One-Pot Reaction Sequence: -Acylation/Pictet-Spengler Reaction/Intramolecular [4 + 2] Cycloaddition/Aromatization in the Synthesis of β-Carboline Alkaloid Analogues.

One-pot synthesis of tetrahydro-β-carbolines, fused with an isoindole core, was proposed starting from maleic anhydride and azomethines easily available from tryptamines and 3-(hetaryl)acroleins. This sequence includes four key steps: an acylation of the aldimine with maleic anhydride, a Pictet-Spengler cyclization, an intramolecular Diels-Alder reaction, and a concluding [1,3]- shift. As a result, six- or seven-nuclear alkaloid-like heterocyclic systems, containing a benzo[1,2]indolizino[8,7-]indole fragment annulated with furan, thiophene, or pyrrole, are formed in a diastereoselective manner.

Domino Three-Component -Acylation/[4 + 2] Cycloaddition/Alder-ene Synthesis of Polysubstituted Benzo[]isoindole-4-carboxylic Acids.

Diversely substituted, partially saturated benzo[]isoindole-4-carboxylic acids were synthesized by a new three-component reaction (3CR) starting from cinnamic amines (3-arylallylamines), maleimides, and maleic anhydride. The process consists of -acylation of the amines by maleic anhydride, intramolecular [4 + 2] cycloaddition in vinylarenes (the IMDAV reaction), and the concluding Alder-ene reaction between Diels-Alder intermediates and maleimides. All of the reaction steps proceed in a highly regio- and stereoselective manner, furnishing five adjacent chiral centers and leading to a single diastereoisomer of the title compound.