Synthesis of Dibenzofurans via Palladium-Catalyzed Phenol-Directed C–H Activation/C–O Cyclization
摘要:
A practical, Pd(0)/Pd(II)-catalyzed reaction was developed for phenol-directed C-H activation/C-O cyclization using air as an oxidant. The turnover-limiting step of the process was found to be C-O reductive elimination instead of C-H activation. This reaction can tolerate a variety of functional groups and is complementary to the previous methods for the synthesis of substituted dibenzofurans.
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