DIASTEREOSELECTIVITY OF ADDITIONS TO CHIRAL CARBONYL OXIDES

The influence of a resident stereocenter on the formation of hydropero xy acetals from carbonyl oxides is investigated. Addition of either me thanol or 2-propanol to 8-phenylpropanal O-oxide proceeds with modest stereoselectivity; addition of a tertiary alcohol proceeds with higher selectivity. Product stereochemistry, which is confirmed by conversio n 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-car bonyl 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.