Stereoelectronic effects in ring closure reactions: the 2′-hydroxychalcone – flavanone equilibrium, and related systems

Calcium Chloride catalyzed Intramolecular Oxa Michael addition of 2’-Hydroxychalcone to Flavanone

An efficient cyclization of 2’-hydroxychalcone to flavanone using calcium chloride as a catalyst was developed. The scope of the reaction was studied with substituted 2’-hydroxychalcone and these chalcones was converted into corresponding flavanone in good yield. The merits of this method are inexpensive and easily available catalyst, easy workup procedure, avoid use of toxic solvent

Calcium Chloride faciled Intramolecular Oxa addition of 2’-Hydroxychalcone to Flavanone

Calcium Chloride catalyzed Intramolecular Oxa Michael addition of 2’-Hydroxychalcone to Flavanone

An efficient cyclization of 2’-hydroxychalcone to flavanone using calcium chloride as a catalyst was developed. The scope of the reaction was studied with substituted 2’-hydroxychalcone and these chalcones was converted into corresponding flavanone in good yield. The merits of this method are inexpensive and easily available catalyst, easy workup procedure, avoid use of toxic solvent. 

Microwave-assisted ring closure reactions: Synthesis of 8-substituted xanthine derivatives and related pyrimido- and diazepinopurinediones

BACKGROUND Poly-substituted xanthine derivatives are an important class of compounds in medicinal chemistry. Substitution at the 8-position of the purine ring is generally accessible by ring closure of a carboxamido-substituted uracil precursor. Although several procedures to accomplish this synthetic step have been suggested, it still remains difficult in many cases. RESULTS Ring closure rea...

the evaluation of language related engagment and task related engagment with the purpose of investigating the effect of metatalk and task typology

abstract while task-based instruction is considered as the most effective way to learn a language in the related literature, it is oversimplified on various grounds. different variables may affect how students are engaged with not only the language but also with the task itself. the present study was conducted to investigate language and task related engagement on the basis of the task typolog...