Benzyne open-chain additions

The reactions of benzyne are all additions to the formal triple bond of structure 1. The variety of such reactions can be clarified in terms of open-chain additions and cycloadditions, although the isolated products are in many cases derived from secondary decomposition of such primary adducts. The isolation or postulation of cycloadducts in very few cases provides any... 

The ene reaction (Eq. 2) provides a nonpolar mechanism for open-chain addition of benzyne to compounds containing an allylic hydrogen atom. The implied migration of a double bond is not always apparent from the structure of the adduct. The ene reaction frequently occurs in competition with 1, 2-cycloaddition some examples are described in Refs. 1 and 2. 

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