The Claisen rearrangement of allyl phenyl ethers with exceptionally bulky, oxygenophilic methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide) (reagent A) is found to exhibit an unusual behavior not observable in the ordinary thermal and Lewis acid-induced rearrangement.
Bismuth Triflate Catalyzed [1,3] Rearrangement of Aryl 3-Methylbut-2-enyl Ethers
作者:Thierry Ollevier、Topwe Mwene-Mbeja
DOI:10.1055/s-2006-950326
日期:2006.12
An efficient bismuth triflate catalyzed [1,3] rearrangement of aryl 3-methylbut-2-enyl ethers has been developed. The reaction proceeds rapidly and affords the corresponding para- and ortho-prenylated phenols and naphthols in moderate to good yields (up to 86%). ortho-Prenylphenols are immediately cyclized under the reaction conditions to the corresponding chroman derivatives.
Allyl aryl ethers undergo accelerated Claisen and [1,3] rearrangements in the presence of a mixture of trialkylalanes and water or aluminoxanes. The ratio of ortho-, meta-, and para-Claisen products depends to a large extent on the presence of water and to a much lesser extent on the nature of the alane.
The reaction of 1- or 2-naphthol with allylic halides (1-chloro-3-methyl-2-butene, 1-chloro-3,7-dimethyl-2,6-octadiene, trans-1-chloro-2-butene and trans-1-chloro-2-hexene) in the presence of metallic sodium gave naphthols having the corresponding allylic group selectively.