Large-Scale Synthesis of the Anti-Cancer Marine Natural Product (+)-Discodermolide. Part 4: Preparation of Fragment C7-24
Citations Over TimeTop 10% of 2003 papers
Abstract
Coupling of C9-14 (4) and C15-21 (5a) fragments to produce the cis-trisubstituted olefin was achieved using Suzuki-type coupling conditions employed by Marshall (5a/tert-BuLi/B-OMe-9-BBN added to 4/Cs2CO3/Pd(dppf)2). The terminal (Z)-diene moiety was attached to aldehyde 10 by using a sequential Nozaki−Hiyama allylation and Peterson olefination sequence; careful monitoring of the disappearance of both diastereomeric β-hydroxysilanes was found to be essential for achieving a high yield. In the oxidation of alcohols 12 and 16 to 13 and 7, respectively, using iodobenzene diacetate and TEMPO, addition of a trace of water was found to be crucial for complete conversion. The C8-9 (Z)-olefin functionality was introduced on to aldehyde 13 using a Still−Gennari HWE reaction. Subsequent carbamate installation at C-19 followed by a reduction/oxidation sequence gave the title fragment C7-24 (7) ready to be coupled with the C1-6 fragment, which is described in Part 2 of this series.
Related Papers
- → Pyridyl Directed Catalyst-Free trans-Hydroboration of Internal Alkynes(2016)63 cited
- → Diastereomeric Resolution of rac-1,1′-Bi-2-naphthol Boronic Acid with a Chiral Boron Ligand and Its Application to Simultaneous Synthesis of (R)- and (S)-3,3′-Disubstituted 1,1′-Bi-2-naphthol Derivatives(2013)15 cited
- → Hydroboration–Suzuki cross coupling of unsaturated amino acids; the synthesis of pyrimine derivatives(2002)26 cited
- → Iodobenzene Dichloride(2003)1 cited
- The Synthesis of Iodobenzene Diacetate and [Hydroxy(tosyloxy)iodo] benzene.(2003)