Synlett 2016; 27(16): 2301-2313
DOI: 10.1055/s-0035-1561470
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© Georg Thieme Verlag Stuttgart · New York

Synthesis of Spirocyclic and Fused Cyclic Compounds by Transition-Metal-Catalyzed Intramolecular Friedel–Crafts-Type Reactions of Phenol Derivatives

Tetsuhiro Nemoto*
a   Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260-8675, Japan
b   Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan   Email: tnemoto@faculty.chiba-u.jp
,
Yasumasa Hamada
a   Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260-8675, Japan
› Author Affiliations
Further Information

Publication History

Received: 13 April 2016

Accepted after revision: 09 May 2016

Publication Date:
25 July 2016 (online)


Abstract

This account describes the development of novel dearomatization reactions of phenols using transition-metal-catalyzed ipso-Friedel–Crafts-type processes. In general, phenols function as O-nucleo­philes in transition-metal-catalyzed allylic substitution reactions, providing the corresponding aryl ethers. We found that, however, an intramolecular ipso-Friedel–Crafts allylic alkylation of phenols proceeded smoothly in the presence of a palladium catalyst, producing various spiro[4.5]cyclohexadienone derivatives. This finding led us to launch detailed investigations into this type of reaction. Pd-catalyzed intramolecular Friedel–Crafts allylic alkylation of phenols was next examined to synthesize 10-vinyl 9,10-dihydrophenanthrene derivatives. This reaction was successfully extended to a catalytic asymmetric process. We also developed a novel synthetic method for spiro[5.5]cyclohexadienones based on a Pd-catalyzed intramolecular ipso-Friedel–Crafts-type addition of phenols to η3-propargylpalladium(II) intermediates. Mechanistic studies revealed that the present reaction proceeds through a rearomatization-assisted oxidative addition. Moreover, a Au-catalyzed intramolecular ipso-Friedel–Crafts alkenylation of phenols with a terminal alkyne is discussed.

1 Introduction

2 Pd-Catalyzed Intramolecular Friedel–Crafts Allylic Alkylation of Phenols

2.1 Synthesis of Spirocyclohexadienone Derivatives by Pd-Catalyzed Intramolecular ipso-Friedel–Crafts Allylic Alkylation of Phenols

2.2 Mechanistic Considerations

2.3 Application to Cascade Reaction Processes

2.4 Asymmetric Synthesis of Dihydrophenanthrene Derivatives by Pd-Catalyzed Asymmetric Intramolecular Friedel–Crafts Allylic Alkylation of Phenols

3 Dearomatization of Phenols by Activation of Propargyl Carbonates with a Pd Catalyst

4 Au-Catalyzed Intramolecular ipso-Friedel–Crafts Alkenylation of Phenols

5 Summary and Outlook