- Sterics vs electronics: Revisiting the catalytic regioselective hydrodebromination of 2,3,5-tribromothiophene
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The application of sterically hindered palladium catalysts to the regioselective hydrodebromination of 2,3,5-tribromothiophene has been studied in detail, including the effects of catalyst choice, solvent, reaction time, and temperature, as well as the method of NaBH4 addition and the role of chelating additives to effect NaBH4 solubility. Ultimately it was determined that the background reaction between NaBH4 and bromothiophenes is too facile to allow both total conversion and high selectivity. Optimized conditions finally allowed a selectivity of ca. 16:1 with overall conversion of 100%. However, complications of overdebromination under these conditions still limit the yield of the desired 2,3-dibromothiophene to 65%.
- Konkol, Kristine L.,Rasmussen, Seth C.
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- Trapping of Transient Thienyllithiums Generated by Deprotonation of 2,3-or 2,5-Dibromothiophene in a Flow Microreactor
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Selective trapping of (4,5-dibromo-2-thienyl)lithium, known to undergo halogen dance, was achieved in a flow microreactor. This transient thienyllithium, generated by mixing 2,3-dibromothiophene and lithium diisopropylamide at-78 °C for 1.6 seconds, react
- Okano, Kentaro,Yamane, Yoshiki,Nagaki, Aiichiro,Mori, Atsunori
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supporting information
p. 1913 - 1918
(2020/11/10)
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- One-Pot Halogen Dance/Negishi Coupling of Dibromothiophenes for Regiocontrolled Synthesis of Multiply Arylated Thiophenes
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One-pot halogen dance/Negishi cross-coupling of readily available 2,5-dibromothiophenes is described. A lithium diisopropylamide (LDA)-mediated halogen dance reaction resulted in the formation of thermodynamically stable α-lithiodibromothiophenes, which w
- Okano, Kentaro,Sunahara, Kazuhiro,Yamane, Yoshiki,Hayashi, Yuki,Mori, Atsunori
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supporting information
p. 16450 - 16454
(2016/11/11)
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- Sterics versus electronics: Regioselective cross-coupling of polybrominated thiophenes
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Methods for the regioselective cross-coupling of 2,3,5-tribromothiophene have been developed in which selective aryl-aryl coupling occurs at the 5-position with yields up to 63%. The difference in reactivity of the α- and β-positions then allows sequential regioselective couplings first at the 2-position, followed by the 3-position. Such regioselective cross-coupling allows unprecedented control in the generation of trifunctionalized thiophenes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Amb, Chad M.,Rasmussen, Seth C.
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body text
p. 801 - 804
(2009/04/11)
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- Regioselective Debromination of 2,3,5-Tribromothiophene: A Facile Synthesis of Isomerically Pure 2,3- and 2,4-Dibromothiophene
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The regioselective preparative debromination of 2,3,5-tribromothiophene to isomerically pure 2,3- and 2,4-dibromothiophene was effected by the use of sodium borohydride in the presence and absence of transition metal catalyst using predetermined optimum conditions from GC trials.
- Xie, Yang,Ng, Siu-Choon,Hor, T. S. Andy,Chan, Hardy S. O.
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p. 150 - 151
(2007/10/03)
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