The first cyclopenta[b]benzofuran derivative, rocaglamide, from
During the past few years, indigenous to southeast Asia, the plant genus
An earlier attempt to synthesize rocaglamide
Synthesis of di-epi-rocaglamide.
Davey and Taylor [
Synthetic approach (a) of racemic (±)-rocaglamide.
Taylor et al. [
Synthetic approach (b) of racemic (±)-rocaglamide.
In 2001, Dobler et al. modified Taylor’s method [
Synthetic approach (c) racemic (±)-rocaglamide.
In 2008, Qin’s group synthesized (±)-rocaglamide and its 2,3-di-epi analogue by introducing the strategy of intramolecular reductive coupling to construct the cyclopenta[b]benzofuran skeleton [
Synthetic approach (d) racemic (±)-rocaglamide.
In 2009, Frontier group reported the total synthesis of aglafolin, rocagloic acid, and rocaglamide using Nazarov cyclization initiated by peracid oxidation (Scheme
Synthetic approach (e) racemic (±)-rocaglamide.
Trost et al. were successful in the enantioselective synthesis of (−)-rocaglamide (
Synthesis of (−)-rocaglamide.
In 2004, Gerard group introduced a biomimetic approach to the rocaglates employing photogeneration of oxidopyryliums derived from 3-hydroxyflavones (Scheme
Synthesis of (±)-methyl rocaglate.
Subsequently, Gerard group completed the asymmetric synthesis of the rocaglamides by enantioselective photocycloaddition mediated by chiral Brønsted acids [
Enantioselectivity synthesis of (−)-rocaglamide.
Bruce et al. synthesized the analogue of (±)-rocaglamide
Synthesis of analogue of (±)-rocaglamide
Stereoselective synthesis of the rocaglamide skeleton.
To summarize, in past years of effort, the synthetic methods of the rocaglamide have been developed rapidly, but valuable approaches are still few. At present, only intramolecular cyclization and biomimetic cycloaddition are effective and applied approaches for the synthesis of rocaglamide. It is very essential to perfect asymmetric Michael cycloaddition by the rigidity of molecular in intramolecular cyclization approach and to increase the synthetic total yield and region and stereoselectivity of the cycloaddition reaction in biomimetic cycloaddition approach. In the future, we believe more novel and effective approaches for the synthesis of rocaglamide will be developed.
The authors thank the National Natural Science Foundation of China (no. 20962006) and the Natural Science Foundation of the Guizhou Education Department (no. 20090021) for financial support.