Diastereoselective Total Synthesis of (±)-Schindilactone A, Part 1: Construction of the ABC and FGH Ring Systems and Initial Attempts to Construct the CDEF Ring System

• Published in: Chemistry, an Asian journal Vol. 7; no. 10; pp. 2321 - 2333
• Main Authors: Sun, Tian-Wen, Ren, Wei-Wu, Xiao, Qing, Tang, Ye-Feng, Zhang, Yan-Dong, Li, Yong, Meng, Fan-Ke, Liu, Yi-Fan, Zhao, Ming-Zhe, Xu, Ling-Min, Chen, Jia-Hua, Yang, Zhen
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.10.2012; WILEY‐VCH Verlag
• Subjects: Crystallography, X-Ray; Cycloaddition Reaction; fused-ring systems; Molecular Conformation; natural products; schindilactone A; Stereoisomerism; synthetic methods; total synthesis; Triterpenes - chemical synthesis; Triterpenes - chemistry
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201200363

First‐generation synthetic strategies for the diastereoselective total synthesis of schindilactone A (1) are presented and methods for the synthesis of the ABC, FGH, and CDEF moieties are explored. We have established a method for the synthesis of the ABC moiety, which included both a Diels–Alder reaction and a ring‐closing metathesis as the key steps. We have also developed a method for the synthesis of the FGH moiety, which involved the use of a Pauson–Khand reaction and a carbonylative annulation reaction as the key steps. Furthermore, we have achieved the construction of the central 7–8 bicyclic ring system by using a [3,3]‐rearrangement as the key step. However, unfortunately, when this rearrangement reaction was applied to the construction of the more advanced CDEF moiety, the anticipated annulation reaction did not occur and the development of an alternative synthetic strategy would be required for the construction of this central core. One for the money: The synthesis of the ABC, FGH, and CD ring systems of schindilactone A were explored. The synthesis of the ABC moiety involved a Diels–Alder reaction and a ring‐closing metathesis as the key steps, whilst that of the FGH moiety employed a Pauson–Khand reaction and carbonylative annulation reaction as the key steps. Construction of the central 7–8‐fused bicyclic ring involved a [3,3]‐rearrangement as the key step.