10.2.6 Corey-Seebach Reaction

Corey-Seebach reaction provides an effective route for the transformation of aldehydes to ketones (Scheme 10). The aldehydes can be readily reacted with thiol using acid catalysis to afford dithioacetal. The acidic hydrogen of the acetal can then be removed by base such n-BuLi and the carbonanion, stabilized by vacant d orbital of sulfur atom, can be alkylated in high yield. The resultant thioketal can be hydrolytically cleaved in the presence of mercury(II) salt.

Mechanism

Scheme 10

Examples

10.2.7 Corey-Nicolaou Macrocyclization

It is one of the popular macrolactonizations in organic synthesis. First, the thioester is formed from the carboxylic group and 2,2'-dipyridyl disulfide at room temperature which on reflux undergoes lactonization (Scheme 11).