We describe an asymmetric total synthesis of the pyrrolo[3,2-c]quinoline natural product martinellic acid starting from pyrroglutamic acid. A convergent strategy involving a Pd-catalyzed aryl amination reaction of a chiral, non-racemic pyrrolidine derivative incorporates the C2-chiral center which controls the remaining two stereocenters. Elaboration of this adduct through a Grieco-elimination sets the stage for a diastereoselective intramolecular [3+2] azomethine ylide-alkene cycloaddition and the construction of the remaining two chiral centers. Elaboration of the cycloadduct and incorporation the prenyl guanidine units delivered martinellic acid after removal of the protecting groups.
Starting frompyrrole, the novel 3,4-didehydropyrohomoglutamate 8 or (ent)-8 can be efficiently synthesized in up to 91% ee, which can be utilized as a versatile building block toward functionalized pyrrolidin-2-ones. Moreover, (ent)-8 can be readily converted to (S)-Vigabatrin, being an irreversible inhibitor for GABA-T, which is used as adjunctive therapy in patients that suffer from epilepsy.
Highly diastereoselective alkylation of chiral tin(II) enolates onto cyclic acyl imines. An efficient asymmetric synthesis of bicyclic alkaloids bearing a nitrogen atom ring juncture
作者:Yoshimitsu Nagao、Wei Min Dai、Masahito Ochiai、Shigeru Tsukagoshi、Eiichi Fujita
DOI:10.1021/jo00291a012
日期:1990.2
Synthesis of 2-Oxa and 2-Aza Analogs of Pyrrolizidine-3,5-diones (Lukes-Sorm Dilactam)
The synthesis of 2-oxa and 2-aza analogs of pyrrolizidine-3,5-dione (Lukes-Sorm dilactam), which has amnesia reversal activity, is reported. Optically active (+)-2-oxa and (+)-2-aza analogs [(+)-2 and (+)-3] and racemic 2-aza analog and its 1-methoxycarbonyl derivatives [(+)-3 and (+)-13 and -14] were prepared from (-)-S-pyroglutamic acid and succinimide, respectively.
Palladium-catalyzed aryl-amidation. Synthesis of non-racemic N-aryl lactams
The Buchwald/Hartwig aryl amination method was used to construct a series of chiral, non-racemic N-aryl pyrrolidinones from a common pyrrolidinone precursor and the corresponding aryl bromide. The stereochemical integrity of the N-aryl lactam after cross-coupling was proven by synthesis of the racemic compounds and comparison by H-1 NMR spectroscopy using Pirkle's chiral solvating agent. (C) 2003 Elsevier Ltd. All rights reserved.