Intramolecular Benzyne-Phenolate [4+2] Cycloadditions.

An intramolecular benzyne-phenolate [4+2] cycloaddition is reported. Benzyne precursors, having vicinal halogen-sulfonate functionalities, linked with a phenol(ate) by various tether groups undergo efficient intramolecular [4+2] cycloaddition by treatment with either Ph MgLi or nBuLi for halogen-metal exchange to form various benzobarrelenes.

2-Bromo-6-(chlorodiisopropylsilyl)phenyl tosylate as an efficient platform for intramolecular benzyne-diene [4 + 2] cycloaddition.

An intramolecular benzyne-diene [4 + 2] cycloaddition with broad substrate scope has been realized by using a cleavable silicon tether, allowing access to various polycyclic structures. 2-Bromo-6-(chlorodiisopropylsilyl)phenyl tosylate serves as an efficient platform for (1) rapid attachment of various arynophiles to the benzyne precursor a Si-O bond and (2) facile generation of benzyne halogen-metal exchange with PhMgLi.

Aryne-based strategy in the total synthesis of naturally occurring polycyclic compounds.

The total syntheses of polycyclic natural products by exploiting an aryne as the key reactive species are reviewed. A short introduction summarizes the basic reactivities of aryne species as well as the methods for its generation. In the main part, early examples and the recent reports (mainly 2012-present) on the use of arynes in multistep syntheses are described.