Use of Hindered Silyl Ethers as Protecting Groups for the Non-aldol Aldol Process.

[reaction: see text] Bulky epoxy bis-silyl ethers, e.g., 15, derived from 5-trialkylsilyloxy-2-alken-1-ols by epoxidation and silylation were treated with TMSOTf to afford non-aldol aldol rearrangement products, the 3,5-bis(silyloxy)alkanals, e.g., 16, with little to none of the corresponding tetrahydrofurans.