- Palladium-catalysed C2 or C5 direct arylation of 3-substituted thiophenes with aryl bromides
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The Pd(OAc)2/dppb system was found to be an efficient catalyst for the direct arylation of 3-substituted thiophene derivatives. The regioselectivity of the arylation strongly depends on the thiophene substituent and also on the nature of the aryl bromide. When using 3-formyl, 3-cyano, 3-methyl, 3-hydroxymethyl or 3-bromothiophene, the 2-arylated thiophenes were obtained with 76-95% regioselectivity; whereas, the arylation of 3-formylthiophene diethylacetal or 3-acetylthiophene gave the 5-arylated thiophenes with 52-90% regioselectivity. The use of congested aryl bromides favours the arylation at C5. These reactions were performed using only 0.1 mol% of catalyst. Moreover, this procedure has been found to be tolerant to a variety of functional groups on the aryl bromide such as formyl, propionyl, benzoyl, nitrile, and nitro. Georg Thieme Verlag Stuttgart.
- Dong, Jia Jia,Roy, David,Roy, Reny Jacob,Ionita, Marina,Doucet, Henri
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experimental part
p. 3530 - 3546
(2011/12/04)
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- Palladium-catalyzed C2 or C5 direct arylation of 3-formylthiophene derivatives with aryl bromides
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The system Pd(OAc)2/dppb was found to be an efficient catalyst precursor for the direct arylation of 3-formylthiophene derivatives. When using 3-formylthiophene, the 2-arylated thiophenes were obtained with regioselectivities of 76-86%, whereas the arylation of 3-formylthiophene diethyl acetal gave the 5-arylated thiophenes with regioselectivities of 6488%. These reactions were performed by using only 0.1 mol% of the catalyst. Moreover, this procedure has been found, to be tolerant to a variety of functional groups on the aryl bromide such as formyl, propionyl, benzoyl, nitrile, or nitro.
- Dong, Jia Jia,Doucet, Henri
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experimental part
p. 611 - 615
(2010/03/26)
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