Mechanistic Duality in Tertiary Amine Additions to Thermally Generated Hexadehydro-Diels–Alder Benzynes
作者:Sean P. Ross、Beeraiah Baire、Thomas R. Hoye
DOI:10.1021/acs.orglett.7b02888
日期:2017.10.20
hexadehydro-Diels–Alder (HDDA)-generated benzynes. Tertiary amines are presumed to engage benzynes by generation of a zwitterionic intermediate. Simple trialkylamines undergo intermolecular protonation by a protic nucleophile to give an aryl ammonium intermediate that is then dealkylated. Amines containing acidified β-protons undergo an intramolecular elimination to give the aniline and an alkene. Finally, amino
The lipase-mediated kinetic resolution of racemic scopoline [(±)-4] and 6-hydroxytropinone [(±)-7] is reported. Whereas (±)-4 is difficult to resolve due to steric hindrance of the hydroxy function, the resolution of (±)-7 with vinyl acetate as acyl donor gave alcohol (+)-7 and the corresponding acetate (-)-9 with high enantiomeric excess. In case of the optimal result of 99% ee for (+)-7 and 80% ee for (-)-9, an E-value of 35 was calculated. The preparative lipase-catalyzed resolution of (±)-7 resulted in almost enantiopure alcohol (+)-7 with >99% ee after one recrystallization.
?Odorosid E?, Odorosid H, Odorosid-K-acetat und ?Kristallisat J?. Die Glykoside von Nerium odorumSol. 4. Mitteilung. Glykoside und Aglykone, 107. Mitteilung
作者:W. Rittel、A. Hunger、T. Reichstein
DOI:10.1002/hlca.19530360213
日期:——
Die Isolierung von Odorosid H, „Odorosid-E-acetat”, Odorosid-K-acetat, „Kristallisat J”, Scopoletin und Scopolin-tetracetat aus der Rinde von Neriumodorum wird beschrieben.