Organocatalytic Asymmetric Annulation of 1,3-Bis(alkoxycarbonyl)buta-1,3-dienes and Aldehydes

Asymmetric organocatalytic annulation of <i>E</i>/<i>Z</i> isomeric mixtures of bis(alkyl carboxylate)buta-1,3-dienes and aldehydes has been realized via enamine catalysis. In the presence of α,α-diphenyl-2-pyrrolidinemethanol trimethylsilyl ether, excellent stereo- and enantioselectivities were achieved for a broad spectrum of substrates

Stereoselective Synthesis of 3‑Substituted Tetra­hydro­pyrazino­iso­quinolines via Intramolecular Cyclization of Enantiomerically Enriched Dihydro‑2<i>H</i>‑pyrazines

The preparation of 3-substituted tetra­hydro­pyrazino­iso­quinolines using the tributyltin hydride mediated intramolecular radical cyclization of suitably protected 2-substituted 3,4-dihydropyrazines is reported. The compounds are obtained as single enantiomers, as the relative configuration of the new generated stereogenic center is driven by the stereochemistry of the 2-substituted carbon in the starting materials, which is in turn derived from naturally occurring amino acids