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Synthesis 2002(6): 0695-0713
DOI: 10.1055/s-2002-25759
REVIEW
© Georg Thieme Verlag Stuttgart · New York

5-Endo-Trig Radical Cyclizations

Hiroyuki Ishibashi*a, Tatsunori Satob, Masazumi Ikedab
a Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi, Kanazawa 920-0934, Japan
b Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8414, Japan
Fax: +81(76)2344476; e-Mail: isibasi@mail.p.kanazawa-u.ac.jp;
Further Information

Publication History

Received 30 January 2002
Publication Date:
26 April 2002 (online)

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Abstract

5-Endo-trig ring-closure is recognized as a disfavored process. However, a number of examples of such a type of cyclization have recently been reported. This review focuses on studies of 5-endo-trig radical cyclizations that provide new syntheses of five-membered carbo- and heterocyclic compounds.

  • 1 Introduction

  • 2 Reactions onto C=C Bonds

  • 2.1 4-Pentenyl Radicals

  • 2.2 Carbamoylmethyl Radicals

  • 2.2.1 Bu3SnH-Mediated Reductive Cyclizations of α-Halo Amides

  • 2.2.2 Ni/HOAc-Mediated Reductive Cyclizations of α-Halo Amides

  • 2.2.3 Cu(I)-Mediated Reductive Cyclizations of α-Halo Amides

  • 2.2.4 Mn(III)-Mediated Oxidative Cyclizations

  • 2.3 α-Amidoyl Radicals

  • 2.4 Vinyl Radicals

  • 2.5 Acyl Radicals

  • 2.6 Silicon-Centered Radicals

  • 2.7 Sulfur-Centered Radicals

  • 3 Reactions onto Oxygen Atoms of C=O Bonds

  • 4 Reactions onto Nitrogen Atoms of C=N Bonds

  • 5 Miscellaneous

  • 6 Conclusions

Key words

alkaloids - tributyltin hydride - cyclizations - 5-endo-trig - α-halo amides - manganese(III) acetate - radicals