Zwitterions and unobserved intermediates in organocatalytic Diels-Alder reactions of linear and cross-conjugated trienamines

Arne Dieckmann; Martin Breugst; K N Houk

doi:10.1021/ja312043g

Zwitterions and unobserved intermediates in organocatalytic Diels-Alder reactions of linear and cross-conjugated trienamines

J Am Chem Soc. 2013 Feb 27;135(8):3237-42. doi: 10.1021/ja312043g. Epub 2013 Feb 11.

Authors

Arne Dieckmann¹, Martin Breugst, K N Houk

Affiliation

¹ Department of Chemistry and Biochemistry, University of California-Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA.

PMID: 23350816
DOI: 10.1021/ja312043g

Abstract

The Diels-Alder reactions of cyclic linear and cross-conjugated trienamines with oxindoles have been studied with density functional theory [M06-2X/def2-TZVPP/IEFPCM//B97D/6-31+G(d,p)/IEFPCM]. These reactions are found to proceed in a stepwise fashion. Computations revealed that these transformations involve complex mechanisms including zwitterionic intermediates and several unstable alternate cycloadducts arising from (2 + 2) cycloadditions and hetero-Diels-Alder reactions. The observed regio- and stereochemistry can be rationalized by a combination of kinetic and thermodynamic control.