Solid-phase combinatorial synthesis of polyisoxazolines: A two-reaction iterative protocol

Starting from a polymer-bound olefin, iterative application of nitrile oxide 1,3-dipolar cycloaddition and selenide oxidation/elimination steps were employed to deliver a polymer-bound triisoxazoline that can be liberated from the resin by transesterification. When four nitroseleno ethers (2-5) and four capping nitroalkanes (6-9) were employed, a triisoxazoline library (V) of 64 positional isomers was obtained by three iterative applications of these two reactions. The tactical flexibility of this strategy for preparing small polyfunctional oligomers is particularly attractive in that each subunit addition proceeds via a C-C bond-forming step.