Microwave-assisted synthesis of substituted tetrahydropyrans catalyzed by ZrCl4 and its application in the asymmetric synthesis of exo- and endo-brevicomin.

The ZrCl4-catalyzed deprotection of 1,3-dioxane/dioxalane and the simultaneous formation of 6-methoxy-substituted tetrahydropyrans proceeded under microwave irradiation in good yield. This synthetic methodology was used for the asymmetric synthesis of (+)-exo- and (+)-endo-brevicomin in 55% overall yield over 4 steps.