Electrochemical Synthesis of Dimerizing and Nondimerizing Orthoquinone Monoketals
Anodic oxidation of appropriately substituted 2-methoxyphenols or α-(2-methoxyphenoxy)-2-methylpropionic acids in the presence of methanol furnishes stable orthoquinone monoketals, and thus constitutes a valuable alternative to the use of chemical oxidants that are often based on toxic metallic spec...
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Veröffentlicht in: | Journal of organic chemistry 2004-12, Vol.69 (25), p.8731-8738 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Anodic oxidation of appropriately substituted 2-methoxyphenols or α-(2-methoxyphenoxy)-2-methylpropionic acids in the presence of methanol furnishes stable orthoquinone monoketals, and thus constitutes a valuable alternative to the use of chemical oxidants that are often based on toxic metallic species. The propionic acid derivatives are initially converted into O-spirolactonic quinone bisketals that are then selectively hydrolyzed into the desired monoketal compounds. In the absence of blocking substituents, orthoquinone monoketals spontaneously undergo Diels−Alder dimerizations into tricyclododecadienedienones with extraordinary site selectivity, regioselectivity, and stereoselectivity. Suggestions are made to open up a new track for a long awaited rationalization of these controls on the basis of the intramolecular [2 + 2] reactivity of these orthoquinone monoketal-derived cyclodimers. |
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ISSN: | 0022-3263 1520-6904 |
DOI: | 10.1021/jo048677i |