Woodward glycolization

Woodward glycolization, 128 Woodward s chlorophyll synthesis, 258-259 Woodward s reagent K, 236 Woodward-Hoflmann rules examples, 262, 289 See also Electrocyclic reactions)... 

Wang, P., Woodward, C.A., and Kaufman, E.N., Polyethylene glycol)-modified ligninase enhances pentachlorophenol biodegradation in water-solvent mixtures, Biotechnol. Bioeng., 64, 290-297, 1999. 

In the Woodward procedure, water is present which intercepts the intermediate (c) to give a cishydroxy ester (e) and a cis-glycol on subsequent hydrolysis. 

Woodward cis-hydroxylation. The hydrox-ylation of an olefin with iodine and silver acetate in acetic acid to give cw-glycols. The method involves the trans addition of iodine and silver acetate to give a trans-iodo-acetoxy derivative. The latter is hydrolyzed to a cw-mono-glycol acetate with acetic acid and water. Alkaline hydrolysis results in the final cis-glycol. 

Woodward and Brutcher Jr.128 described the conversion of olefins into d,s-a>glycols by iodine and silver acetate in aqueous acetic acid. The reaction gives cis-fi-hydroxy -acetates in one operation, and thence hydrolysis affords the ds-flc-glycols. Applications in steroid chemistry129 and elsewhere have given the method general importance130-132 for ds-hydroxylation. 

When combined with I2, AgOAc in aqueous or anhydrous AcOH reacts with olefins to form vicinal diols (glycols). The hydroxylations are not always cis [Woodward Bratcher 7.4/w Chem Soc 80 209 1958, Ginsberg J Am Chem Soc 75 5746 1953, BaiMey et al. J Am Chem Soc 76 5014 1954, Klass et al. J Am Chem Soc 77 2329... 

Woodward [61] used a glycol acetonide to protect a double bond from reduction but never, in fact, regenerated the double bond instead the glycol was oxidatively cleaved at a later stage. Slates and Wendler [62, 63] su ested that glycols and their derivatives might be of use in protection of olefins and they developed a method of regenerating the double bond by treatment of the dimesylate with sodium iodide. The techniques... 

The combination of A -bromoacetamidc, silver acetate, and dry acetic acid has been shown to be superior to Woodward s procedure for the rfy-hydroxylation of olefins. Work up of the reaction mixture is simply effected by hydrolysis of the dioxolenium ion, followed by cleavage of the hydroxyacetate intermediate with lithium aluminium hydride. The use of a co-oxidant, such as sodium chlorate or hydrogen peroxide, allows the addition of catalytic quantities of osmium tetroxide to prepare c/y-diols from olefins. However the reaction is often complicated by further oxidation of the glycol to the a-ketol. The use of tertiary amine A -oxides, particularly A -methylmorpholine A -oxide, prevents this oxidation and gives higher yields of the desired product (Table 6). Another variation on this theme employs... 

On diene condensation with butadiene, the 4-methoxy-2,5-toluquinone (307) obtained from toluquinone in three stages with a yield of 26% formed the cis adduct (308), which on alkaline isomerization and reduction gave the trans-C/D glycol (309). Treatment of this with an aqueous dioxane solution of sulfuric acid led to hydrolysis and dehydration to a hydroxyketone forming an acetate (310). The treatment of compound (310) with metallic zinc in acetic anhydride enabled a CD fragment to be obtained, the so-called "Woodward s ketone" (311) this completed the formation of the bicyclic precursor. 

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