Categories: Synthesis of S-Heterocycles >
Synthesis of thiophenes and benzothiophenes
Name Reactions
Paal-Knorr Thiophene Synthesis
Recent Literature
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.
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.
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