New strategies for natural products containing chroman spiroketals

Content Provider	Scilit
Author	Green, Jason C. Burnett, G. Leslie Pettus, Thomas R. R.
Copyright Year	2012
Abstract	Two cycloaddition strategies are described that lead to various chroman spiroketals from assorted exocyclic enol ethers. Unlike conventional thermodynamic ketalization strategies, the stereochemical outcome for this approach is determined by a kinetic cycloaddition reaction. Thus, the stereochemical outcome reflects the olefin geometry of the starting materials along with the orientation of the associated transition state. However, the initial kinetic product can also be equilibrated by acid catalysis and reconstituted into a thermodynamic stereochemical arrangement. Thus, these strategies uniquely enable synthetic access to either the thermodynamic or kinetic conformation of the spiroketal stereocenter itself. Applications of these strategies in the syntheses of berkelic acid, β-rubromycin, and paecilospirone are presented along with the use of a chroman spiroketal for the construction of heliespirones A and C.
Related Links	http://europepmc.org/articles/pmc4280069?pdf=render https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4280069/pdf https://www.degruyter.com/downloadpdf/journals/pac/84/7/article-p1621.pdf
Ending Page	1631
Page Count	11
Starting Page	1621
ISSN	00334545
e-ISSN	13653075
DOI	10.1351/pac-con-11-10-34
Journal	Pure and Applied Chemistry
Issue Number	7
Volume Number	84
Language	English
Publisher	Walter de Gruyter GmbH
Publisher Date	2012-05-02
Access Restriction	Open
Subject Keyword	Pure and Applied Chemistry Organic Chemistry Diels–alder [4 + 2] Cycloaddition Aromatic Aryl Spiroketals Chroman Natural Products Ortho-quinone Methide Oxidative [3 + 2] Cycloaddition Spiroketals Total Synthesis Journal: Pure and Applied Chemistry, Vol- 84
Content Type	Text
Resource Type	Article
Subject	Chemistry Chemical Engineering