Dakin oxidation reaction

Although alkaline conditions are normally employed, for reasons of safety it is occasionally advantageous to operate under neutral conditions where, for example, oxidation of benzaldehydes to benzoic acids may be desired rather than the Dakin reaction.210 Conversely alkyl benzaldehydes, which under most conditions would be expected to yield the corresponding benzoic acids, have been reported to undergo the Dakin-type reaction yielding alkyl phenols in the presence of strong acids.220... 

Page 350, change to DAKIN WEST REACTION N,N-Dimethyl-4-pyridinaminc. Page 352, change to OXIDATION OF SULFIDES TO SULFOXIDES. 

M.E. Jung and co-workers have developed a synthesis of selectively protected L-Dopa derivatives from L-tyrosine via a Reimer-Tiemann reaction followed by the modified Dakin oxidation. The formyl group introduced by the Reimer-Tlemann reaction had to be converted to the corresponding phenol. After trying many sets of conditions, the Syper process was chosen, which uses arylselenium compounds as activators for the oxidation. Treatment of the aromatic aldehyde with 2.5 equivalents of 30% hydrogen peroxide in the presence of 4% diphenyl diselenide in dichloromethane for 18h gave the aryl formate in excellent yield. This ester was cleaved by treatment with methanolic ammonia for 1h to afford the desired phenol in good yield. 

The total synthesis of (-)-(R)-MEM-protected arthrographol was accomplished by G.L.D. Krupadanam et al." authors used sequential Viismeier reaction/Dakin oxidation to prepare a 1,2,4-trihydroxybenzene derivative. 

The references at the end of the book are listed in alphabetical order, and the named reaction for which the references are listed is typed in blue and with boldface (see Dakin oxidation). Important the references are listed in chronological order when they appear as superscript numbers in the text (e g., reference 10 is a more recent paper than reference 12, but it received a smaller reference number because it was cited in the text earlier). 

Dabco s. Triethylenediamine Dakin oxidation 30, 67 Darzens-Claisen reaction 31,800 DBU s. 1,8-Diazabicyclo[5.4.0]-undec-5-ene... 

It should be noted that there are several other means by which the key a-aminocarbonyl intermediates of the Gutknecht synthesis may be prepared besides by the reduction of a-oximino ketones. The oxidation of a-aminoalcohols, reduction of a-amino acids and their derivatives, hydrolysis of a-acetamido ketones formed from a-amino acids and acetic anhydride by the Dakin-West reaction, and the reduction of a-azido, a-diazo, and a-nitro ketones all lead to dihydropyrazines by way of a-amino ketones. The Gastaldi synthesis provides an alternate use of a-oximino ketones, to afford dicyano pyrazines. ... 

Dakin oxidation 13, 183 15, 279 Darzens-Glaisen reaction 12, 847 Darzens synthesis of unsatd. ketones 11, 902... 

From a broader perspective, protein oxidation can result in covalent modification at many sites other than just at cysteine thiols. The earliest reports on protein oxidation date from the first decade of the twentieth century, but it took many more years to characterize these reactions and their products (Dakin, 1906). 

Similar to the Dakin-West procedure previously mentioned, the Henry nitro-aldol condensation reaction is most widely used to synthesize trifluoromethyl ketones, although there are many examples of a,a-difluoroalkyl ketones synthesized by this method (Table 6)JU 12271 The method for a,a-difluoroalkyl and trifluoromethyl ketone synthesis is identical except for the final oxidation although fluoroalkyl and a,a-difluoroalkyl ketones are easily oxidized by the Sarett method (Cr03/pyridine),[12 the corresponding trifluoromethyl ketones can only be oxidized under basic conditions (0.3 M NaOH) with KMn04Jul Also, in some of the syntheses of a,a-difluoroalkyl ketones, the nitro alcohol intermediate was protected by si-lylation with /ert-butylchlorodimethylsilane. The silyl group was later removed by TosOH prior to oxidation. The full details of this method are given in Section 15.1.4.3.2. 

Alkaline hydrolysis of benzal acetone structures to the corresponding aldehyde (XIX) and acetone and subsequent oxidation of the aldehyde (XIX) to the corresponding benzoic acid (V) do not seem to represent an actual degradation stage since oxidizing the aldehyde (XIX) under our mild standard conditions yielded only traces of the corresponding benzoic acid (V). The aldehyde (XIX) was rapidly decomposed via Dakin reaction to formic acid and 3-methoxy-S-methyl-o-benzoquinone, which is immediately degraded to phenolic humic compounds. 

The Dakin Reaction allows the preparation of phenols from aryl aldehydes or aryl ketones via oxidation with hydrogen peroxide in the presence of base. The aryl formate or alkanoate formed as an intermediate is subsequently saponified to yield the substituted phenol product. 

Aldehydes which contain electron-releasing substituents in the ortho or para position give phenol products via a formate intermediate. This reaction is known as the Dakin reaction, the oxidation of salicylaldehyde being a classic example (Figure 3.42).215... 

NaH, dimethylformamide (DMF), CH3I], undergoes electrophilic nitration (89), Friedel-Crafts acylation (90), and alkylation (91) at the C-9 position. Although attempts to effeet a Baeyer-Villiger oxidation of ketone 90 were successful, the route was laborious since oxidation to amine oxide 92 preceded oxidation of the methyl ketone 90. However, a Dakin reaction of aldehyde 91 gave 9-hydroxy-6-methylellipticine (93) in excellent yield. It remains to be seen if this methodology can be extended to an N-unsubstituted ellipticine. 

Dihydroxybenzene may be prepared from 2-hydroxybenzaldehyde by the Dakin reaction, which involves oxidation in alkaline solution by hydrogen peroxide (Scheme 4.15). The reaction involves a 1,2-shift to an electron-deficient oxygen and is similar to the cumene process used to synthesize phenol (Section 4.2). 

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