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Express Lead Library

Release Q1 2018

Express Lead Library (ELL) is an extension of REAL database focusing on novel screening compounds that can be synthesized from the most recently synthesized building blocks. Having the largest building block inventory Enamine continues its expansion. Each month it is enriched with 2 000 new functionalized compounds synthesized in-house. Many of them feature results of our latest research in medchem-driven organic synthesis. Following our doctrine of accelerating drug discovery it’s important to make such chemotypes available for biological screening as soon as possible. We have selected only unusual building blocks that contain at least 2 rings or 7-membeered rings. They are called “core building blocks” as they bear essential molecular complexity rendering novelty to the enumerated compound libraries. All terms of REAL database including synthesis time of 3 weeks with at least 80% success rate are also valid for supplies from ELL. It is recommended as an abundant source of selected novel compounds in Compound Collection Enhancement programs and virtual screening projects.

Core Building Blocks

  • 1 592 New building blocks synthesized in 2015-2017
  • Exclusivity. Over 90% are offered on the market only by Enamine
  • Unique underrepresented structures. The selected building blocks have no close analogues in stock and have not been largely used for library synthesis: > 92 % have less than 25 derivatives in our stock screening collection
  • Essential molecular complexity. Fragment complexity1 > 600

ELL molecules

  • 5.82 Million new compounds
  • Lead-like physicochemical profiles: MW<350, sLogP<3.5 or MW<400, sLogP<3, rotatable bonds<6 (no long chains, <4 open-chain atoms), aromatic rings <3 (at least one heteroaromatic)
  • Balanced diversity, no singletons: 107 572 Murcko frameworks, >5 molecules/framework, 92% has <100 molecules/framework
  • No toxic or unwanted groups. Filters applied: PAINS,2 NO2, CN, ester, triflate, sulfoxide, open-chain sulfide, terminal alkyne, carbamate, Boc-, Fmoc-, aryl/alkyl bromide/iodide, aldehyde, 2-halo pyridine/pyrimidine, oxamides


  1. Nilakantan, R.; Nunn, D. S.; Greenblatt, L.; Walker, G.; Haraki, K.; Mobilio, D. J. Chem. Inf. Model. 2006, 46 (3), 1069.
  2. Baell, J. B.; Holloway, G. A. J. Med. Chem. 2010, 53 (7), 2719.

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