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Synlett 2001; 2001(10): 1506-1510
DOI: 10.1055/s-2001-17475
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Synthesis of 1-Azaspirocycles via Lewis Acid-Mediated Spirocyclization of Cyclic N-Acyl-N,O-acetals

Toshimasa Ito* , Naoki Yamazaki, Chihiro Kibayashi
  • *School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan; Fax + 81-426-76-4475; E-mail: kibayashi@ps.toyaku.ac.jp
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Publication Date:
27 September 2001 (online)

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A new approach to 1-azaspirocycles has been developed starting from cyclic N-acyl-N,O-acetals. This sequence involves olefin-iminium cyclization mediated by Lewis acids leading to the spirocyclization products including the chlorinated products and the olefinic products. Mixtures of these products underwent catalytic hydrogenation and reductive dechlorination to produce the 1-azaspirans.

N-acyl-N,O-acetals - Lewis acid - iminium ions - spirocyclization - 1-azaspirocycles

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