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Totalsynthese von (+)-2-epi-Deoxoprosopinin und neue Hydrazin-Harze für die organische Festphasensynthese

By Jan Hendrik Kirchhoff


This Ph. D. thesis deals with two different topics of organic synthesis, the total synthesis of (+)-2-epi-deoxoprosopinine and the development and application of novel haydrazine resins for solid phase synthesis. In the first part, the asymmetric synthesis of (+)-2-epi-deoxoprosopinine in twelve steps in 23% overall yield and with excellent diastereomeric and enantiomeric purity (de,ee >=96%) is described. As key steps the 1,2-addition of a dodecyl nucleophile to an aldehyde-SAMP hydrazone and the a -alkylation of 2,2-dimethyl-1,3-dioxan-5-one SAMP hydrazone were employed to generate two of the three stereogenic centers. Creation of the third stereogenic center was achieved in a domino deprotection/cyclisation/reduction sequence. In the second part, a novel N-butyl-N-methylpolystyrene-hydrazine linker resin was developed. Polymer supported hydrazones, readily prepared from aldehydes and the hydrazine resin, react with alkyl- and arylorganolithium reagents under 1,2-addition to the C-N double bond to afford the corresponding hydrazines. Release from solid support was achieved by reductive N-N bond cleavage to furnish a -branched primary amines, which were isolated as their corresponding amides in good overall yields and in high purity (12 examples). This methodology could be extended to the asymmetric synthesis of the a -branched amines by the employment of immobilized enantiopure b -methoxyamino auxiliaries. After transformation into their corresponding hydrazines, acylated a -branched primary amines were prepared according to the procedure described above in good overall yields and enantiomeric excesses of up to 86%

Topics: info:eu-repo/classification/ddc/540, Chemie, Desoxoprosopinin, Totalsynthese, Asymmetrische Synthese, Hydrazon-Methode, Organische Synthese, Festphasentechnik, Kunstharz, Ankergruppe
Publisher: Publikationsserver der RWTH Aachen University
Year: 2001
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Provided by: RWTH Publications
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