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Proximity Effects of a Traceless Linker on Solid-Phase Olefin Cross-Metathesis
A. L. Garner, K. Koide*
University of Pittsburgh, USA
23 January 2008 (online)
The solid-phase olefin cross-metathesis of the immobilized allyloxirane 1 and cinconine 2 was examined for the case in which the chemical yield was strongly affected by the linker group. Thus, the reaction of 1b, which has a traceless propylcarboxamide linker, with cinconine 2 in the presence of 5 mol% of ruthenium-carbene catalyst and 20 mol% of Ti(O-iPr)4 gave the metathesis product 3 in 60% yield, whereas the reaction with 1a, which has no linker, was not successful to give 3 in less than 20% yield (eq. 1). The polystyrene-supported olefin 1b was prepared from the commercially available trityl alcohol derivatives 4 and the aminomethyl polystyrene resin by the standard amide formation, chlorination with acetyl chloride, and the reaction with alcohol 5 (eq. 2).