Based on torsion angle distributions of frequently occurring substructures, conformation preferences of druglike molecules are presented, accompanied by a review of the relevant literature. First, the relevance of the Cambridge Structural Database (CSD) for drug design is demonstrated by comparing substructures present in compounds entering clinical trials with those found in the CSD and protein-bound ligands in the Protein Data Bank (PDB). Next, we briefly highlight preferred conformations of elementary acyclic systems, followed by a discussion of sulfonamide conformations. Due to their central role in medicinal chemistry, we discuss properties of aryl ring substituents in depth, including biaryl systems and systems of two aryl rings connected by two acyclic bonds. For a subset of torsion motifs, we also compare torsion angle histograms derived from CSD structures with those derived from ligands in the PDB. Furthermore, selected properties of some six-and seven-membered ring systems are discussed. The article closes with a section on attractive sulfuroxygen contacts.

Drugs with prolonged, on-target residence time often show superior efficacy, yet general strategies for optimizing drug-target residence time are lacking. Here, we demonstrate progress toward this elusive goal by targeting a noncatalytic cysteine in Bruton's tyrosine kinase (BTK) with reversible covalent inhibitors. Utilizing an inverted orientation of the cysteine-reactive cyanoacrylamide electrophile, we identified potent and selective BTK inhibitors that demonstrate biochemical residence times spanning from minutes to 7 days. An inverted cyanoacrylamide with prolonged residence time in vivo remained bound to BTK more than 18 hours after clearance from the circulation. The inverted cyanoacrylamide strategy was further utilized to discover fibroblast growth factor receptor (FGFR) kinase inhibitors with residence times of several days, demonstrating generalizability of the approach. Targeting noncatalytic cysteines with inverted cyanoacrylamides may serve as a broadly applicable platform that facilitates “residence time by design”, the ability to modulate and improve the duration of target engagement in vivo.

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Theoretical chemistry Z 0350 The pKBHX Database: Toward a Better Understanding of Hydrogen-Bond Basicity for Medicinal Chemists -[58 refs.]. -(LAURENCE, C.; BRAMELD*, K. A.; GRATON, J.; LE QUESTEL, J.-Y.; RENAULT, E.; J. Med. Chem. 52 (2009) 14, 4073-4086; Roche, Palo Alto, CA 94304, USA; Eng.) -Lindner 43-278

We have used ab initio quantum mechanical (QM) methods to determine the potential energy of pseudorotation for 3,4-dihydroxy-5-methyl-2-(1-pyrollyl)tetrahydrofuran and 4-hydroxy-5-methyl-2-(1-pyrollyl)-tetrahydrofuran, close analogues of 2′-deoxyribose and ribose sugars. The pyrrole is a substitute for the naturally occurring nucleic acid bases: adenine, thymine, guanine, cytosine, and uracil. At the highest calculation level (LMP2/cc-pVTZ(-f)//HF/6-31G**) for 2′-deoxyribose, we find the C2′-endo conformation is the global minimum. The C3′-endo conformation is a local minimum 0.6 kcal/mol higher in energy, and an eastern barrier of 1.6 kcal/mol separates the two minima. Pseudorotation energies of ribose are quite complex and are strongly affected by local orientations of the 2′ and 3′ hydroxyl groups. When the hydroxyl groups are allowed to assume any conformation, the global minimum remains the C2′-endo conformation. The eastern barrier increases slightly to 1.8 kcal/mol, and the C3′-endo local minimum lies 0.6 kcal/mol above the global minimum. Constraining the torsion angle of the C3′ hydroxyl group to -146°, as is found in RNA polymers, results in the C3′-endo conformation becoming the only energy minimum with a C2′-endo conformation 1.9 kcal/mol higher in energy. Bond angles within the pentofuranose ring are correlated to the pseudorotational phase, as is observed by X-ray crystallography and is predicted by pseudorotation theory. Finally, a force field for use in molecular mechanics and dynamics simulations is presented which reproduces the QM potential energies for the 2′-deoxyribose and ribose sugars.