A variety of substituted benzo[b]furans are readily prepared in good to excellent yields under the mild reaction conditions from o-(1-alkynylphenoxy)-1-phenylethanone under phase-transfer catalysis (PTC). This methodology accommodates simple experimental operations, inexpensive and environmentally benign catalysts, metal catalyst-free conditions, facile reagents and the possibility to conduct large-scale
在相转移催化(PTC)下,由邻-(1-炔基苯氧基)-1-苯基乙酮在温和的反应条件下,可以容易地以良好的产率或优异的产率制备各种取代的苯并[ b ]呋喃。该方法学适用于简单的实验操作,廉价且对环境无害的催化剂,无金属催化剂的条件,简便的试剂以及进行大规模制备的可能性。通过整体结构异构化发展碳-碳键形成过程代表了最经济的方法。
Phosphazene base-catalyzed intramolecular cyclization for efficient synthesis of benzofurans via carbon–carbon bond formation
作者:Chikashi Kanazawa、Kengo Goto、Masahiro Terada
DOI:10.1039/b913588j
日期:——
An organic superbase, phosphazene P4-(t)Bu, functioned as an active catalyst for intramolecularcyclization of o-alkynylphenyl ethers via carbon-carbon bond formation to provide an efficient synthetic method for 2,3-disubstituted benzofurans derivatives under mild reaction conditions without the need for a metal catalyst.
The regioselective cyclization/dehydration sequence of ortho diketo phenoxyethers induced by DBU has been explored. The results demonstrated a high degree of selectivity with preference for 6-exo-trig cyclization leading to the formation of gamma-benzopyranone derivatives in good yield. (C) 2013 Elsevier Ltd. All rights reserved.