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).