Categories: Synthesis of S-Heterocycles >
Synthesis of thiophenes and benzothiophenes
Copper-catalyzed tandem S-alkenylation of potassium sulfide with 1,4-diiodo-1,3-dienes enables an efficient synthetic approach to variously substituted thiophenes.
W. You, X. Yan, Q. Liao, C. Xi, Org. Lett., 2010, 12, 3930-3933.
An efficient one-step method for the synthesis of highly substituted thiophenes from thiomorpholides and α-haloketones was developed. The mechanism is discussed.
F. Matloubi Moghaddam, H. Zali Bionee, Tetrahedron, 2004, 60, 6085-6089.
An efficient and highly versatile microwave-assisted Paal-Knorr condensation of various 1,4-diketones gave furans, pyrroles and thiophenes in good yields. In addition, transformations of the methoxycarbonyl moiety, such as Curtius rearrangement, hydrolysis to carboxylic acid, or the conversion into amine by reaction with a primary amine in the presence of Me3Al, are described.
G. Minetto, L. F. Raveglia, A. Sega, M. Taddei, Eur. J. Org. Chem., 2005, 5277-5288.
Thionation of amides, 1,4-diketones, N-(2-oxoalkyl)amides, and N,N'-acylhydrazines with the use of a fluorous Lawesson's reagent leads to thioamides, thiophenes, 1,3-thiazoles, and 1,3,4-thiadiazoles in high yields. The isolation of the final products is achieved in most cases by a simple filtration.
Z. Kaleta, B. T Makowski, T. Soos, R. Dembinski, Org. Lett., 2006, 8, 1625-1628.
4-dimethylaminopyridine (DMAP) promotes an efficient and experimentally rapid protocol for the synthesis of 2,3-dicarboalkoxy-4-aroyl/heteroaroyl/alkanoyl thiophenes in high yields via 1-2 (C-S) and 3-4 (C-C) bond connections in only 3-5 min in DCM at room temperature. This method allows a clean and general synthesis of previously inaccessible and synthetically demanding thiophenes.
G. C. Nandi, S. Samai, M. S. Singh, J. Org. Chem., 2011, 76, 8009-8014.
An efficient one-pot procedure allows the synthesis of various functionalized 2-aminothiophene scaffolds catalyzed by L-proline in high yields under mild conditions. Low catalyst loading, simple procedure, and high yields are the important attributes of this methodology.
T. Wang, X.-G. Huang, J. Liu, B. Li, J.-J. Wu, K.-X. Chen, W.-L. Zhu, X.-Y. Xu, B.-B. Zeng, Synlett, 2010, 1351-1354.
A palladium-catalyzed C-H arylation of electron-enriched heteroarenes with aryl bromides and aryl chlorides proceeds in the presence of LiO-t-Bu as a base. Differently substituted 2,5-diarylthiazole can be obtained with the same catalyst system by switching the solvent and the amount of base.
S. Tamba, Y. Okubo, S. Tanaka, D. Monguchi, A. Mori, J. Org. Chem., 2010, 75, 6998-7001.
In the presence of CuI and TMEDA, a thiolation annulation reaction of 2-bromo alkynylbenzenes with sodium sulfide delivers various 2-substituted benzo[b]thiophenes in good yields.
L.-L. Sun, C.-L. Deng, R.-Y. Tang, X.-G. Zhang, J. Org. Chem., 2011, 76, 7546-7550.
Thiourea can be used as a cheap and easy to handle dihydrosulfide surrogate in C-S bond formation/cross-coupling/cyclization domino reactions. Structurally important biarylthioether, benzo[b]thiophenes, and thieno[3,2-b]thiophene scaffolds are provided in high yield.
M. Kuhn, F. C. Falk, J. Paradies, Org. Lett., 2011, 13, 4100-4103.
A gold-catalyzed carbothiolation provided an atom-economic way of synthesizing sulfur-containing heterocycles such as 2,3-disubstituted benzothiophenes.
I. Nakamura, T. Sato, Y. Yamamoto, Angew. Chem. Int. Ed., 2006, 45, 4473-4475.
A simple and highly efficient protodecarboxylation of various heteroaromatic carboxylic acids is catalyzed by Ag2CO3 and AcOH in DMSO. This methodology enables also a selective monoprotodecarboxylation of several aromatic dicarboxylic acids.
P. Lu, C. Sanchez, J. Cornella, I. Larrosa, Org. Lett., 2009, 11, 5710-5713.
Conditions for the palladium-catalyzed direct arylation of a wide range of heterocycles with aryl bromides employ a stoichiometric ratio of both coupling partners, as well as a substoichiometric quantity of pivalic acid, which results in significantly faster reactions. An evaluation of the influence of the nature of the aryl halide has also been carried out.
B. Liégault, D. Lapointe, L. Caron, A. Vlassova, K. Fagnou, J. Org. Chem., 2009, 74, 1826-1834.
Thiophene was regioselectively deprotonated by treatment with Bu3MgLi in THF at room temperature. The lithium arylmagnesate formed was either trapped with electrophiles or cross-coupled in a ‘one-pot’ procedure with aryl halides under palladium catalysis.
O. Bayh, H. Awad, F. Mongin, C. Hoarau, F. Trécourt, G. Quéquiner, F. Marsais, F. Blanco, B. Abarca, R. Ballesteros, Tetrahedron, 2005, 61, 4779-4784.