Synthetic Studies of C-15 and C-17 Compounds

A new synthesis of 4-methyl-3-phenyl and 3-phenyl-4-styryl coumarins developed by condensing substituted o-hydroxyacetophenones and 2'-hydroxychalcones with phenyl acetic acid or its 4-methoxy derivative in the presence of DCC-DMSO - 2'-Hydroxy- -cinnamylidene acetophenones undergo facile oxidative cyclisation to the corresponding 2-styryl chromone on treatment with potassium iodate-DMSO - A new convenient method for the benzylation of chelated phenolic groups in various substrates developed by using benzyl chloride-acetone-anhydrous potassium carbonate with tetra-n-butylammonium iodide catalyst (quantitative yields) - 2'-Benzyloxy- -cinnamylidene acetophenones were converted to their epoxides,which on treatment with BF3-etherate afforded the corresponding 3-styryl chromones - 2'-Hydroxy- -cinnamylidene acetophenones gave the corresponding 3-hydroxy-2-styryl chromones on treatment with hydrogen peroxide- diethylamine in DMSO-dioxan - In the 13C-NMR spectral studies of 2'-hydroxy- -cinnamylidene acetophenones the four olefinic carbons were assigned diagnostic and definite d values.

Autorentext

Dr. Manasi Singhi did her BSc Hons and MSc Chemistry from St.Stephens College,University of Delhi,India and obtained her PhD from the same University in 1995. She has over 20 years of teaching and research experience.She has published many international research papers in the areas of Synthetic Organic Chemistry and Polymer Nanocomposites.