Direct Enantioselective Brønsted Acid Catalyzed N-Acyliminium Cyclization Cascades of Tryptamines and Ketoacids
摘要:
A direct enantio- and diastereoselective N-acyliminium cyclization cascade through chiral phosphoric acid catalyzed condensation of tryptamines with gamma- and delta-ketoacid derivatives to provide architecturally complex heterocycles has been developed. The reaction is technically simple to perform, atom-efficient, and broad in scope. Employing 10 mol % of (R)-BINOL derived chiral phosphoric acids in refluxing toluene allowed the polycyclic product materials to be generated in good yields (53-99%) and moderate to high enantioselectivities (68-98% ee).
Asymmetric synthesis of α-alkylated α-amino acids: azocane-2-carboxylic acids
作者:Gunda U. Georg、Xiangming Guan
DOI:10.1016/s0040-4039(00)77662-3
日期:1992.1
Alpha-Alkylated azocane-2-carboxylic acid methyl esters 5 were synthesized with excellent enantiomeric excess (> 96%) in four steps starting from optically active beta-keto esters 1. The synthesis involved tetrazole formation, reduction, protection, and oxidation.
XIE, ZHUO-FENG;SUEMUNE, HIROSHI;SAKAI, KIYOSHI, SYNTH. COMMUN., 19,(1989) N-6, C. 987-992