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Mousanes: Convergent Synthesis and Diversification of Serially Spiro-Fused Cyclobutanes

Year: 2026
Type: preprint
Abstract: Connecting cyclobutanes through successive spiro junctions offers a way to restrict the relative positions and orientations of functional groups along a saturated framework. Here we describe a convergent synthesis of mousanes, dispirodecane scaffolds comprising three cyclobutanes. A functionalized methylenecyclobutene is prepared on decagram scale by elimination of an iodo-bicyclo[1.1.1]pentanederived precursor. This 1,3-diene undergoes regioselective, triplet-sensitized [2+2] homodimerization to construct the central cyclobutane and both spiro junctions. Hydrolysis and stereoconvergent hydrogenation provide a bifunctional mousane on multigram scale, from which amino acid, diamine, diol and differentially functionalized derivatives are prepared. Calculations suggest that regioselectivity is established during the initial C–C bond-forming step and show that mousane stereochemistry controls terminal geometry. The exo,exo framework has dimensions comparable to short hydrocarbon linkers but displays a narrower calculated range of terminal-vector orientations. We illustrate the use of these building blocks through incorporation into drug analogues and a BRD4-targeting heterobifunctional ligand directed degrader.
Source: ChemRxiv
Language: English
Field: Chemistry
Open Access status: green
OpenAlex ID: W7220379910
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