Calcium-Promoted Pictet-Spengler Reactions of Ketones and Aldehydes
作者:Matthew J. Vanden Eynden、Kamala Kunchithapatham、James P. Stambuli
DOI:10.1021/jo1019283
日期:2010.12.17
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.
Catalytic Pictet–Spengler reactions using Yb(OTf)3
作者:Kei Manabe、Daisuke Nobutou、Shū Kobayashi
DOI:10.1016/j.bmc.2005.05.018
日期:2005.9
The catalytic Pictet-Spengler reactions proceeded in high yields with high regioselectivity in the presence of a catalytic amount of Yb(OTf)(3) and a dehydrating agent at room temperature. High regioselectivities were obtained in these reactions, and it is suggested that the reactions proceeded under kinetic control. (c) 2005 Elsevier Ltd. All rights reserved.