Bismuth III salts

Oxidation of oleflns to tra/is-l,2-diol diacetates with bismuth acetate typical procedure for dry system 

Bismuth acetate (4.75 g, 12.3 mmol) was heated under reflux for 1 h in dry acetic acid (40 ml) containing acetic anhydride (ca. 17%). To the cooled solution, cyclohexene (3.01 g, 36.6 mmol) and iodine (9.39 g, 37.0 mmol) were added and the resulting mixture was further refluxed for 17.5 h. Usual work-up followed by distillation gave rrans-1,2-diacetoxycyclohexane (3.56 g, 80%) with no trace of the cw-isomer [89CC407]. 

The modified Prevost reaction uses bismuth acetate instead of silver benzoate. From a mechanistic point of view, iodine is considered to be the actual oxidant, and hence the bismuth acetate may work merely as the acetoxy source. Major advantages of this method over the previously reported analogous ones are as follows (i) bismuth-containing wastes are non-toxic, (ii) bismuth acetate is inexpensive, and (iii) less metal salt is needed, since three acetoxyl groups can be transferred per one bismuth atom. 

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]. 

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Bismuth(III) Salts as Synthetic Tools in Organic Transformations. 229... 

Mohammadpoor-Baltork I, Khosropour AR (2002) Efficient and selective conversion of trimethylsilyl and tetrahydropyranyl ethers to their corresponding acetates and benzoates catalyzed by bismuth(III) salts. Monatsh Chem 133 189-193... 

Initial investigations in the Mannich-type reaction of silyl enolates with benzal-dehyde and aniline employed a series of bismuth(III) salts (Scheme 9, Table 10). These results were promising because the corresponding (l-amino ketone could be obtained in moderate to good yield with bismuth halides, except bismuth fluoride (Table 10, entries 1 1). Bismuth nitrate smoothly afforded the expected product (Table 10, entry 5). While bismuth acetate gave no conversion, bismuth trifluor-oacetate provided the product in only moderate yield (Table 10, entries 6 and 7). Phenyl bismuth ditriflate and diphenyl bismuth triflate appeared to be more efficient catalysts than all those previously tested (Table 10, entries 8 and 9). Bismuth(III) triflate led to the expected product in a good yield and in a short reaction time, without any difference between the anhydrous and the hydrated form (Table 10, entries 10 and 11). 

Table 10 Mannich-type reaction of benzaldehyde, aniline, and (l-phenylvinyloxy)trimethylsilane using bismuth(III) salts as catalyst...

Bismuth(III) Salts for Sjvl-type Substitutions of Activated Alcohols. 118... 

New Applications for Bismuth(III) Salts in Organic Synthesis From Bulk Chemicals to Steroid and Terpene Chemistry... 

Abstract Bismuth(III) salts are currently considered efficient and ecofriendly reagents and catalysts for the development of new applications in organic synthesis. The preparation of bismuth(III) triflate and its analogues is reviewed as well as some of their applications to the synthesis of bulk chemicals via electrophilic addition and cyclization reactions. The use of bismuth(III) salts in the development of new chemical processes involving steroids and terpenes as substrates is also discussed. 

Keywords Bismuth triflate Bismuth(III) salts Corticosteroids Steroids... 

Scheme 31 Bismuth(III) salt-catalyzed rearrangement of 5P,6P-epoxycholestan-3P-yl acetate using MeN02 as solvent...

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