Organic Chemistry Using Weakly Electrophilic Salts: Efficient Formation of <i>O</i>,<i>O</i>-Mixed, <i>O</i>,<i>S</i>- and <i>N</i>,<i>O</i>-Acetals
作者:Hiromichi Fujioka、Takashi Okitsu、Takuya Ohnaka、Ruichuan Li、Ozora Kubo、Kazuhisa Okamoto、Yoshinari Sawama、Yasuyuki Kita
DOI:10.1021/jo071187g
日期:2007.10.1
A mild and efficient method for the preparation of O,O-mixed, O,S- and N,O-acetals from symmetrical O,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 then occurred and many acid-labile functional groups could remain intact.