Preparation of seven-membered ring cyclic ethers and 3-alkylidenetetrahydropyrans from the cyclization of oxonium cations derived from unsubstituted and silicon-containing 4-alken-1-ols
Preparation of seven-membered ring cyclic ethers and 3-alkylidenetetrahydropyrans from the cyclization of oxonium cations derived from unsubstituted and silicon-containing 4-alken-1-ols
Dramatic solvent effect is observed during the cyclization of 1. Synthesis of 2 is achieved from the reaction of I with a hexamethylditin-catalyzed palladium complex followed by aldehydes in the presence of TMSOTf in THF, whereas 3 is formed in CH2Cl2. The method described herein is successful with various substrates 1 in good yields and high levels of diastereoselectivity.