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2005
Indan derivatives
Q 1050
Direct Organocatalytic Asymmetric Heterodomino Reactions: The Knoevenagel/
Sequence for the Highly Diastereoselective Synthesis
01- 089 Diels—Alder/Epimerization
of Symmetrical and Nonsymmetrical Synthons of Benzoanellated Centropolyquinanes. — Treatment of the indandione (I) with aldehydes and enones in the presence of chiral amino acids or amines offers a simple and efficient method to prepare
symmetrical and nonsymmetrical spiranes like (IV), (VI), (VIII), and (X). Under appropriate conditions this Knoevenagel/Diels—Alder/epimerization sequence proceeds
with high diastereoselectivity but low enantioselectivity. The reaction with the dialdehyde (XI) gives the topologically interesting dispirane (XIII). In the presence of pyrrolidine the symmetrical spirane (XIV) is also formed via a Michael/retro Michael/
Diels—Alder/epimerization reaction sequence. These spiranes are potent precursors of
fenestranes. — (RAMACHARY, D. B.; ANEBOUSELVY, K.; CHOWDARI, N. S.;
BARBAS*, C. F. I.; J. Org. Chem. 69 (2004) 18, 5838-5849; Dep. Chem., Scripps
Res. Inst., San Diego, La Jolla, CA 92037, USA; Eng.) — Jannicke
2005
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