Evaluation of Amino Substituants as Nucleofugal Controllers of Regioselectivity and as Chelate Modulators of Stereoselectivity in Squarate Ester Cascades

Leo A. Paquette, Lung Huang Kuo, Jinsung Tae

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21 Citations (Scopus)


The tandem addition of an alkenyllithium reagent and a 2-lithioallylamine to squarate esters has been systematically examined. The effect of the sequencing of this twofold addition has been investigated. The extent to which the amino group is eliminated was found to be dependent on the structural features of the companion nucleophile. Also assessed was the comparative ease with which the amino and methoxy groups experience competitive β-elimination from the highly reactive, medium-ring dianionic intermediates. Attempts were made to curtail the level of competing 1,4-addition, and success was achieved by increasing the effective size of the O-alkyl groups in the squarate ester. The highly stereocontrolled transformations described represent a notably direct means for producing highly fused polycyclic compounds. Mechanistic considerations surrounding these reactions, which are characterized by an impressive enhancement of molecular scaffolding, are discussed.

Original languageEnglish
Pages (from-to)2010-2021
Number of pages12
JournalJournal of Organic Chemistry
Issue number6
Publication statusPublished - 1998 Mar 20


All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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