Ring Transformation of Glycidic Amides with Ortho-Metalated Phenols to Enantiopure 3-Hydroxychromanones.
A novel access to hitherto unknown enantiopure 2-alkylchroman-4-ones 10 was found by a reaction of ortho-metalated O-MOM-protected phenols with Weinreb amides 8 of enantiopure cis- or trans-glycidic acids. Upon acidic hydrolysis, the resulting o-MOMO-benzoyloxiranes 9 undergo ring transformation to 2-alkylchroman-4-ones 10. 2-Alkylidenecoumaran-3-ones 11 were formed as alternative products, depending on the configuration of the starting oxirane ring and on the type of phenol used as starting material.
Woydowski
Karsten
K
Institut für Chemie, Humboldt-Universität Berlin, Hessische Strasse 1-2, D-10115 Berlin, Germany.
Ziemer
Burkhard
B
Liebscher
Jürgen
J