Rhodium(III)-Catalyzed Dearomatizing (3 + 2) Annulation of 2-Alkenylphenols and Alkynes
摘要:
Appropriately substituted 2-alkenylphenols undergo a mild formal [3C+2C] cycloaddition with alkynes when treated with a Rh(III) catalyst and an oxidant. The reaction, which involves the cleavage of the terminal C-H bond of the alkenyl moiety and the dearomatization of the phenol ring, provides a versatile and efficient approach to highly appealing spirocyclic skeletons and occurs with high selectivity.
Synthesis of Spirocyclic Enones by Rhodium-Catalyzed Dearomatizing Oxidative Annulation of 2-Alkenylphenols with Alkynes and Enynes
作者:Szymon Kujawa、Daniel Best、David J. Burns、Hon Wai Lam
DOI:10.1002/chem.201403454
日期:2014.7.7
The dearomatizing oxidative annulation of 2‐alkenylphenols with alkynes and enynes proceeds with high yields and regioselectivities under RhIII catalysis. These reactions are successful using Cu(OAc)2 or air as the stoichiometric oxidant, and provide spirocyclic enones, the basic ring system of which appears in several natural products. Application of this process to the preparation of a highly functionalized
The ring-opening reaction of benzofuran is a highly desirable, yet underdeveloped transformation for the construction of valuable phenol derivatives. Herein, we report a nickel-catalyzed ring-opening transformation of benzofuran with silanes, giving ortho-alkene-, branched/linear alkyl silane-, and alkenyl silane-substituted phenol derivatives selectively. Control experiments and DFT calculations supported