Total Synthesis of (−)-Denticulatins A and B Using Efficient Methods of Acyclic Stereocontrol.
作者:Ian Paterson、Michael V. Perkins
DOI:10.1016/0040-4020(95)01015-7
日期:1996.1
The totalsynthesis of (−)-denticulatin B (2) was achieved in 9 steps (20% yield), with 70% overall diastereoselectivity, starting from the ethyl ketone (R)-9. Most of the stereochemistry was introduced by substratebased control. Key steps include the boron-mediated aldol/reduction, 9 → 22, the titanium-mediated aldol coupling, 26 + 8 → 38, and the directed cyclisation, 35 → 2. Epimerisation at C10
Condensation of pyridone 6 with enal 25 using DMAP in EtOH at 150 degreesC afforded 8% of the desired Diels-Alder adduct 22, 8% of the bridged adduct 36 and 1-2% of a partially pure cis-fused adduct 37 of unknown stereochemistry. Hydroxylation of 22 completed a short synthesis of fusaricide (1).