Benzylation of arenes through FeCl3-catalyzed Friedel–Crafts reaction via C–O activation of benzyl ether
作者:Bi-Qin Wang、Shi-Kai Xiang、Zuo-Peng Sun、Bing-Tao Guan、Ping Hu、Ke-Qing Zhao、Zhang-Jie Shi
DOI:10.1016/j.tetlet.2008.04.117
日期:2008.6
Various benzyl ethers were converted to benzyl arenes via a FeCl3-catalyzed Friedel–Crafts alkylation reaction under mild condition in good yields. This method also offered a simple and practical approach to synthesize di- or tri-aryl methanes and aryl heteroaryl methanes through the activation of C–O bonds.
The formal total synthesis of camptothecin was achieved via two types of lithiation reactions of pyridine derivatives and a Pd-catalyzed carbonylation of pyridylmethyl methanesulfonates.
The reductive cleavage of aromatic dimethylacetals and ketals, 1, with Li metal in THF at low temperature allows the generation of stable α-alkoxy-α-arylsubstituted carbanions, avoiding the Wittig rearrangement. Reaction of these carbanions with various electrophiles afforded the expected products 2. Further in situ reaction of compounds 2 afforded the products of reductive electrophilic disubstitution
Treatment of benzylmethylether with n-butyl-lithium–tetramethylenediamine in hexane gave benzylic-lithiation, without ortho-lithiation or a Wittig type rearrangement. The benzylic-lithiated benzylmethylether was then allowed to react with benzophenone, 4-methoxybenzophenone, butyl bromide, ethyl phenylacetate, and 4-chlorobenzophenone.