Nature has produced most natural molecules as chiral objects, which means the molecule can come in two enantiomeric forms, each being the mirror image of the other. When a natural product is synthesised in a laboratory, a chiral synthesis means just one form is made, and then is compared with the natural product to see if it matches.
AbstractA straightforward procedure for the synthesis of enantiopure polysubstituted piperidines is reported. It involves the direct generation of chiral non‐racemic oxazolo[3,2‐a]piperidone lactams that already incorporate carbon substituents on the heterocyclic ring and the subsequent removal of the chiral auxiliary. The key step is a cyclocondensation reaction of (R)‐phenylglycinol or other amino alcohols with racemic or prochiral δ‐oxo (di)acid derivatives in highly stereoselective processes involving dynamic kinetic resolution and/or desymmetrization of diastereotopic or enantiotopic ester groups.
The Born theory of optical activity in quantum-mechanical form is simplified with the aid of certain approximations. It leads to a simple expression for the rotatory parameter of an active molecule in terms of the geometrical configuration and the polarizability tensors of its constituent groups. Optical anisotropy of the component groups and inhibited internal rotation are found to play an important role in determining rotatory power. The proposed theory has points of similarity both with the polarizability theories of Gray, de Mallemann, and Boys and also with Kuhn's specialization of Born's classical theory of optical activity. To illustrate its use, the absolute configuration and the specific rotation of d-secondary butyl alcohol are calculated.