CAN induced double ether ring formation: synthesis of trans- and cis-fused tricyclic ethers from 3-oxabicyclo[3.1.0]hexyl sulfides

Abstract

CAN oxidation of 3-oxabicyclo[3.1.0]hexy sulfides 4 and 5 possessing two hydroxy groups in the C-2 and C-4 side chains promoted a double ether ring formation along with a cleavage of the most substituted cyclopropyl bond to give tricyclic ketal adducts 8 and 10, which were converted to trans- and cis-fused tricyclic ethers 9 and 11 with high or moderate stereoselectivity by a TMSOTf-mediated trialkylsilane reduction.