Synlett 2018; 29(20): 2717-2721
DOI: 10.1055/s-0037-1611276
letter
© Georg Thieme Verlag Stuttgart · New York

Synthesis of 8-Oxabicyclo[3.2.1]octanes by TiCl4-Mediated Reactions of 3-Alkoxycyclobutanones and Allenylsilanes

Tatsuo Onnagawa
,
Mizuki Yamazaki
,
Tomoyuki Yoshimura
,
Jun-ichi Matsuo*
Division of Pharmaceutical Sciences, Graduate School of Medical Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan   eMail: jimatsuo@p.kanazawa-u.ac.jp
› Institutsangaben
This work was supported by JSPS KAKENHI Grant Number 15K07855 and Kanazawa University SAKIGAKE project.
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Publikationsverlauf

Received: 27. August 2018

Accepted after revision: 02. Oktober 2018

Publikationsdatum:
29. Oktober 2018 (online)


Abstract

1-Substituted allenylsilanes reacted with 3-alkoxycyclobutanones in the presence of TiCl4 to afford 8-oxabicyclo[3.2.1]octan-3-ones stereoselectively. Nucleophilic attack of allenylsilanes to a 1,4-zwitterionic intermediate formed from 3-alkoxycyclobutanones and TiCl4­ followed by 1,2-silyl migration, five-membered cyclization with an alkoxy group, and seven-membered cyclization of titanium enolate was proposed. Deuteration and one-pot Peterson olefination suggested that alkyl titanium species were formed after cyclization to 8-oxabi­cyclo[3.2.1]octane skeletons.

Supporting Information