| Abstract
| - A mild and efficient method for the preparation of O,O-mixed, O,S- and N,O-acetals from symmetricalO,O-acetals has been developed. Thus, the treatment of symmetrical O,O-acetals with TESOTf and 2,4,6-collidine formed weakly electrophilic collidinium salts. The addition of nucleophiles, such as an alcohol,lithium thioxide, and sodium azide, to the salts afforded the corresponding O,O-mixed, O,S- and N,O-acetals in good yields. The reaction proceeded under weakly basic conditions. No overreaction thenoccurred and many acid-labile functional groups could remain intact.
|
