meso Compounds: Stepchildren or Favored Children of Stereoselective Synthesis?

• Published in: Angewandte Chemie International Edition 2003-03, Vol.42 (10), p.1096-1109
• Main Author: Hoffmann, Reinhard W.
• Format: Article
• Language: English
• Subjects: asymmetric induction; meso compounds; stereoselective synthesis; synthetic methods
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.200390291

After more than a quarter of a century of development, the methodology of stereoselective synthesis appears to be fully matured. In line with this, the potential that meso compounds offer in stereoselective synthesis is clearly recognized. The use of meso compounds in synthesis is, however, in no way commensurate with this potential, because, ironically, the synthesis of meso compounds in the first place is a problem of stereoselective synthesis. Present‐day methodology does not provide many useful solutions to this problem. This Review therefore addresses the strategies available for the synthesis of more elaborate meso compounds whose stereogenic centers have a distance >1,4 between them. meso Compounds with more than four stereogenic centers are also considered. The criteria used in choosing from several strategies in the synthesis of such compounds are discussed. On first thought, symmetrical molecules should be easier to synthesize than asymmetrical compounds. This does not, however, hold for meso compounds, that is, molecules with a mirror plane (1; σ‐symmetry Tr=triphenylmethyl) or a center of inversion (2; i‐symmetry) and with multiple stereogenic centers. The principal strategies available for the synthesis of such compounds are delineated and illustrated in this review.