FeCl3-Catalyzed Highly Diastereoselective Synthesis of Substituted Piperidines and Tetrahydropyrans
摘要:
The eco-friendly and highly diastereoselective synthesis of substituted cis-2,6-piperidines and cis-2,6-tetrahydropyrans is described. The key step of this method is the iron-catalyzed thermodynamic equilibration of 2-alkenyl 6-substituted piperidines and 2-alkenyl 6-substituted tetrahydropyrans allowing the isolation of enriched mixtures of the most stable cis-isomers.
The intramolecular Pd(II)-catalysed carbonylation of aminoalkenitol was used as a keystep in the short racemic syntheses of the ladybird beetle alkaloids calvine and epicalvine. The title compounds have been prepared in 26% overall yield over four steps starting from hexanal and pentenyl bromide.
The eco-friendly and highly diastereoselective synthesis of substituted cis-2,6-piperidines and cis-2,6-tetrahydropyrans is described. The key step of this method is the iron-catalyzed thermodynamic equilibration of 2-alkenyl 6-substituted piperidines and 2-alkenyl 6-substituted tetrahydropyrans allowing the isolation of enriched mixtures of the most stable cis-isomers.