Thermolysis of 2-(N-acylamino)benzyl methyl ethers, in the presence of an acid catalyst and triphenylphosphine, or 2-(N-acylamino)benzylphosphonium salts is found to serve as a novel method for indole formation, in particular for the synthesis of 2-trifluoromethylindoles. The reaction of the benzyl methyl ethers is suggested to involve a phosphonium intermediate, which thermally decomposes to the indoles.
A Facile and Versatile Synthesis of 2-Substituted Tryptophans as<i>N</i>
<sup>α</sup>-<i>tert</i>- Butyloxycarbonyl Derivatives
作者:J. P. Li、Kenneth A. Newlander、Tobias O. Yellin
DOI:10.1055/s-1988-27471
日期:——
Diels-Alder type cycloaddition between 2-substituted indoles and ethyl α-nitrosoacrylate followed by reduction affords 2-substituted tryptophan esters. N-Protection followed by saponification furnishes the corresponding N α-protected 2-substituted tryptophans suitable for peptide synthesis. The preparation of a number of 2-substituted indoles by modified Madelung synthesis is also described.