Total Synthesis of (−)-Rosmarinecine by Intramolecular Cycloaddition of (<i>S</i>)-Malic Acid Derived Pyrroline <i>N</i>-Oxide
作者:Andrea Goti、Martina Cacciarini、Francesca Cardona、Franca M. Cordero、Alberto Brandi
DOI:10.1021/ol015747o
日期:2001.5.1
[reaction in text] Straightforward total syntheses of (-)-rosmarinecine have been achieved from L-malic acid derived pyrroline N-oxides by two novel useful cascade processes, which join the family of domino reactions. Both strategies, which furnished the target alkaloid in enantioenriched and enantiopure forms, respectively, allow complete control of configuration at all the three newly created contiguous
Lipase-catalyzed domino kinetic resolution of α-hydroxynitrones/intramolecular 1,3-dipolar cycloaddition: a concise asymmetric total synthesis of (–)-rosmarinecine
作者:Shuji Akai、Kouichi Tanimoto、Yukiko Kanao、Sohei Omura、Yasuyuki Kita
DOI:10.1039/b419426h
日期:——
reactions were developed to directly provide tetrahydrofuro[3,4-c]isoxazole derivatives (5 and 9) in > or =90% ee from racemic alpha-hydroxynitrones (2 and 6), which were used in the concise asymmetrictotalsynthesis of (-)-rosmarinecine .
[structure: see text] Crambescidin 359 (4), which is the "vessel part" of the pentacyclic guanidine alkaloid ptilomycalin A (1), was synthesized for the first time based upon successive 1,3-dipolar cycloaddition reaction. This synthesis established the absolute stereochemistry of 4.
Synthesis of Enantiopure 3-Substituted Pyrroline <i>N</i>-Oxides by Highly Regioselective Oxidation of the Parent Hydroxylamines: A Mechanistic Rationale
The syntheses of four new, differently O-substituted 3-hydroxypyrroline N-oxides and the first 3-amino analogue have been performed by the use of a strategy involving double nucleophilicdisplacement of the corresponding dimesylates by hydroxylamine and oxidation of the resulting 1-hydroxypyrrolidines. The regioselectivity data of the oxidation reactions nicely confirm the mechanistic hypothesis, which
The protecting-group-freeasymmetrictotalsynthesis of (−)-rosmarinecine was achieved in only four steps from the commercially available (±)-3-hydroxypyrrolidine hydrochloride (2a). The key steps include the direct oxidation of (±)-2a to (±)-3-hydroxy-1-pyrroline N-oxide (1a) using the Davis reagent and the domino reaction; viz., the lipase-catalyzed dynamic kinetic resolution of (±)-1a with 1-ethoxyvinyl