AUTHOR=Li Heng , Hao Wen-Juan , Li Guigen , Tu Shu-Jiang , Jiang Bo 

TITLE=Fe(III)-Catalyzed Bicyclization of Yne-Allenones With Indoles for the Atom-Economic Synthesis of 3-Indolyl Cyclobutarenes

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00599

DOI=10.3389/fchem.2018.00599

ISSN=2296-2646

ABSTRACT=<p>A new Fe(III)-catalyzed bicyclization reaction of yne-allenones with indoles has been established, enabling the direct construction of cyclobuta[<italic>a</italic>]naphthalen-4-ols with an all-carbon quaternary center in good to excellent yields. This reaction was performed by using low-cost FeCl<sub>3</sub> as the catalyst and EtOH as the environmentally benign solvent, providing a green protocol for constructing the cyclobutarene framework with a high degree of atom economy and functional group compatibility. The reaction mechanism was proposed to proceed through a [2 + 2] cycloaddition/1,6-conjugate addition cascade.</p>