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. 2013 Sep 20;15(18):4842-5.
doi: 10.1021/ol402254p. Epub 2013 Sep 3.

A highly stereoselective Diels-Alder cycloaddition of enones with chiral cyclic 2-amidodienes derived from allenamides

Li-Chao Fang  1 , Richard P Hsung, Zhi-Xiong Ma, William R Presser
Affiliations

A highly stereoselective Diels-Alder cycloaddition of enones with chiral cyclic 2-amidodienes derived from allenamides

Li-Chao Fang et al. Org Lett. .

Abstract

Lewis acid promoted Diels-Alder cycloadditions of a series of de novo chiral cyclic 2-amidodienes are described. These cyclic 2-amidodienes are derived from chiral α-allyl allenamides via a sequence of E-selective 1,3-H shift and 6π-electron pericyclic ring closure. With enones serving as effective dienophiles, these cycloadditions can be highly diastereoselective depending upon the chiral amide substituent, thereby representing a facile entry to optically enriched [2.2.2]bicyclic manifolds.

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Figures

Figure 1
Figure 1
X-Ray Structures of 22a, 27b, and 29a.
Figure 2
Figure 2
Different Facial Preference of Chiral Amides.
Scheme 1
Scheme 1
Cyclic 2-Amidodienes in [4 + 2] Cycloadditions.
Scheme 2
Scheme 2
Effect of the Chiral Auxiliary on Selectivity.
Scheme 3
Scheme 3
Assignment of Possible exo-Cycloadducts.
See this image and copyright information in PMC

References

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    1. Also see: Standen PE, Kimber MC. Curr Opin Drug Discov & Devel. 2010;13:645.Deagostino A, Prandi C, Tabasso S, Venturello P. Molecules. 2010;15:2667.

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