Synthesis 2002(2): 0242-0252
DOI: 10.1055/s-2002-19804
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Optically Active C-Allylglycine Derivatives and Conversion into Isoquinolones

Nong Zhang, Udo Nubbemeyer*
Institut für Chemie - Organische Chemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
Fax: +49(30)83855163; e-Mail: udonubb@chemie.fu-berlin.de;
Further Information

Publication History

Received 16 July 2001
Publication Date:
03 August 2004 (online)

Abstract

C-Allylglycyl amides can be efficiently synthesized via an auxiliary controlled diastereoselective aza-Claisen rearrangement. The stereodirecting unit is placed on an auxiliary derived from commercially available (S)-proline. After N-allylation, the obtained optically active allylamines were reacted with various N-protected glycyl fluorides to give the (2R)-C-allylglycyl amides in good yields. The diastereoselectivity of the asymmetric allylation varied between 1:1 and >1:15 depending on the N-protective group, the auxiliary, and the reaction temperature. Likewise, the C-allyl-glycine derivatives can be used as monomers in peptide synthesis to synthesize (R)-proline derivatives or chiral isoquinolones; the latter should serve as building blocks in the total syntheses of alkaloids.

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For detailed data, see Figure [2] .

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Chiral HPLC analyses were run using triacetyl cellulose (Merck), Chirobiotic-V and Chirobiotic-T columns (Baker). Flow rates: 1-2 mL/min, eluents: MeOH, EtOH, i-PrOH and varying mixtures of alcohol-hexanes. For chiral 1H NMR shift experiments Eu(tfc)3 (tris-[3-(trifluoromethylhydroxy-methylene)-(+)-camphorato]europium) was used. Ana-lyzing the singlet at δ = 7.35, different downfield shifts were found for the enantiomers.