title: Design of an organocatalyst for the enantioselective Diels-Alder reaction with alpha-acyloxyacroleins.
abstract: We have realized the first enantioselective organocatalytic Diels-Alder reaction between alpha-substituted acroleins, such as alpha-acyloxyacroleins, and not only cyclic but also acyclic dienes. alpha-Acyloxyacroleins are useful as synthetic equivalents of alpha-haloacroleins. The present catalyst could be prepared in situ from pentafluorobenzenesulfonic acid (2.5-3.0 equiv) and chiral triamine (1 equiv) derived from H-l-Phe-l-Leu-N(CH2CH2)2. The enantioselective Diels-Alder reaction of 5-(benzyloxymethyl)cyclopentadiene, cyclopentadiene, cyclohexadiene, 2,3-dimethylbutadiene, and isoprene with alpha-(p-methoxybenzoyloxy)acrolein catalyzed by the above chiral ammonium salt (2.5-20 mol %) at -20-22 degrees C gave the corresponding adducts with 83, 83, 91, 92, and 88% ee, respectively.
authors.affiliation: Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan. ishihara@cc.nagoya-u.ac.jp
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ishihara
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakano