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Chiral Building Blocks Selection

In the last decade, development of new drugs increasingly requires the use of chiral building blocks for hit-to-lead optimization, and even on early stages - in search for efficient hit compounds. The main fundamental reason for this lies in the fact that almost all the biological targets are chiral, and the drug-receptor interaction requires strict match of chirality. The formal reason results from strengthening the regulatory guidance for submitting new drug applications in Europe and USA which concern chirality issues. The following citation of the FDA’s “Policy Statement for the Development of new Stereoisomeric Drugs” illustrates this point: “Now that technological advances (large scale chiral separation procedures or asymmetric syntheses) permit production of many single enantiomers on a commercial scale, it is appropriate to consider what FDA's policy with respect to stereoisomeric mixtures should be… Where little difference is observed in activity and disposition of the enantiomers, racemates may be developed. In some situations, development of a single enantiomer is particularly desirable (e.g., where one enantiomer has a toxic or undesirable pharmacologic effect and the other does not).

Therefore, it is not surprising that the market share of single isomer drugs rose to appreciable 35% by the year 2000 (Fig. 1), and continues to increase nowadays.

Fig. 1. Total and single isomer pharmaceutical sales.

Chiral optically pure building blocks have long been considered as less available than non-chiral – hence the widespread common opinion that non-chiral building blocks are more preferable than chiral, especially on early stages of drug development. Enamine would like to refute this opinion by offering a large selection of easily available, optically pure, functionalized chiral building blocks.

The Enamine’s chemists use all the general approaches to obtaining the chiral building blocks – chiral pool compound modification, asymmetric synthesis (including asymmetric catalysis), and large-scale enantioseparation. The latter became possible due to collaboration between Enamine and SiChem, the expert in chromatographic separation of enantiomers on multigram scale. Resolution of enantiomers by crystallization with chiral optically active resolution agents is also used.

All the synthesized chiral building blocks are analysed at Enamine for optical purity using modern chromatographic, NMR and polarimetric techniques. In particular, chromatographic determination of optical purity is possible on Agilent 1100 chromatograph equipped with ChiraDex and Chiralpack chiral stationary phase analytical columns. NMR analysis of chiral amines and alcohols is done using Mosher’s reagent, the carboxylic acids are analysed by NMR in the presence of chiral additives, and finally, many functionalized compounds are analysed with the help of NMR shift reagents.

We also can synthesize chiral building blocks corresponding to your needs using resolution of racemates (by chromatography or crystallization with resolution agents) or by various stereoselective synthetic approaches.

Optically pure compounds of different classes are available (see the examples below for best-sellers and representative examples). The complete updated database of the Enamines’ chiral building blocks with listed amounts and prices is available here. The compounds are ether in stock or can be prepared in agreed amounts in 2-3 weeks.

natural amino acid derivatives (source of chirality – chiral pool)

EN400-14038 EN400-14053 EN400-14057
EN400-14076 EN400-14086 EN400-14126


unnatural amino acids (source of chirality – separation of diastereomers, chiral pool, separation of enantiomers)

EN400-08701 EN400-08703 EN400-12629
EN400-13332 EN400-13243 EN400-12625



EN300-15121 EN400-14564 EN400-14544
EN400-14471 EN400-14527 EN400-14310


diamines (including monoprotected) (source of chirality –asymmetric synthesis, chiral pool)

EN400-13916 EN400-12780 EN400-13915
EN400-14415 EN400-14499  


alcohols (source of chirality – catalytic asymmetric synthesis and enantioseparation)

EN400-14565 EN400-14533 EN400-14518
EN400-14389 EN400-14267 EN400-14217


aminoalcohols, including N- or/and O-protected (source of chirality – asymmetric synthesis and enantioseparation)

EN400-14497 EN400-13917 EN400-13918
EN400-14596 EN400-14598 EN400-14593


epoxides (source of chirality – catalytic asymmetric synthesis)

EN400-14607 EN400-14608 EN400-14578


hydroxyphosphonates and hydroxyaminophosphonates (source of chirality – catalytic asymmetric synthesis)

EN400-14592 EN400-14600 EN400-14582
EN400-14583 EN400-14587 EN400-14580

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