Electrophilic Spirocyclization of a 2-Biphenylacetylene via Conformational Fixing within a Hollow-Cage Host

Hiroki Takezawa; Yuya Fujii; Takashi Murase; Makoto Fujita

doi:10.1002/anie.202203970

Electrophilic Spirocyclization of a 2-Biphenylacetylene via Conformational Fixing within a Hollow-Cage Host

Angew Chem Int Ed Engl. 2022 Jun 13;61(24):e202203970. doi: 10.1002/anie.202203970. Epub 2022 Apr 20.

Authors

Hiroki Takezawa¹, Yuya Fujii¹, Takashi Murase², Makoto Fujita^{1

3}

Affiliations

¹ Department of Applied Chemistry, School of Engineering, The University of Tokyo, Mitsui Link Lab Kashiwanoha 1, FS CREATION, 6-6-2 Kashiwanoha, Kashiwa, Chiba, 227-0882, Japan.
² Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata-shi, Yamagata, 990-8560, Japan.
³ Division of Advanced Molecular Science, Institute for Molecular Science (IMS), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.

PMID: 35384218
DOI: 10.1002/anie.202203970

Abstract

A 2-biphenylacetylene was fixed into a specific conformation within the confined cavity of a hollow cage, where it underwent a regioselective spirocyclization in the presence of an electrophile. A 5-endo-dig cyclization proceeded selectively in the cage, which stands in sharp contrast to the 6-endo-dig cyclization that normally occurs in common organic media. The folded conformation adopted by the substrate within the cage was examined by ¹ H NMR spectroscopy and X-ray crystallographic analysis.

Keywords: Dearomatization Reaction; Electrophilic Cyclization; Host-Guest Systems; Inclusion Compounds; Spiro Compounds.

Abstract

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