Diastereoselectivity of Additions to Chiral Carbonyl Oxides

The influence of a resident stereocenter on the formation of hydroperoxy acetals from carbonyl oxides is investigated. Addition of either methanol or 2-propanol to 2-phenylpropanal O-oxide proceeds with modest stereoselectivity; addition of a tertiary alcohol proceeds with higher selectivity. Product stereochemistry, which is confirmed by conversion of a functionalized hydroperoxy acetal to a 1, 2-dioxane, is found to derive from nucleophilic attack through a Felkin—Anh type transition state. Trapping of a carbonyl oxide containing a neighboring hydrogen bond donor proceeds with modest selectivity for both syn- and anti-carbonyl oxide isomers. Ozonolysis of a 3- (trialkylstannyl)-1-enol ether proceeds with loss of the stannyl-bearing carbon through the possible intermediacy of a vinyl peroxide.