Abstract
Preliminary investigations of asymmetric Diels-Alder reactions using a new chiral
auxiliary are presented. The auxiliary is readily prepared from an aldehyde and asparagine
in water. The resulting heterocycle is coupled with acryloyl chloride in the same
pot to provide chiral dienophiles. These are reacted with cyclopentadiene at room
temperature in water or ethanol-water to provide cycloaddition adducts diastereoselectively,
as demonstrated by chiral HPLC of saponification products 5-norbornene-2-carboxylic
acids (47-64% ee for the endo isomers; endo/exo 82:18).
Key words
Diels-Alder reactions - asymmetric synthesis - diastereoselectivity - enantiomeric
resolution - green chemistry
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