A biomimetic type expedient approach to the tricyclic core of xyloketals. Application to a short, stereocontrolled synthesis of alboatrin and a remarkable epi to natural isomerisation
作者:Debayan Sarkar、Subrata Ghosh、Ramanathapuram V. Venkateswaran
DOI:10.1016/j.tetlet.2009.01.086
日期:2009.4
An expedientsynthesis of the linear tetrahydrofurano benzopyran ring system of xyloketals is described involving an ortho ester Claisen rearrangement and an intramolecular cationic cyclisation. This strategy was applied for a short, stereocontrolled and high yield synthesis of the phytotoxic metabolite alboatrin.
Hypophosphite mediated carbon–carbon bond formation: total synthesis of epialboatrin and structural revision of alboatrin
作者:Stephen R. Graham、John A. Murphy、Alan R. Kennedy
DOI:10.1039/a907032j
日期:——
1-Ethylpiperidine hypophosphite (1-EPHP) has been used in the key radical-cyclisation step in a 6-step synthesis of the phytotoxic metabolite alboatrin and its epimer from orcinol. The synthesis demonstrates that the stereochemistry of the structure initially proposed for alboatrin requires revision.
Biomimetic type approach to the tricyclic core of xyloketals. Application to a short, stereocontrolled synthesis of alboatrin and first synthesis of xyloketal G
作者:Debayan Sarkar、Ramanathapuram V. Venkateswaran
DOI:10.1016/j.tet.2011.04.084
日期:2011.6
benzopyran ring system of xyloketals is described. An orthoester Claisen rearrangement of a chromenol and an intra-molecular cationic cyclization are the key steps in the synthesis. A short, stereocontrolled and high yield synthesis of the phytotoxic metabolite alboatrin was achieved employing this strategy. A unique case of Lewis acid catalyzed isomerization of epi-alboatrin to alboatrin was observed.
Structure of Alboatrin, a novel phytotoxin isolated from Verticillium albo-atrum has been elucidated on the spectroscopic data and has been confirmed by the synthesis. A biogenesis for the unique phytotoxin is suggested.