Brønsted-Acid Catalyzed Diastereo- and Enantioselective Synthesis of Spiroisoindolinones from Enamides.

A highly stereoselective Brønsted-acid catalyzed synthesis of densely substituted spiroisoindolinones from enamides and 3-hydroxy-isoindolinones is described. With simple Brønsted-acids, such as para-toluene sulfonic acid, spiroisoindolinones with three contiguous stereogenic centers are formed in high yields (up to 97 %) and diastereoselectivities (up to >98 : <2 : 0 : 0 dr) under mild reaction conditions. With the use of a chiral phosphoric acid catalyst, a diastereo- and enantioselective synthesis of the corresponding spiroisoindolinones was achieved.

Brønsted Acid-Catalyzed Diastereoselective Synthesis of Spiroisoindolinones from Enamides.

A highly diastereoselective synthesis of spiroisoindolinones from enamides and 3-hydroxy-isoindolinones is reported. The reaction proceeds rapidly in the presence of -toluenesulfonic acid as a Brønsted acid catalyst and affords a variety of densely substituted spiroisoindolinones with three contiguous stereogenic centers in high yields (≤98%) and diastereoselectivities (up to dr >98:<2:0:0).

Iron(III)-Mediated Oxysulfonylation of Enamides with Sodium and Lithium Sulfinates.

An iron-mediated vicinal difunctionalization of enamides and enecarbamates with sulfinic acid salts and alcohols is described. This reaction proceeds under mild conditions and furnishes the oxysulfonylated products in moderate to excellent yields. Moreover, the direct incorporation of sulfur dioxide into the sulfonylated products via organolithium chemistry has been achieved.