SOLVENT-FREE ORGANIC-REACTIONS ON SILICA-GEL SUPPORTS - FACILE TRANSFORMATION OF EPOXIDES TO BETA-HALOHYDRINS WITH LITHIUM HALIDES

The reaction of epoxides with lithium halides was efficiently promoted on the surface of silica gel in the absence of any solvent to give th e corresponding beta-halohydrins. The reactivity of lithium halides wa s shown to follow the order LiI > LiBr much greater than LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand a similar reaction with alpha,beta-epoxyketones produces the alpha-haloenone derivatives, presumably via halohydin intermediates. The epoxide-opening reaction of (R)-(+)-styrene oxide was also investigated to clarify the stereoch emical features of this reaction. (C) 1998 Elsevier Science Ltd. All r ights reserved.