Desymmetrization
Desymmetrization in
Examples
Typical substrates are
One example is the conversion of cis-3,5-diacetoxycyclopentene to monoacetate. In this transformation, the plane of symmetry in the precursor is lost, and the product is asymmetric. The desymmetrisation itself is not usually considered useful. The enantioselective desymmetrisation however delivers a useful product. This particular conversion utilizes the enzyme cholinesterase.[3]
In another example, a symmetrical cyclic imide is subjected to asymmetric deprotonation resulting in a chiral product with high enantioselectivity.[4]
Transfer hydrogenation converts benzil (PhC(O)C(O)Ph) into one enantiomer of hydrobenzoin:[5]
- PhC(O)C(O)Ph + 2 H2 → PhCH(OH)CH(OH)Ph
The precursor benzil has C2v symmetry, and the product is C2 symmetric.
Citric acid is also a symmetric molecule that can be desymmetrized by partial methylation.
References
- ^ doi:10.1039/A906269B
- ^ Basic Terminology of Stereochemistry, G.P. Moss Ed. Pure Appl. Chem., Vol. 68, No. 12, pp. 2193-2222, 1996.
- ^ Donald R. Deardorff, Colin Q. Windham, and Chris L. Craney "Enantioselective Hydrolysis of cis-3,5-diacetoxycyclopentene: (1R,4S)-(+)-4-Hydroxy-2-cyclopentenyl Acetate" Organic Syntheses, Coll. Vol. 9, p.487 (1998); Vol. 73, p.25 (1996).
- ^ Takao Ikariya, Shohei Hashiguchi, Kunihiko Murata, and Ryōji Noyori (2005). "Preparation of Optically Active (R,R)-Hydrobenzoin from Benzoin or Benzil". Organic Syntheses: 10
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