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2005
Enantioselective syntheses
O 0031
Development of Highly Stereoselective Asymmetric 6π-Azaelectrocyclization of
Flexible Linear 1-Azatrienes. From Determination of Multi01- 035 Conformationally
functional Chiral Amines, 7-Alkyl cis-1-Amino-2-indanols, to Application as a
New Synthetic Strategy: Formal Synthesis of 20-Epiuleine. — cis-1-Amino-2-indanols are found to be suitable substrates for the formation of chiral piperidines. Their
coupling with the enals (II) leads to 1-azatrienes which spontaneously undergo electrocyclization to fused piperidines. In some cases, high stereoselectivity is achieved. Subsequent treatment with LiAlH4 and MnO2-mediated oxidation offers a new, general, and
easy approach to chiral piperidine derivatives. The presence of a cis-hydroxy group in
aminoindanes is essential to achieve highly stereoselective electrocyclization. It also
facilitates oxidative removal of the indane auxiliary. This method can be applied successfully to the synthesis of the 20-epiuleine precursor (XII). — (TANAKA, K.;
KOBAYASHI, T.; MORI, H.; KATSUMURA*, S.; J. Org. Chem. 69 (2004) 18,
5906-5925; Sch. Sci. Technol., Kwansei Gakuin Univ., Sanda, Hyogo 669, Japan;
Eng.) — Jannicke
2005
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