Our initial investigations were conducted with Ph3CBF4, an unusual Lewis acid catalyst (Table , Entry 1). We wondered if other Lewis acids were capable of transforming silanol epoxide A into silanoxy-tetrahydrofuran B. Interestingly, with the related catalyst tropylium tetrafluoroborate, the reaction shut down completely (Table , Entry 2). With strong Lewis acids such as Al(OTf)3, Sc(OTf)3, BF3•OEt2, and In(OTf)3, the yield of the rearrangement was comparable to that with Ph3CBF4 (Table , Entries 3-6). With Zn(OTf)2, a markedly weaker Lewis acid, the yield of B was only 10% with starting material accounting for the remaining mass balance (Table ). A solvent screen (See Supporting Information, Additional Optimization Section) revealed that none were better than CH2Cl2.