α-Acylamino radical cyclizations using allenes and vinylsilanes as addends: applications to the synthesis of (+)-heliotridine and (-)-dihydroxyheliotridine
作者:Jeffrey M. Dener、David J. Hart
DOI:10.1016/s0040-4020(01)86072-5
日期:1988.1
Total syntheses of the pyrrolizidine bases (+)-heliotridine (4) and (-)-dihydroxyheliotridane (5) from (S)-3-acetoxysuccinimide are described. The syntheses of 4 and 5 revolve around free radical cyclizations involving the use of allenes and vinylsilanes, respectively, as addends.
The synthesis of novel pyrrolo[3,2-c]isoquinolines is investigated starting from 3-aminosuccinimides. Various known routes leading to 3-aminosuccinimides were tested but a new approach via nucleophilic addition of arylalkylamines on maleimide gave better results. The regioselectivity of the reduction of these compounds was shown to depend on the degree of substitution of the concerned 3-aminosuccinimide
Stereoselective synthesis of pyrrolizidine alkaloids, (+)-heliotridine and (+)-retronecine, by means of an intermolecular carbenoid displacement reaction
作者:Tetsuji Kametani、Hirotaka Yukawa、Toshio Honda
DOI:10.1039/c39880000685
日期:——
The stereoselectivesynthesis of the pyrrolizidinealkaloids (+)-heliotridine and (+)-retronecine from (S)-malic acid has been achieved by employing an intermolecularcarbenoiddisplacementreaction as a key step.
A versatile approach to enantiopure (4S, 5R)-5-alkyl-4-hydroxy-2-pyrrolidinones is described. The key steps involve a regioselective Grignard reagent addition to (S)-malimides, and diastereoselective reductive dehydroxylation of the resulting hemi-azaketals. The flexibility of this methodology has been demonstrated by the synthesis of (2R, 3R)-3-amino-1-benzyl-2-methylpyrrolidine, the parent diamine
Synthesis of erythro-L-.BETA.-Hydroxyglutamic Acid Hydrochloride from L-Malic Acid.
作者:Sojiro SHIOKAWA、Tomihisa OHTA、Shigeo NOZOE
DOI:10.1248/cpb.40.1398
日期:——
Facile synthesis of erythro-L-β-hydroxyglutamic acid and its derivative, (2S, 3S)-3-acetoxypyroglutamate, from L-malimide is described. The Key reaction for the synthesis of 3-oxypyroglutamyl intermediate was the furylation of N-acylaminal acetate using zinc bromide-trimethylchlorosilane as an effective catalyst system. Oxidative cleavage of the furyl substituent afforded the 3-acetoxypyroglutamate, which on hydrolysis gave the title amino acid.