Asymmetric Reactions with Oxabicyclic Alkenes

In contrast to the high reactivity of meta- and para-substituted halophenols, ortho-halo-phenols give low yields, even after prolonged reaction times with the [Rh(COD)Cl]2/ 

Third-Generation Catalyst [Rh(PPF-P Bu2)l] with Excess NH4I 

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Rhodium catalysts have also been used with increasing frequency for the allylic etherification of aliphatic alcohols. The chiral 7r-allylrhodium complexes generated from asymmetric ring-opening (ARO) reactions have been shown to react with both aromatic and aliphatic alcohols (Equation (46)).185-188 Mechanistic studies have shown that the reaction proceeds by an oxidative addition of Rh(i) into the oxabicyclic alkene system with retention of configuration, as directed by coordination of the oxygen atom, and subsequent SN2 addition of the oxygen nucleophile. 

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