In the previous issue, we presented the set of building blocks which had at least one fluorine substituent. This issue continues representation of fluorine-substituted building blocks emphasizing compounds derived from original scaffolds designed by Enamine chemists.

Understanding the importance of the fluoro-organic compounds for the pharmaceutical industry, we put much effort in adapting known and developing new synthetic methodologies allowing introducing fluorine by the use of different fluorine reagents.

The primary structure of a peptide can be formally considered as a oligoethylenediamine molecular platform to which the side chains and carbonyl oxygen atoms are attached through single and double bonds respectively. This backbone is conformationally restrained at the amide bonds and has some rotational degrees of freedom at single C-C and C-N bonds. The later become restricted upon the formation of the secondary structures stabilized by multiple hydrogen bonds. The fragments of 1,3-, 1,4-, 1,5- and 1,6-diamines are found in peptides containing aspargine, glutamine, tryptophane, histidine, lysine and arginine. Apparently some structural, conformational and functional features of peptides can be reproduced by designed derivatives of synthetic conformationally restrained diamines.

This issue of Enamine Product Focus introduces a family of functionalized building blocks called linkers. The term “linker” has been used in medicinal chemistry to define different substances. To avoid ambiguity we will use here the following meaning: a compound is viewed as a linker if it has two or more chemically orthogonal functionalities on an inert, flexible or rigid scaffold. Functional groups could be used to connect (or “link”) fragments responsible for the interaction with biological target – this is applicable both for HTS libraries design and in Fragment-Based Drug Discovery (FBDD). For the latter approach to drug discovery, the design of linkers is particularly critical.