Hypervalent iodine oxidation of some 2,4-dihydroxyacetophenones with iodobenzene diacetate potassium hydroxide in methanol : A novel route to 2-hydroxy-3-iodo-4-phenoxyacetophenones
“…A preliminary account of this study was reported earlier (13). This observation, coupled with the fact that the rearranged products from this reaction i.e., o-iodo ethers, are potential precursors for the synthesis of a variety of interesting compounds such as dibenzofurans, which are associated with diverse physiological activities (14), prompted us to study the scope of this novel route.…”
α-Substituted 2,4-dihydroxyacetophenones (1a-1i) have been oxidized with phenyliodonium diacetate (PIDA) under three conditions (i) PIDA-KOH-MeOH (basic) at 0°C, (ii) PIDA-MeOH (neutral) at reflux temperature, and (iii) PIDA-AcOH (acidic) at reflux temperature, to afford novel o-iodophenoxy ethers (4a-4i) via rearrangement of respective iodonium ylides (5a-5i).
“…A preliminary account of this study was reported earlier (13). This observation, coupled with the fact that the rearranged products from this reaction i.e., o-iodo ethers, are potential precursors for the synthesis of a variety of interesting compounds such as dibenzofurans, which are associated with diverse physiological activities (14), prompted us to study the scope of this novel route.…”
α-Substituted 2,4-dihydroxyacetophenones (1a-1i) have been oxidized with phenyliodonium diacetate (PIDA) under three conditions (i) PIDA-KOH-MeOH (basic) at 0°C, (ii) PIDA-MeOH (neutral) at reflux temperature, and (iii) PIDA-AcOH (acidic) at reflux temperature, to afford novel o-iodophenoxy ethers (4a-4i) via rearrangement of respective iodonium ylides (5a-5i).
“…The desired spirocycle 31 was probably formed but it apparently reacted with some intact PIFA to give rise to the iodonium species 32, which then suffered a final phenyl shift to furnish 33. [43][44][45] It thus seemed, after all, that the methyl ether bond in 25a had its utility to select the reaction path leading to the desired spirocyclic system. When absent like in 25b, the resulting enol function of 31 is free to play other quick games with the PIFA reagent, such as the one delivering first 32, then 33.…”
This account reviews our investigations over the last ten years on the selective dearomatization of phenols into cyclohexadienones and its application in natural products synthesis. 7Understanding Dimerization: Cieplak or Not Cieplak? 7.1Total Synthesis of (+)-Aquaticol 7.2Toward an All-Embracing Rationale! 8Conclusions and Perspectives
“…efficient for hydroxylation of enolizable ketones via the initially formed R-hydroxydimethylacetal (eq 11). 15,[85][86][87][88] The synthetic potential of this reaction (eq 11) was thoroughly discussed in previous reviews. 15,19 Hydroxylation of some substituted acetophenones under these conditions is especially useful for the synthesis of various oxygen-containing heterocyclic compounds.…”
Section: Oxidations With Iodosylarenesmentioning
confidence: 99%
“…Even more useful and convenient are oxidations with the commercially available (diacetoxyiodo)benzene in basic methanolic solution, where the same reactive ingredient, PhI(OMe) 2 , is generated in situ. The reagent system PhI(OAc) 2 /KOH/MeOH is especially efficient for hydroxylation of enolizable ketones via the initially formed α-hydroxydimethylacetal (eq 11). ,− …”
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