Bismuth triflate, addition with

I2 vapor is extremely corrosive while scandium compounds are moisture-sensitive and very expensive. In addition, these reactions are carried out in an environmentally unfriendly solvent, CH2CI2. We have reported the bismuth triflate-catalyzed synthesis of substituted dihydro-2//-1-benzopyrans by the condensation of substituted salicylaldehydes with 2,2-dimethoxypropane (Scheme 3) [22]. 

Diketones condense to furans or pyrroles in the presence of a primary amine and an acidic catalyst. Yadav has carried out numerous such reactions in the ionic liquid [BM1M][BF4], using bismuth triflate as a catalyst [256]. The reaction typically gave 80-90% yield and the ionic hquid/catalyst was easily recycled (Scheme 5.2-112). With the addition of a primary amine to a 1,4-diketone, pyrroles can be formed. 

To a solution of arene (1 1.0 mmol) and bismuth triflate (33 mg, 0.05 mmol) in nitromethane (1 mL) was slowly added 1,3-diene (2 1.5 mmol) in nitromethane (1 mL) over 1 hour at room temperature using a syringe pump. After the addition, the solution was stirred for another 1 h. After complete consumption of the aromatic compound (GC monitoring), the reaction mixture was quenched with a saturated aqueous solution of sodium bicarbonate, extracted thrice with diethyl ether, washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (pentane/Et20 100/0 to 90/10) to afford the indane derivative 3. All the products were characterized by spectral methods. 

A recent report has shown that tricyclopropylbismuth can be utilized in the cross-coupling reaction with aryl halides and triflates [57]. Representative examples are shown in Scheme 38. Addition of a base activator and excess of the bismuth reagents are necessary to obtain the coupling products in good yields, although more than one cyclopropyl group was transferred when 0.5 equivalents of... 

Certain Lewis acids are known to induce an epoxide-aldehyde rearrangement <01TL8129>, and this chemistry has recently been combined in tandem with metal-mediated allylations. For example, epoxides react with tetraallyltin in the presence of bismuth(III) triflate to give homoallylic alcohols 116. The reaction involves an initial 1,2-shift to form an aldehyde 115, which is then attacked by the allyl tin species <03TL6501>. A similar but operationally more straightforward protocol is available by combining allyl bromide with indium metal, followed by the addition of epoxide <03TL2911>. 

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