidly converts trimethylsilyl ethers to their corresponding carbonyl compounds under microwave irradiation in solventless system.     

MICROWAVE INDUCED SYNTHESIS OF COUMARINS FROM IN SITU GENERATED STABILIZED PHOSPHORUS YLIDES IN THE PRESENCE OF SILICA GEL POWDER IN SOLVENT-FREE CONDITIONS

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by phenols (1-hydroxynaphthalene, 2-hydroxynaphthalene and 4-bromophenol) leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce corresponding stabilized phosphorus ylides. Microwave was found to catalyze conversion of the stabilized phosphorus ylides to corresponding coumarins in the presence of silica gel powder in solvent-free conditions.     

CARO'S ACID SUPPORTED ON SILICA GEL. PART 7: A VERSATILE REAGENT FOR THE AROMATIZATION OF HANTZSCH 1,4-DIHYROPYRIDINES UNDER NON-AQUEOUS CONDITION AND MICROWAVE IRRADIATION

Efficient oxidation of 1,4-dihydropyridines with Caro's acid on silica gel is achieved under nonaqueous conditions and in a domestic microwave oven. The reactions under microwave irradiation were shorter in duration and higher in yields than the reactions in conventional method, confirming the potentiality of microwave heating in aromatization of Hantzsch 1,4-dihydropyridines.