RESUMO
One-pot synthesis of tetrahydro-ß-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]-H shift. As a result, six- or seven-nuclear alkaloid-like heterocyclic systems, containing a benzo[1,2]indolizino[8,7-b]indole fragment annulated with furan, thiophene, or pyrrole, are formed in a diastereoselective manner.
RESUMO
The reactions of 3-acetyl-3-aza-11-oxatricyclo[6.2.1.0(1,6)]undec-9-ene and its 9,10-epoxy derivative with bromine and Ac(2)O/BF(3).OEt(2) under different conditions were studied. Unusual products of Wagner-Meerwein rearrangement bearing the olefin fragment (5-aza-2-oxatricyclo[6.2.1.0(3,9)]undecen-3-enes) were isolated and characterized by X-ray analysis.