Highly efficient Lewis acid-catalysed Pictet–Spengler reactions discovered by parallel screeningElectronic supplementary information (ESI) available: full experimental procedures. See http://www.rsc.org/suppdata/cc/b2/b212063a/
Asymmetric synthesis of indolo[2,3-a]quinolizidin-2-ones - congeners to yohimbine-type alkaloids
摘要:
Schiff bases derived from tryptophan methyl ester and tryptamine react with Danishefkys diene in the presence of ZnCl2 to give enaminones which are subsequently transformed into indolo[2,3-a]quinolizidin-2-ones by acid-catalyzed cyclization. These tetracyclic aminoketones serve as viable intermediates in the construction of complex alkaloids, e. g. reserpine and deserpidine, and analogues thereof.
Asymmetric synthesis of highly functionalized tetracyclic indole bases embodying the basic skeleton of yohimbine- and reserpine type alkaloids
作者:Ralf Lock、Herbert Waldmann
DOI:10.1016/0040-4039(96)00388-7
日期:1996.4
Schiffbasesderivedfrom tryptophan methyl ester react with differently substituted electron-rich siloxy dienes in the presence of achiral or chiral boric acid esters to give enaminones 5 and 6 with high diastereomer ratios (up to >98:2). These intermediates are converted into highly functionalized indoloquinolizines 14 and 15 by means of a new method which employs the transformation of vinylogous
Enantioselective Construction of Highly Functionalized Indoloquinolizines—congeners to Polycyclic Indole Alkaloids
作者:Ralf Lock、Herbert Waldmann
DOI:10.1002/chem.19970030122
日期:1997.1
AbstractIndolo[2,3‐a]quinolizines have been prepared in enantiomerically pure form by a very short and efficient synthetic sequence consisting of a) formation of imines of tryptophan esters, b) their enantioselective reaction with substituted silyloxydienes mediated by a chiral or an achiral boron Lewis acid, and c) subsequent ring closure initiated by conversion of the generated vinylogous amides into vinylogous imidoyl chlorides. With this strategy various substituents can be incorporated directly into the 1‐position of the heterocyclic framework of complex indole alkaloids by the choice of an appropriate silyloxydiene, so that subsequent derivatization of the alkaloid precursor at this position is rendered unnecessary.
AMORNRAKSA, KITTI;GRIGG, RONALD;GUNARATNE, H. Q. NIMAL;KEMP, JAMES;SRIDHA+, J. CHEM. SOC. PERKIN TRANS.,(1987) N 10, 2285-2296
作者:AMORNRAKSA, KITTI、GRIGG, RONALD、GUNARATNE, H. Q. NIMAL、KEMP, JAMES、SRIDHA+