Diastereoselective Three-Component Vinylogous Mannich Reaction of Nitrogen Heterocycles, Acyl/Sulfonyl Chlorides, and Silyloxyfurans/pyrroles

Abstract

A one-step, 3-component vinylogous Mannich reaction of trimethylsilyloxyfuran or <i>N</i>-protected <i>tert</i>-butyldimethylsilyloxypyrrole with a variety of nitrogen-containing heterocycles in the presence of diverse electrophiles is described. The reaction products were generally obtained in high yields and as a single diastereoisomer having the (<i>R</i>*,<i>R</i>*) relative configuration based on crystallographic studies of several derivatives. Several azaheterocycles were successfully used for this reaction, such as isoquinolines, quinoline, phenanthridine, quinazoline, phthalazine, and β-carboline, and electrophiles included acetyl chloride, methyl chloroformate, methyl chloromalonate, 2-bromobutanoyl chloride, and arylsulfonyl chlorides. The products of the vinylogous Mannich reactions were subjected to further transformations, leading to highly functionalized and stereochemically defined tetracyclic derivatives that are valuable building blocks for the preparation of natural products or medicinal agents