Highly diastereoselective Morita-Baylis-Hillman chemistry: A remote activation effect in the diastereoface selective synthesis of densely functionalized branched cyclic enones from d-glucose

摘要

A highly diastereoselective C-2 alkylation of sugar derived cyclic enone 1 in the presence of diethylaluminium iodide by utilizing Morita-Baylis-Hillman chemistry is reported. While diethylaluminium iodide was found to be a suitable Lewis acid for this transformation, the widely employed TiCl _4 was ineffective. A plausible mechanism, which considered the involvement of a Zimmerman-Traxler type of closed transition state and an orthoester intermediate, has been discussed.