Bismuth mandelate

Oxidative cleavage of epoxide to carboxylic acids with bismuth mandelate general procedure... 

A solution of bismuth mandelate ((Bi(mand)2)20 392 mg, 0.4 mmol) in anhydrous DMSO (5 ml) was stirred at 80°C for 30 min under air. An appropriate epoxide (4 mmol) was added and the resulting mixture was stirred at 70-110°C for 22 h to 12 days. Acid hydrolysis, extraction of organic phase with ether, treatment of the organic extract with aqueous NaOH, acidification of the aqueous extract to pH 1-2, and re-extraction with ether followed by evaporation afforded the corresponding carboxylic acid [93TL2601]. 

Some bismuth(III) carboxylates catalyze the oxidative C-C bond cleavage of epoxides into carboxylic acids in a DMSO-O2 system (Scheme 14.109) [229], In the initial stage DMSO transfers an oxygen atom to epoxides activated by Bi(OCOR)3, producing a-hydroxy ketones [230]. a-Hydroxy ketones can be converted into carboxylic acids by O2 under bismufh(III) mandelate catalysis (Scheme 14.110). In the presence of catalytic amounts of Bi and Cu(OTf)2, 1,2-disubstituted epoxides are oxidized to a-diketones by a combination of O2 and DMSO (Scheme 14.111) [231]. The mechanism presumably involves two catalytic cycles fhe first oxidative ringopening to a-hydroxy ketones is catalyzed by Cu(OTf)2-DMSO, and the second oxidation to a-diketones is achieved by the Bi /Bi redox cycle under the action of O2. 

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