Ring-opening meso-oxabicyclic alkenes

Ring-Opening meso-Oxabicyclic Alkenes with Oxygen-Based Nucleophiles... 

The catalytic enantioselective ring opening of oxabicyclic alkenes by carbon-based nucleophiles is a useful method for the simultaneous introduction of multiple stereocentres under high stereocontrol ([70] and references cited therein). Recently, several methods have been developed for ring opening of these meso heterobicyclic compounds employing different soft- and organometallic nucleophiles [71, 72]. 

Among recently described new Pd-catalysed enantioselective reactions, the ring opening of meso oxabicyclic alkenes with dialkyl zinc reagents in the presence of chiral P/P and P/N ligands reported by Tautens el al. constitutes a synthetically outstanding C-C bond-forming desymmetrization reaction. 

Oxabicyclic alkenes other than oxobenzonorbornadiene have been examined as meso-substrates for the asymmetric ring-opening reaction vhth oxygen nucleophiles. Oxabicyclo[2.2.1.]heptenes proved to be less reactive and failed to open under any of the conditions described, probably due to reduced strain vhthin the molecule. To overcome this barrier, a higher reaction temperature and concentration... 

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