Toward a Total Synthesis of Macrocyclic Jatrophane Diterpenes – Concise Route to a Highly Functionalized Cyclopentane Key Intermediate

✍ Scribed by Johann Mulzer; Gerald Giester; Michael Gilbert

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: German
• Weight: 354 KB
• Volume: 88
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200590124

✦ Synopsis

Abstract

A total synthesis of the biologically potent jatrophane diterpenes pepluanin A (1) and euphosalicin A (2) is being aimed at. En route to these targets, a concise synthesis of the nonracemic cyclopentane building block 74 was developed. Key steps were a Claisen–Eschenmoser rearrangement of the enantiomerically enriched allylic alcohol 14 to amide 34 (Scheme 7), a hydroxy‐lactonization of 40 to 43 (Scheme 9), followed by trans‐lactonization to 72, which was subjected to a Davis hydroxylation to 69 (Scheme 17). Eventually, compound 69 was converted into the enol triflate 74. This material should prove suitable for an annulation of the macrocyclic ring characteristic of the desired jatrophanes 1 and 2. Less‐successful approaches are also discussed due to their intrinsically valuable information content.