13999-11-6Relevant articles and documents
Copper-/Silver-Mediated Arylation of C(sp2)-H Bonds with 2-Thiophenecarboxylic Acids
Zhao, Sheng,Liu, Yue-Jin,Yan, Sheng-Yi,Chen, Fa-Jie,Zhang, Zhuo-Zhuo,Shi, Bing-Feng
supporting information, p. 3338 - 3341 (2015/07/08)
A copper/silver-mediated arylation of (hetero)aryl C-H bonds with 2-thiophenecarboxylic acids has been achieved. The protocol features a broad substrate scope and high functional group tolerance. Preliminary mechanistic studies indicate that a cascade pro
Generation of 3- and 5-lithiothiophene-2-carboxylates via metal-halogen exchange and their addition reactions to chalcogenoxanthones
Cannon II, Michael K.,Detty, Michael R.
, p. 2647 - 2650 (2007/10/03)
Deprotonation and lithium-bromine exchange in 5- or 3-bromothiophene-2- carboxylic acids with t-BuLi form the corresponding dianion, which reacts highly regioselectively in the presence of 0.25 equiv of tetramethyl-1,2- ethylenediamine with 3,6-bis(dimethylamino) chalcogenoxanthones to give S- and Se-containing rhodamines. Quenching studies with D2O indicate that an extra equivalent of t-BuLi is not necessary in these reactions. Deprotonation is faster than metal-halogen exchange with the bromothiophene-2-carboxylic acids using t-BuLi.
HIGH-YIELD SYNTHESES OF 2,3-DISUBSTITUTED FURANS AND THIOPHENES
Carpenter, Andrew J.,Chadwick, Derek J
, p. 1777 - 1780 (2007/10/02)
The course of lithiation of furan- and thiophene-2-carboxylic acids is critically dependent on the identity of the lithium base allowing high-yielding syntheses of 2,3- and 2,5-disubstituted thiophenenes: the proposed use of a trimethylsilyl blocking group to control metallation in the furan acid provides a useful route to 2,3-disubstituted furans.
Regioselective α-and β-Metallations of Thiophene Derivatives Bearing the 4,4-Dimethyloxazolin-2-yl Group. Application of the Method to Syntheses of 2,3- and 2,5-Disubstituted Thiophene Derivatives
Carpenter, Andrew J.,Chadwick, Derek J.
, p. 173 - 182 (2007/10/02)
The effects of change of solvent, metallating agent, reaction time and temperature, and of the presence or absence of agents capable of complex formation with either the lithium cation or the oxazoline moiety, on the lithiation of 4,4-dimethyl-2-(2-thienyl)oxazoline are explored.Conditions are thereby established for high-yielding syntheses of the 3- and 5-lithio-intermediates and for control of regioselectivity of metallation.The nucleophilicity of 3-lithio-intermediate is profoundly solvent dependent, and appropriate conditions for reaction of both 3- and 5-lithiated species with a wide variety of electrophiles are presented.Syntheses of a range of 2,3- and 2,5-disubstituted thiophene derivatives have thereby been achieved, utilising, in addition, a new method for the transformation of oxazolino into carboxy functionality.The balance between basicity and nucleophilicity of the 3-lithio-intermediate in its reaction with - and -acetone is shown to be sensitive to isotope effects.
