Gary W. Morrow

Mixed Quinone Monoketals via Iodobenzene Diacetate Oxidation

Abstract Oxidation of p-methoxyphenol, 4-methoxynaphthol and 4-acetamidophenol with iodobenzenediacetate in various alcohols as solvent afforded the corresponding mixed quinone or naphthoquinone monoketals in good yield. Oxidation of p-methoxyphenol in the presence of sorbyl alcohol led to in situ intramolecular Diels-Alder reactions proceeding by way of the corresponding mixed quinone monoketal.

Conjugate reduction of quinone derivatives. A route to phenol keto-tautomer equivalents

Abstract 1,4-addition of hydride to quinone monoketals 1 and p -quinol ethers 2, mediated by bis-(2,6-di- t -butyl-4-methylphenoxy)-methylaluminum (MAD), affords 4,4-substituted-2-cyclohexen-1-ones 3, which represent keto-tautomer equivalents of phenols.

Oxygenated phenanthrenes via quinol ketals: Cyclization vs. migration

Abstract 2-methoxyphenanthrenes were prepared by reaction of lithiated 2-bromostyrenes with quinone monoketals followed by acid-mediated cyclization of the resulting p-arylquinol kelals. Substitution at the bromostyrene side-chain or the quinone monoketal ring had only a modest effect on yields, but oxygen substitution on the bromostyrene aromatic nucleus resulted in a competing 1,2-aryl migration arising during the quinol ketal cyclization step. The extent of this rearrangement was found to be a function of the Lewis acid/solvent system employed.

Syntheses of Para-Terphenyl via Reductive Deoxygenation of Quinol Derivatives

Abstract Syntheses of para-terphenyl via reductive aromatization of 1,4-dioxygenated-1,4-diaryl-2,5-cyclohexadienes are described1

6-Endo Heck Cyclization of 3-(2-Iodophenoxy)methylbenzofurans: A Useful Approach to Pterocarpenes

Abstract Mitsunobu coupling of 3-hydroxymethylbenzofurans with o-iodophenols affords 3-(2-iodophenoxy)methylbenzofurans which under go a useful 6-endo Heck cyclization under Jeffery conditions to afford pterocarpene-type heterocycles. The unsubstituted parent pterocarpene thus prepared was readily converted to coumestan via subsequent PCC oxidation. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Synthesis of Pterocarpan-Type Heterocycles via Oxidative Cycloadditions of Phenols and Electron-Rich Arenes

Abstract Oxidation of 4-alkoxyphenols or 4-methoxynaphthol with phenyl iodonium(bis)trifluoroacetate (PIFA) in the presence of electron rich 2H-chromenes or dihydronaphthalenes affords pterocarpans or 5-carbapterocarpans via a formal [3 + 2] cycloaddition process. Acid-catalyzed ionization of quinone dimethylmonoacetal in the presence of 7-methoxy-2H-chromene gave similar results, suggesting a phenoxonium ion intermediate in the oxidative process.

OXYGENATED DIHYDROPHENANTHRENES VIA QUINOL ACETALS : A BRIEF SYNTHESIS OF ORCHINOL

Abstract The dihydrophenanthrene phytoalexin Orchinol was synthesized in 5 steps from commercially available 3,5-dimethoxybenzaldehyde. The approach utilized a new synthon, p-benzoquinone dibenzylmonoacetal, which served as a phenol 3,4-dication equivalent in an arylation-cyclization sequence.

A convergent approach to substituted phenanthrenes via quinol ketals

Abstract Reaction of 2′-lithiostyrenes with p -benzoquinone monoketals gives p quinol ketals which undergo Lewis acid-catalyzed cyclization and aromatization, affording 2-methoxyphenanthrenes.