Silver Nanoparticle-Catalyzed Diels−Alder Cycloadditions of 2′-Hydroxychalcones
摘要:
Metal nanoparticles are currently being employed as catalysts for a number of classical chemical transformations. In contrast, identification of novel reactions of nanoparticles, especially toward the synthesis of complex natural products and derivatives, is highly underdeveloped and represents a bourgeoning area in chemical synthesis. Herein, we report silica-supported silver nanoparticles as solid, recyclable catalysts for Diels-Alder cycloadditions of 2'-hydroxychalcones and dienes in high yield and turnover number. The use of silver nanoparticle catalysts is further demonstrated by the total synthesis of the cytotoxic natural product panduratin A employing a highly electron-rich dienophile and Lewis acid sensitive diene.
BF3·OEt2 mediated regioselective deacetylation of polyacetoxyacetophenones and its application in the synthesis of natural products
摘要:
We have developed an efficient method to regioselectively deacetylate polyacetoxyacetophenones using BF(3)center dot OEt(2) in excellent yields and demonstrated the application of the procedure in the synthesis of natural products. (C) 2008 Elsevier Ltd All rights reserved.