Diastereoselective Synthesis of Rauhut-Currier-Type Adducts via an Unexpected α-Addition of α,ß-Unsaturated γ-Butyrolactams to Coumarin Derivatives.

A novel, base-catalyzed and highly diastereoselective direct Michael addition-isomerization sequence is presented for the efficient synthesis of Rauhut-Currier-type adducts. An unexpected α-addition of γ-butyrolactam onto the 3-acyl coumarin derivatives was observed rather than the γ-addition, which is more common. The adducts could further undergo hydrolysis/decarboxylation to generate the products which are equivalent to those obtained by α-addition of γ-butyrolactam onto the corresponding chalcones.

Organocatalytic enantioselective direct vinylogous Michael addition of α,ß-unsaturated γ-butyrolactam to ß-acyl acrylates and 1,2-diacylethylenes.

A highly efficient Michael addition of α,ß-unsaturated γ-butyrolactam to various ß-acyl acrylates and ene-diones to provide synthetically useful compounds was developed. The products were obtained with high diastereo- and enantioselectivities (up to >25:1 dr and 99% ee) containing adjacent tertiary stereocenters.

Chemoselective intramolecular Wittig reactions for the synthesis of oxazoles and benzofurans.

A chemoselective approach was developed for the synthesis of highly functionalized oxazoles and benzofurans using an intramolecular Wittig reaction as the key step. By choosing proper trapping reagent or method of addition of reagents, chemoselectivity can be controlled toward either oxazole or benzofuran derivatives.