Palladium-Catalyzed Sequential C(<i>sp</i>
<sup>2</sup>
)-H Alkynylation/Annulation of 2-Phenylphenols with Haloalkynes Using Phenolic Hydroxyl as the Traceless Directing Group
An efficient, palladium(II)‐catalyzed, C(sp2)‐H alkynylation/annulation of 2‐phenylphenols with haloalkynes for the synthesis of substituted 6‐methylene‐6H‐dibenzo[b,d]pyrans is reported. This protocol features a traceless directing group strategy, unique regioselectivity and mild reaction conditions. Significantly, preliminary mechanistic studies suggest that the sequential C(sp2)‐H alkynylation and