Synthesis 2005(12): 1977-1990  
DOI: 10.1055/s-2005-869970
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Chiral ansa-Bridged Macrocyclic Lactams ([16]Metacyclophanes) Related to Geldanamycin

Aude Lemarchand, Thorsten Bach*
Lehrstuhl für Organische Chemie I, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
Fax: +49(89)28913315; e-Mail: thorsten.bach@ch.tum.de;
Further Information

Publication History

Received 28 February 2005
Publication Date:
24 June 2005 (online)

Abstract

Two chiral ansa-bridged lactams ([16]metacyclophanes) 2a,b were synthesized starting from 2-methoxyhydroquinone diisopropyl ether (6) in 14 (2a, 3.9% overall) and 16 synthetic steps (2b, 0.6% overall). Both compounds contain typical features of geldanamycin (1) in the C-1 to C-9 part of the ansa chain, i.e. the α,β,γ,δ-unsaturated anilide (C-1 to C-5), the carbamate at the stereogenic carbon atom C-7 and the E-double bond between C-8 and C-9. While the rest of the ansa chain (C-10 to C-15) was an alkyl chain in compound 2a, a more polar CH2OCH2CH2OCH2 chain was installed in compound 2b. Key step of the sequence was a ring-closing metathesis in which the ansa compounds 3 were formed as a mixture of isomers. Deprotection and oxidation to the quinone failed for diisopropyl ether 2b but was successfully conducted with precursor 2a.

1

Current address: Roche Diagnostics GmbH, Pharma Research Penzberg, Nonnenwald 2, 82372 Penzberg, Germany.