Cyclic alkenes, diastereoselective epoxidations

If an alkene has a hydroxyl (or other functional group capable of donating a proton in a hydrogen bonding interaction) in the allylic position, that group can affect the stereochemistry of the epoxide product. For example, reaction of cyclic allylic alcohols produces a 10 1 ratio of product with the epoxide cis to the alcohol fimction (equation 9.55) relative to the trans product. This diastereoselectivity has been attributed to hydrc en bonding in the transition structure for the epoxidation (Figure... 

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