FeCl3·6H2O-catalyzed synthesis of substituted cis-2,6-tetrahydropyrans from ζ-hydroxy allylic derivatives
摘要:
A highly diastereoselective iron-catalyzed synthesis of substituted cis-2,6-tetrahydropyrans from zeta-hydroxy allylic derivatives is described. The FeCl3 center dot 6H(2)O-induced epimerization of the formed 2-alkenyl 6-substituted tetrahydropyrans is the key reaction to account for the high diastereoselectivities observed. (C) 2011 Elsevier Ltd. All rights reserved.
Silica gel was found to efficiently promote the rearrangement of allylic acetates into their most stable regioisomers under microwave irradiation. The reaction is easy to perform and eco-friendly. This method was applied to the metal-free synthesis of 1,3-enynes.
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.