Vinylic oxirane-alkyne substrates

A diastereoselective tandem intramolecular hetero-5 + 2-cycloaddition/Claisen rearrangement of vinylic oxirane-alkyne substrates using a rhodium NHC complex to provide regiospecific and diastereoselective access to [3.1.0] bicyclic products has been reported (Scheme 153). ... 

The [5+2] cycloaddition has been included in several domino processes. For example, Feng and Zhang have recentiy developed a novel, regiospecific, and diastereoselective domino intramolecular hetero-[5+2] cycloaddition-Claisen rearrangement of vinylic oxirane-alkyne substrates 90, which employed the rhodium Af-heterocyclic carbene complex, RhCl(/-Pr)(cod), as catalyst [95]. The process provided the corresponding [3.1.0] bicyclic products 91 in moderate to high yields (47-92%), as shown in Scheme 20.39. The authors have demonstrated the complete chirality transfer by performing the reaction with an enantiomerically enriched... 

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