Dakin

Ethers of benzenepentol have been obtained by Dakin oxidation of the appropriately substituted acetophenone. Thus, the oxidation of 2-hydroxy-3,4,6-ttimethoxyacetophenone and 2-hydroxy-3,4,5-ttimethoxyacetophenone with hydrogen peroxide ia the presence of alkali gives l,2-dihydroxy-3,4,6-ttimethoxybenzene and l,2-dihydroxy-3,4,5-ttimethoxybenzene, respectively further methylation of these ethers yields the pentamethyl ether of benzenepentol (mp 58—59 degC) (253). The one-step aromatization of myoinositol to produce esters of pentahydroxybenzene is achieved by treatment with carboxylic acid anhydrides ia DMSO and ia the presence of pyridine (254) (see Vitamins). 6-Alkyl- or... 

J. Dakin and B. Culshaw, Optical Fiber Sensors, Vol. I, Principles and Components, Artech House, London, 1988. 

DAKIN WEST Acylation An acylative decartxixylation of o-amino acids or o-thio acids. 

The procedure described is similar to that of Dakin for the preparation of catechol. The reaction has been carried out using four times the quantities specified here the yield was 81% (C. F. H. Allen, private communication)... 

Dakin, R., Radial Inflow Turbines for Geothermal Application, Geothermal Resources Council, February 1986. 

A special application of heteroaromatic acylation via a modified Dakin-West reaction leads to a-fluoro ketone derivatives [50] (equation 30) Such fluoro ketones have been successfully used as enzyme inhibitors in modern bioorganic chemistry [5, 6]... 

Cohen and Dakin, Trans. Chem. Soc. 1S99, 76, 894 Cross and Cohen, Proc. Chem. Soc., 1908. 

In conclusion I desire to thank Dr. J. McCrae, who has written the section on Ethyl Tartrate and the use of the Polari-meter. Dr. T. S. Patterson, who has been kind enough to look over the proofs, and Mr. H. D. Dakin, who has given me substantial assistance in the practical work of revision. 

The Dakin reaction proceeds by a mechanism analogous to that of the Baeyer-Villiger reaction. An aromatic aldehyde or ketone that is activated by a hydroxy group in the ortho or para position, e.g. salicylic aldehyde 12 (2-hydroxybenzaldehyde), reacts with hydroperoxides or alkaline hydrogen peroxide. Upon hydrolysis of the rearrangement product 13 a dihydroxybenzene, e.g. catechol 14, is obtained ... 

When an a-amino acid is treated with an anhydride in the presence of pyridine, the carboxyl group is replaced by an acyl group and the NH2 becomes acylated. This is called the Dakin-West reaction The mechanism involves formation of an oxazolone. The reaction sometimes takes place on carboxylic acids even when an amino group is not present. A number of N-substituted amino acids, RCH-(NHR )COOH, give the corresponding N-alkylated products. 

In another kind of reaction, an aromatic aldehyde ArCHO or ketone ArCOR is converted to a phenol ArOH on treatment with alkaline H202, but there must be an OH or NH2 group in the ortho or para position. This is called the Dakin reac-The mechanism may be similar to that of the Baeyer-Villiger reaction (18-19) ... 

Reaction between amino acids and anhydrides (Dakin-West)... 

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