Oxolanes deserve more credit in drug design conversations.
The humble tetrahydrofuran ring is one of the most reliable pieces of scaffolding in a medicinal chemist's toolkit, and it earns that reputation on real merit. This five-membered oxygen heterocycle sits in a useful middle ground. It is saturated enough to add real three-dimensionality to a molecule, and its ring oxygen provides a genuine hydrogen bond acceptor without adding basicity or excess polarity. That balance is likely why the oxolane keeps appearing in approved medicines rather than staying a synthetic chemistry curiosity. The ring also brings a quieter advantage: chemical robustness. Oxolane carries a ring strain of roughly 25 kJ/mol, far below the 106 kJ/mol of oxetane and the 112 kJ/mol of epoxides. That low strain means an oxolane substituent can sit inside a molecule through synthesis and metabolism without the ring-opening liabilities that come with its smaller, more reactive cousins, making it a dependable choice when incorporating an oxygen heterocycle. Also, compared to acyclic ethers, oxolanes provide a more conformationally defined scaffold, which can be advantageous when optimising ligand binding. Terazosin is a good example of how the scaffold can be used, a single tetrahydrofuran-2-yl group attached through a carbonyl to a piperazine ring. Marketed as Hytrin for hypertension and benign prostatic hyperplasia, it is one of thirteen FDA-approved drugs built around a THF core. Gemcitabine shows the same ring used in a completely different way. Instead of hanging off the side of the molecule, the oxolane is the core of the nucleoside itself. The two fluorine atoms influence the preferred sugar conformation and contribute to gemcitabine's unique biochemical properties, ultimately leading to masked chain termination after incorporation into DNA. It remains a standard treatment for pancreatic, non-small cell lung, and ovarian cancers. Are you building saturated oxygen heterocycles into your current chemotypes, or does your scaffold strategy lean more toward nitrogen-based rings? Explore our range of building blocks using the advanced search tools at https://lnkd.in/eVbfw6Ua To read more about Oxolanes in drug discovery, take a look at the following interesting papers: 1. Tetrahydrofuran-Containing Pharmaceuticals: Targets, Pharmacological Activities, and their SAR Studies https://lnkd.in/eJ8sU\_MA 2. Role of Lewis Acids toward the Synthesis of Tetrahydrofuran Motifs: An Update https://lnkd.in/e8bcJRXg
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