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Synlett 2010(8): 1197-1200  
DOI: 10.1055/s-0029-1219812
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Racemic, N-Benzylated Neoechinulin A and Isoneoechinulin A [¹]

Jernej Wagger, Uroš Grošelj, Jurij Svete, Branko Stanovnik*
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, PO Box 537, 1000 Ljubljana, Slovenia
Fax: +386(1)2419220; e-Mail: branko.stanovnik@fkkt.uni-lj.si;
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Publication History

Received 3 February 2010
Publication Date:
09 April 2010 (online)

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Abstract

Two N-benzylated analogues of the antioxidant, radical scavenging, and neuroprotective alkaloid neoechinulin A were prepared. Since, according to SAR studies, stereochemistry does not play an important role, both analogues were prepared in racemic form, using enaminone chemistry.

Key words

N-benzylated alkaloid analogues - neoechinulin A - diketopiperazines - enaminones - 2-isoprenylated - 2-prenylated indoles

1

The term isoneoechinulin A is proposed by authors of this work and refers to the prenyl group replacing the isoprenyl group in neoechinulin A. This nomenclature is used for naming compound 2.

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1

The term isoneoechinulin A is proposed by authors of this work and refers to the prenyl group replacing the isoprenyl group in neoechinulin A. This nomenclature is used for naming compound 2.

22

A crystal structure of isoprenylated analogue 1 was established from monocrystal, but the diffraction data were poor for the isoprenylated region of the molecule; although the X-ray structure obtained unambiguously showed a Z orientation around the exocyclic double bond.