- Highly selective palladium-catalyzed cross-coupling of secondary alkylzinc reagents with heteroaryl halides
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The highly selective palladium-catalyzed Negishi coupling of secondary alkylzinc reagents with heteroaryl halides is described. The development of a series of biarylphosphine ligands has led to the identification of an improved catalyst for the coupling of electron-deficient heterocyclic substrates. Preparation and characterization of oxidative addition complex (L)(Ar)PdBr provided insight into the unique reactivity of catalysts based on CPhos-type ligands in facilitating challenging reductive elimination processes.
- Yang, Yang,Niedermann, Katrin,Han, Chong,Buchwald, Stephen L.
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p. 4638 - 4641
(2015/01/08)
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- SYNTHESIS OF 2-ALKYLPYRIMIDINES VIA 2-ALKYL-1,4,5,6-TETRAHYDROPYRIMIDINES
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The condensation of 1,3-diaminopropane with alkanoic acids gives 2-alkyl-1,4,5,6-tetrahydropyrimidines.Dehydrogenation of the tetrahydropyrimidine derivatives over a palladium catalyst produces the 2-alkylpyrimidines in high yields.
- Pews, Richard Garth
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p. 1867 - 1872
(2007/10/02)
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- On the Chichibabin Amination of Pyrimidine and N-Alkylpyrimidinium Salts Using Liquid Ammonia/Potassium Permanganate
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Treatment of the 2-R-pyrimidines (1, R = methyl, ethyl, i-propyl and t-butyl) with potassium amide/liquid ammonia/potassium permanganate leads to amination at C-4(6).The yields of the 4(6)-amino compounds 3 increase in the order 2-methyl (10percent), 2-ethyl (30percent), 2-i-propyl (45percent) and 2-t-butyl (60percent).Treatment of the 2-R-N-methylpyrimidinium salts (4, R = hydrogen, methyl) with liquid ammonia/potassium permanganate leads to a regiospecific imination at C-6, the corresponding 2-R-1,6-dihydro-6-imino-1-methylpyrimidines 6 being obtained in 80-85percent yield.It is proved by 15N-labelling that no ring opening is involved in these imination reactions.Treatment of the imino compounds with base leads to the corresponding 2-R-6-methylaminopyrimidines 8, involving, as proved by 15N-labelling, an ANRORC-mechanism. 2-t-Butyl-1-ethylpyrimidinium tetrafluoroborate (9b) when treated with liquid ammonia/potassium permanganate undergoes N-deethylation, 2-t-butylpyrimidine being exclusively formed.
- Buurman, Dick J.,Plas, Henk C. van der
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p. 1377 - 1380
(2007/10/02)
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- Process for the preparation of a 2-alkylpyrimidine
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The process according to the invention for the preparation of a 2-propyl- or 2-butylpyrimidine, in which the corresponding 2-alkyl-1,4,5,6-tetrahydropyrimidine is dehydrogenated in the gas phase with a palladium-containing catalyst and in which a 2-propyl- or 2-butylpyrimidine is recovered from the reaction mixture, is characterized in that the gas-phase reaction is carried out using a carbon monoxide-hydrogen reactant. As this is understood a mixture of carbon monoxide and hydrogen and/or a compound capable of at least partial decomposing into CO and H2 under the reaction conditions.
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