Bisammonium salts of mono-N-alkylated chiral 1,2-diamino-1,2-diphenylethane (DPEN) were employed in the catalytic and asymmetric Diels-Alder reaction between cyclopentadiene and crotonaldehyde. The N-3-pentyl diamine·2HCl catalyst shows high endo/exo selectivity and endo-enantioselectivity for the cycloaddition, and this organocatalysis is the first example of the use of a chiral 1,2-diamine to generate an imine intermediate which is activated by an internal ammonium Brønsted acid for the cycloaddition in a wet solvent.
Bibliographical noteFunding Information:
This work was financially supported by the Center for Molecular Design and Synthesis (CMDS) at KAIST.
- Ammonium salts
- Asymmetric Diels-Alder
ASJC Scopus subject areas
- Drug Discovery
- Organic Chemistry