title: Calcium-promoted Pictet-Spengler reactions of ketones and aldehydes.
abstract: Calcium bis-1,1,1,3,3,3-hexafluoroisopropoxide is shown to be an effective catalyst for Pictet-Spengler reactions of 3-hydroxyphenethylamine and 3-hydroxy-4-methoxyphenethylamine with various aldehydes and ketones. Previous Lewis acid catalyzed Pictet-Spengler reactions of unactivated ketones typically require two separate reactions (imine formation, cyclization) to obtain the same results. The reactions described within directly provide 1,1'-disubstituted tetrahydroisoquinolines from the corresponding amine and ketone. These rare examples of Pictet-Spengler reactions of unactivated ketones demonstrate the unique nature of calcium as a Lewis acid catalyst.
authors.affiliation: Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Vanden Eynden
authors.forename: Kamala
authors.initials: K
authors.lastname: Kunchithapatham
authors.forename: James P
authors.initials: JP
authors.lastname: Stambuli