Construction of Hexahydrophenanthrenes By Rhodium(I)-Catalyzed Cycloisomerization of Benzylallene-Substituted Internal Alkynes through C−H Activation
作者:Yasuaki Kawaguchi、Shigeo Yasuda、Chisato Mukai
DOI:10.1002/anie.201605640
日期:2016.8.22
The treatment of benzylallene‐substituted internal alkynes with [RhCl(CO)2]2 effects a novel cycloisomerization by C(sp2)−H bond activation to produce hexahydrophenanthrene derivatives. The reaction likely proceeds through consecutive formation of a rhodabicyclo[4.3.0] intermediate, σ‐bond metathesis between the C(sp2)−H bond on the benzene ring and the C(sp2)−RhIII bond, and isomerization between
routes have been developed to construct its skeleton. However, synthesis of unsymmetric phenanthrenes remains a challenge. Here, an efficient one-pot tandem reaction for the preparation of phenanthrenes via sequential γ-C(sp2)–H arylation, cationic cyclization, dehydration, and 1,2-migration was developed. A wide range of symmetric and unsymmetric phenanthrenes with diversified functional groups were synthesized