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Synlett 1994; 1994(7): 495-498
DOI: 10.1055/s-1994-22902
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Stereocontrol in [4+2]Type Cycloaddition of an Aldimine Derived from (S)-Ethyl Lactate with 2-Siloxy-1,3-butadienes

Kaori Ishimaru* , Kazutaka Watanabe, Yohsuke Yamamoto, Kin-ya Akiba
  • *Department of Chemistry, Faculty of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 724, Japan
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Publikationsdatum:
18. September 2002 (online)

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[4+2]Type cycloaddition of a chiral aldimine (1) derived from (S)-ethyl lactate with 2-siloxy-1,3-butadiene 2a was performed to give 4-piperidones 3a and 3b in high yields after treatment with TBAF. Relative stereochemistry at 2- and 6-positions was trans for both isomers. Chelation-controlled product 3b was obtained selectively by use of TiCl4-i-PrCN at -30°C and 3a was provided using TMSOTf or Zn(OTf)2 at 4 °C with high selectivity.