title: Oxadiazoles in medicinal chemistry.
abstract: Oxadiazoles are five-membered heteroaromatic rings containing two carbons, two nitrogens, and one oxygen atom, and they exist in different regioisomeric forms. Oxadiazoles are frequently occurring motifs in druglike molecules, and they are often used with the intention of being bioisosteric replacements for ester and amide functionalities. The current study presents a systematic comparison of 1,2,4- and 1,3,4-oxadiazole matched pairs in the AstraZeneca compound collection. In virtually all cases, the 1,3,4-oxadiazole isomer shows an order of magnitude lower lipophilicity (log D), as compared to its isomeric partner. Significant differences are also observed with respect to metabolic stability, hERG inhibition, and aqueous solubility, favoring the 1,3,4-oxadiazole isomers. The difference in profile between the 1,2,4 and 1,3,4 regioisomers can be rationalized by their intrinsically different charge distributions (e.g., dipole moments). To facilitate the use of these heteroaromatic rings, novel synthetic routes for ready access of a broad spectrum of 1,3,4-oxadiazoles, under mild conditions, are described.
authors.affiliation: AstraZeneca R&D Mölndal, S-431 83 Mölndal, Sweden. jonas.bostrom@astrazeneca.com
authors.forename: Jonas
authors.initials: J
authors.lastname: Boström
authors.forename: Anders
authors.initials: A
authors.lastname: Hogner
authors.forename: Antonio
authors.initials: A
authors.lastname: Llinàs
authors.forename: Eric
authors.initials: E
authors.lastname: Wellner
authors.forename: Alleyn T
authors.initials: AT
authors.lastname: Plowright
mesh_terms: D000818:Animals; D016466:CHO Cells; D003198:Computer Simulation; D006224:Cricetinae; D003412:Cricetulus; D003500:Cyclization; D065607:Cytochrome P-450 Enzyme Inhibitors; D016208:Databases, Factual; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors; D006801:Humans; D066298:In Vitro Techniques; D007536:Isomerism; D008862:Microsomes, Liver / Q000378:metabolism; D010069:Oxadiazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D011789:Quantum Theory; D012995:Solubility; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D010069:Oxadiazoles