chiral pool

The chiral pool is nature's bargain bin of single-handed molecules. Living things make sugars, amino acids, and terpenes in just one mirror-image form, and these are cheap and abundant, so chemists borrow them as ready-made enantiopure starting materials rather than building handedness from scratch in the lab.

Chirality is the property of a molecule existing as two non-superimposable mirror images, like left and right hands, and getting just one of them is often crucial because the two can behave very differently in the body. Chiral-pool synthesis sidesteps the difficulty of asymmetric reactions by starting from an inexpensive natural product, such as L-proline, D-glucose, or quinine, whose existing stereocenters are carried through the route into the target.

The strength of this strategy, that the handedness comes pre-installed and reliable, is also its limit: you are constrained to the configurations and substitution patterns nature happens to provide, and the wrong enantiomer of a natural building block may be rare or costly. When the chiral pool does not offer what you need, asymmetric synthesis or resolution becomes the alternative.