Synthesis 2006(10): 1590-1598  
DOI: 10.1055/s-2006-926458
PAPER
© Georg Thieme Verlag Stuttgart · New York

Syntheses of Ring-Fluorinated Isoquinolines and Quinolines via Intramolecular Substitution: Cyclization of 1,1-Difluoro-1-alkenes Bearing a Sulfonamide Moiety

Junji Ichikawa*a, Kotaro Sakodaa, Hiroko Moriyamab, Yukinori Wadaa
a Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Fax: +81(3)58414345; e-Mail: junji@chem.s.u-tokyo.ac.jp;
b Department of Applied Chemistry, Kyushu Institute of Technology, Sensui-cho, Tobata, Kitakyushu 804-8550, Japan
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Publikationsverlauf

Received 29 November 2005
Publikationsdatum:
27. April 2006 (online)

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Abstract

On treatment of a base such as NaH, KH, or Et3N, N-[o-(2,2-difluorovinyl)benzyl]- and N-[o-(3,3-difluoroallyl)phenyl]-substituted p-toluenesulfonamides readily undergo intramolecular substitution of sulfonamide nitrogens for vinylic fluorines in a 6-endo-trig fashion, leading to 3-fluoroisoquinoline and 2-fluoroquinoline derivatives, respectively, in high yields.

20

Anilide 7c (R = H) hardly gave dihydroquinoline 10c (R = H) on teatment with NaH, which suggests that 10c was formed via desilylation of 10b.

23

For the synthesis of 3-fluoroquinolines starting from (2,2-difluorovinyl)benzene substrates on the basis of the intramolecular substitution concept, see: Refs. 4e, 5b, 12b, and 12c.