Enantiocontrolled total synthesis of (+)-bakkenolide-A
作者:Andrew E. Greene、Fernando Coelho、Jean-Pierre Deprés、Timothy J. Brocksom
DOI:10.1016/s0040-4039(00)80838-2
日期:1988.1
An efficient, stereoselective totalsynthesis of natural bakkenolide-A has been effected from (S)-1,6-dimethyl-1-cyclohexene, which can be obtained from 2-methyl-2-cyclohexen-1-one in 3 high-yield steps.
asymmetric cyclization–carbonylation of propargyl ketols catalyzed by palladium(II) with chiral bisoxazoline (box) ligands. The 2S,3S enantiomer of (±)-6 was preferentially converted to 13 (45–49% yields, 37–46% ee), and the 2R,3R enantiomer of (±)-6 was preferentially converted to 14 (21–23% yields, 92–97% ee). As an application of this reaction, formal synthesis of (+)-bakkenolide A was achieved.
Applications of [2,3]-sigmatropic rearrangements to natural products synthesis. The total synthesis of .+-.-bakkenolide-A (fukinanolide)
作者:David A. Evans、Charles L. Sims、Glenn C. Andrews
DOI:10.1021/ja00458a037
日期:1977.8
A stereoselective total synthesis of the /3-methylene-y-lactone sesquiterpene, bakkenolide-A, is reported. The use of [2,3]-sigmatropic rearrangements within the context of constructing asymmetric quaternary centers has been explored. It has been found that steric factors appear to play a significant role in defining the levels of stereoselectivity observed in this class of molecular rearrangements
Fukinone (I), a new sesquiterpene ketone, was isolated from Petasites japonicus Maxim. Its structure and absoluteconfiguration were established by the interconversion from isopetasol (V), a sesquiterpene of known absoluteconfiguration, to dihydrofukinone (II).
A total synthesis of (+)-bakkenolide-A was carried out via the key intermediate 4, which was prepared based on an asymmetric cyclization-carbonylation reaction established in our laboratory. Diastereoselective construction of the spirolactone moiety was achieved using Mitsuhashi's protocol as a key step.