A novel route to synthesis of flavones from salicylaldehyde and acetophenone derivatives

Convenient, facile, and alternate synthesis of medicinally important flavones is reported. The 2-hydroxychalcones derived from condensation between acetophenones and salicylaldehyde, underwent oxidative cyclization on heating in the presence of catalytic iodine, generating diversified flavones under solvent-free conditions. Eleven compounds have been synthesized in good to excellent yields and their mechanism of formation is described.     

Analysis of taxol and major taxoids in Himalayan yew, Taxus wallichiana.

A reversed-phase column liquid chromatography method for the analysis of taxol, 10-deacetylbaccatin III, baccatin IV, 1-hydroxybaccatin I, 2-acetoxybrevifoliol, brevifoliol, 2'-deacetoxydecinnamoyltaxinine J and 2'-deacetoxytaxinine J in yew needles has been developed using a Nova-Pak Phenyl column and a binary gradient profile. The various aspects of analysis such as extraction efficiency, detection limits, reproducibility and peak purity were validated using UV-Vis as well as photodiode array detection.     

Magnetization curves for non-elliptic cylindrical samples in a transverse field

Using recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform interior magnetic field and an assumed set of flux-fronts, solutions of Bean’s critical state model for cylindrical samples with non-elliptic cross-section are presented. Magnetization hysteresis loops for two cross-sections with different aspect ratios are obtained. A comparison with some exact results shows the limitations of this approach.     

New Protocol for Masking and Unmasking Vicinal Hydroxyl and Formyl Groups in 6-Hydroxyarene-1,3-dicarboxaldehydes

A simple and efficient protocol is revealed for the masking and unmasking of an α-hydroxyl benzaldedyde group in aromatic dialdehydes by forming keto-enamine Schiff bases and subsequent unmasking using NaN₃/DMF.     

Iodine-Catalyzed Mild and Efficient Method for the Synthesis of Chalcones

Molecular iodine is found to catalyze the condensation of acetophenones with various aromatic aldehydes to prepare chalcones.     

A new iodine catalyzed regioselective synthesis of xanthene synthons

This Letter describes the iodine catalyzed one-pot regioselective synthesis of p-condensed xanthenes as our key point of transformation, which provides an efficient access to five skeletally diverse scaffolds in excellent yields.