Takeda K,
Shimono Y,
Yoshii E.
*
Toyama Medical and Pharmaceutical University, Japan
A Short-Step Entry to (±)-Quadrone.
J. Am. Chem. Soc. 1983;
105: 563-568
DOI:
10.1021/ja00341a042
Key words
(±)-quadrone - sesquiterpene - [2+2] cycloaddition - Wagner–Meerwein rearrangement
- Kucherov reaction - aldol condensation - Jones oxidation
Significance
The sesquiterpene (±)-quadrone was isolated from Aspergillus terreus in 1978 and exhibits antitumor properties. Structurally, the natural product contains
a quadracyclic fused ring system around a central quarternary carbon atom. In 1983,
Yoshii and co-workers presented a formal synthesis, featuring a Wagner–Meerwein rearrangement.
Comment
Cyclobutane C was accessed through photochemical [2+2] cycloaddition and transformed into alcohol
G in three steps. Wagner–Meerwein rearrangement and subsequent oxidation yielded alkyne
H. Kucherov reaction to diketone I enabled aldol condensation to enone J. Deprotection followed by Jones oxidation gave access to carboxylic acid K, which was previously transformed to the natural product by Danishefsky and co-workers
in three steps.
