The four-membered oxetane ring has been increasingly exploited for its contrasting behaviors: its influence on physicochemical properties as a stable motif in medicinal chemistry and its propensity to undergo ring-opening reactions as a synthetic intermediate. These applications have driven numerous studies into the synthesis of new oxetane derivatives. This review takes an overview of the literature for the synthesis of oxetane derivatives, concentrating on advances in the last five years up to the end of 2015. These methods are clustered by strategies for preparation of the ring and further derivatization of preformed oxetane-containing building blocks. Examples of the use of oxetanes in medicinal chemistry are reported, including a collation of oxetane derivatives appearing in recent patents for medicinal chemistry applications. Finally, examples of oxetane derivatives in ring-opening and ring-expansion reactions are described.

2-Sulfonyl-oxetanes have been prepared, affording non-planar structures with desirable physicochemical properties for fragment based drug discovery. The oxetane motif was formed by an intramolecular C-C bond formation. The fragments were further functionalised via organometallic intermediates at the intact oxetane and aromatic rings.

2-(Arylsulfonyl)oxetanes have been prepared as new structural motifs of interest for medicinal chemistry. These are designed to fit within fragment space and be suitable for screening in fragment based drug discovery, as well as being suitable for further elaboration or incorporation into drug-like compounds. The oxetane ring is constructed through an efficient C-C bond forming cyclisation which allows the incorporation of a wide range of aryl-sulfonyl groups. Furthermore, biaryl-containing compounds can be accessed through Suzuki-Miyaura coupling from halogenated derivatives. With a number of oxetane containing fragment compounds available, their pH stability was assessed, indicating good half-life values for mono-substituted aryl sulfonyl oxetanes across the pH range (1 to 10). Solubility and metabolic stability data is also reported. Finally, the conformation of the fragments is assessed computationally, providing an indication of possible binding orientations.

Abstract:The synthesis of 2-sulfinyl oxetanes is described by a C-C bond forming cyclisation strategy. Oxetanes bearing electron poor aryl sulfoxides are shown to be viable targets using this strategy. We report investigations into the sulfoxide magnesium exchange on 2-sulfinyl oxetanes, which resulted in products formed via ligand exchange and ligand coupling pathways. The sulfinyl-oxetanes can be readily oxidised to the sulfonyl-oxetanes.

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