Iodobenzene-Catalyzed α-Acetoxylation of Ketones. In Situ Generation of Hypervalent (Diacyloxyiodo)benzenes Using m-Chloroperbenzoic Acid

Abstract

Reported here for the first time is the iodobenzene-catalyzed alpha-oxidation of ketones, in which diacyloxy(phenyl)-lambda3-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid serves as a terminal oxidant. Oxidation of a ketone with m-chloroperbenzoic acid in acetic acid in the presence of a catalytic amount of iodobenzene, BF3.Et2O, and water at room temperature under argon affords an alpha-acetoxy ketone in good yield. p-Methyl- and p-chloroiodobenzene also serve as efficient catalysts in this direct oxidation. We found that when the reaction was carried out in the absence of a catalytic amount of iodobenzene, Baeyer-Villiger oxidation of a ketone took place. It is noted that use of water and BF3.Et2O is crucial to the success of this alpha-acetoxylation.

Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone: Oxidation of p-Alkoxyphenols to p-Benzoquinones

“…Methyl and methoxy groups on the benzene ring showed [10][11][12]. These results show that the electron-donating alkoxy group at the para position on the benzene ring would increase the catalytic efficiency of iodoarene, in contrast to the reported results using m-CPBA 19,20) and H 2 O 2 30) as a co-oxidant. Slower reaction was observed using 0.1 eq of 4-iodoanisole (entry 13).…”

“…Moreover, pentavalent iodine reagents are potentially explosive. To overcome these disadvantages, catalytic hypervalent iodine oxidations [16][17][18] using mchloroperbenzoic acid (m-CPBA), [19][20][21][22][23][24][25][26][27] Oxone ® (2KHSO 5 · KHSO 4 · K 2 SO 4 ), 28,29) and H 2 O 2 30) as a co-oxidant have been reported recently.Development of efficient methods for synthesis of pquinone and p-quinone derivatives is an important subject in synthetic organic chemistry because they are structural components of numerous natural products and useful synthetic intermediates. [31][32][33][34][35][36] A convenient procedure for p-quinones was hypervalent iodine oxidation of p-alkoxyphenols using PIFA.…”

“…Moreover, pentavalent iodine reagents are potentially explosive. To overcome these disadvantages, catalytic hypervalent iodine oxidations [16][17][18] using mchloroperbenzoic acid (m-CPBA), [19][20][21][22][23][24][25][26][27] Oxone ® (2KHSO 5 · KHSO 4 · K 2 SO 4 ), 28,29) and H 2 O 2 30) as a co-oxidant have been reported recently.…”

Efficient Synthesis of p-Quinols Using Catalytic Hypervalent Iodine Oxidation of 4-Arylphenols with 4-Iodophenoxyacetic Acid and Oxone

“…30) Moreover, the solubility of 3 in alkaline solution makes its separation and recovery steps easier to carry out without a purification step. As part of our study for development of catalytic hypervalent iodine oxidations, [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] we report herein an efficient synthesis of p-quinols directly from 4-arylphenols using catalytic amount of 3 and Oxone ® in tetrahydrofuran (or 1,4-dioxane)-water (Chart 2). We first examined 4-phenylphenol (1a) as a model substrate ( Table 1).…”

Catalytic Hypervalent Iodine Oxidation of p-Dialkoxybenzenes to p-Quinones Using 4-Iodophenoxyacetic Acid and Oxone

“…To overcome these disadvantages of these reagents, catalytic hypervalent iodine oxidations were developed recently. [16][17][18][19][20][21][22][23][24][25][26][27][28] We also reported a catalytic hypervalent iodine oxidation of p-alkoxyphenols to p-quinones using a catalytic amount of 4-iodophenoxyacetic acid (1) with Oxone ® (2KHSO 5 · KHSO 4 · K 2 SO 4 ) as a novel system. 29) This system presents the following advantages.…”