Chiral and specialty building blocks

Single-handed (enantiopure) molecules such as amino alcohols, chiral amines and lactones used to build drugs and modern agrochemicals; made by resolution, asymmetric catalysis or enzymes.

Fine chemicals · Other fine chemicals · No. 102

• Product family
• not published
• HS 2922, 2932

Many drug molecules come in left- and right-handed forms, and the wrong hand can be useless or even harmful.

Chart: Illustration: Chiral and specialty building blocks

Where it comes from

Chart: Map of where it comes from

Handedness comes from nature's chiral pool, from metal catalysts used at 0.001-0.1 mol%, from enzymes, or by separating a mixture, which needs at least 2 t of racemate per tonne.

Three things to know

1. Since the FDA's 1992 policy, regulators expect new drugs to be developed as single enantiomers, so each stereocentre needs a chiral source or step.
2. Single-isomer agrochemicals can halve the dose, as when S-metolachlor replaced metolachlor; agrochemicals are 12% of demand.
3. Merck and Codexis replaced a rhodium step in sitagliptin with an engineered enzyme, cutting total waste by 19%.

The journey

1. 1 Chiral sourceSugars, amino acids, tartaric or lactic acid
2. 2 Set handednessResolution, asymmetric catalysis or enzymes
3. 3 Building blockPurified to 98-99.5% enantiomeric excess
4. 4 Drug synthesisBuilt into APIs and advanced intermediates
5. 5 ProductsMedicines, single-isomer pesticides, menthol

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