H.-P. Husson

Asymmetric synthesis: XII:Stereocontrolled electrophilic-nucleophilic α,α'-substitution of the pyrrolidine ring

Abstract The synthesis of 2-cyano-5-oxazolopyrrolidine 3 , a chiral pyrrolidine synthon, is described. Conditions were established that permitted sequential chemoselective reactions at the C-2 aminonitrile (electrophilic substitution) and at the C-5 aminoether (nucleophilic substitution) centres of 3 . A stereospecific decyanation of the alkylated aminonitrile allowed the formation of the first asymmetric centre at C-2 of the pyrrolidine ring. The first enantioselective synthesis of (+)-(S)-trans-2-heptyl-5-ethyl-pyrrolidine 9 , a component of the venom of the ant Solenopsis punctaticeps served as an example of the method. Both enantiomers of cis-2-heptyl-5-ethyl pyrrolidine 13 were obtained from the minor diastereomers 7 and 8 which were formed on reaction of oxazolidines 5a and 5b with Grignard reagents. The stereochemical outcome of the substitution reactions is discussed. In addition, full data on the synthesis of ant venon alkaloid (+)- (S)-trans-2-heptyl-5-butyl-pyrrolidine and its cis stereomer are given.

Nouveaux alcaloides indoliques derives de l'aristoteline extraits d'aristotelia australasica

Abstract The structure of seven new indole alkaloids 2 , 3 , 5 , 6 , 8 , 9 and 11 derived from aristoteline 1 have been determined from 1H NMR, 13C NMR, mass spectrometry data and chemical properties. The biogenesis of these alkaloids is discussed.

Alcaloides du Peripterygia marginata (baill.) loes. (célastracées)—II : Synthèses totales dans la série de la (±) périphylline

Resume Les syntheses totales univoques de deux squelettes isomeres comprenant un cycle a 8 elements A ou un cycle a 13 elements B ont permis de determiner la structure de la periphylline, alcaloide derive de la spermidine.

Aristolasol and aristolasene: Indole alkaloids from Aristotelia australasica

Abstract Aristolasol and aristolasene, two Aristotelia alkaloids, contain a new skeleton. Their structures were established by 1 H and 13 C NMR and mass spectrometric data.