Phenanthrene synthesis by iron-catalyzed [4+2] benzannulation between alkyne and biaryl or 2-alkenylphenyl Grignard reagent.

Arimasa Matsumoto, Laurean Ilies, Eiichi Nakamura

Index: J. Am. Chem. Soc. 133(17) , 6557-9, (2011)

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Abstract

The [4+2] benzannulation reaction of internal or terminal alkynes with 2-biaryl, 2-heteroarylphenyl, or 2-alkenylphenyl Grignard reagents in the presence of Fe(acac)(3), 4,4'-di-tert-butyl-2,2'-bipyridyl, and 1,2-dichloro-2-methylpropane takes place at room temperature in 1 h to give 9-substituted or 9,10-disubstituted phenanthrenes and congeners in moderate to excellent yields. The reaction tolerates sensitive functional groups such as bromide and olefin. When applied to a 1,3-diyne, the annulation reaction takes place on both acetylenic moieties to give a bisphenanthrene derivative.© 2011 American Chemical Society