3748-83-2Relevant academic research and scientific papers
Rhodium-catalyzed gram-scale synthesis of highly substituted pyridine derivatives
Parthasarathy, Kanniyappan,Cheng, Chien-Hong
experimental part, p. 1400 - 1402 (2010/01/16)
Rhodium-catalyzed chelation-assisted activation of the β-C-H bond of α,β-unsaturated ketoximes and subsequent reaction with alkynes affords highly substituted pyridine derivatives. This new method provides an opportunity for the one-pot synthesis of pyrid
Rhodium-catalyzed one-pot synthesis of substituted pyridine derivatives from α,β-unsaturated ketoximes and alkynes
Parthasarathy, Kanniyappan,Jeganmohan, Masilamani,Cheng, Chien-Hong
, p. 325 - 328 (2008/09/19)
(Chemical Equation Presented) A rhodium-catalyzed chelation-assisted C-H activation of α,β-unsaturated ketoximes and the reaction with alkynes to afford highly substituted pyridine derivatives is described.
(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - a Selective Catalyst for the Pyridine Synthesis
Nehl, Hans
, p. 2535 - 2538 (2007/10/02)
(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt (1) cactalyses the synthesis of various pyridines from alkynes and nitriles under mild conditions.Only small amounts of benzenes are formed in this selective reaction. - Key Words: Cobalt complexes, (η3-allyl)(η5-pentamethylcyclopentadienyl)- / Pyridine synthesis / Catalytic activity / Chemoselectivity
ACYLATION D'ALCENES DANS LE SYSTEME ACYLANT ACIDE TRIFLUOROMETHANESULFONIQUE-HALOGENURE D'ACIDE
Roussel, Christian,Rajoharison, Harivelo G.,Metzger, Jacques
, p. 613 - 618 (2007/10/03)
The diacylation of 2-methyl-2-pentene and of related alcoholic precursors with trifluoromethanesulphonic acid/acetyl chloride was investigated. The initially formed pyrylium salts were converted directly into the corresponding pyridines. The influence of the reaction conditions (temperature; molar ratios AcCl/F3CSO3H/alkene; experimental procedure) was thoroughly examined permitting the observation of new aspects for the examined synthesis of pyrylium salts e.g.: a) formation of less substituted pyrylium salts 2 up to 94 percent selectivity; b) direct access to isomeric pyrylium salts 1 and 2 depending on the reaction conditions; c) formation of triacylation products 3, 4 which could be suppressed in favour of 2. The described procedure presents also experimental advantages (no crackings; easily tractable reaction mixtures).
Process for preparing pyrylium salts
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, (2008/06/13)
A process for selectively preparing isomers of polysubstituted pyrylium salts from isoolefins or isoolefin precursors comprises diacylating the isoolefin or isoolefin precursor with a carboxylic acid anhydride in the presence of an acid having a Hammett acidity function, at about 22°-25° C. when pure, between -10 and -5. This method is selective to obtain the most substituted isomer of pyrylium salt that can be obtained from the isoolefin or isoolefin precursor.
Diacylation of alkenes catalyzed by sulfonic acids 3: application of weak sulfonic acids to the regioselective synthesis of pyrylium salts from isoolefins and linear olefins
Rajoharison, Harivelo G.,Roussel, Christian
, p. 307 - 313 (2007/10/02)
The use of weak sulfonic acids (methanesulfonic and α-carboxyalkanesulfonic acids) as catalysts in diacylation of disymmetrical isoalkenes by carboxylic acid anhydrides afford almost exclusively the more substituted pyrylium salt.Particularly, simple isoalkenes (generated in situ from dimethyl alkyl carbinols) and citronellol lead 2,3,4,6-tetrasubstituted pyrylium salts in high yields.Diacylation of 1-alkenes lead to 2,3,6-trialkyl-substituted pyrylium without isomerization but in low yield.The observed lower regioselectivities in comparative reactions catalyzed by strong protonic acids (perchloric acid or trifluoromethanesulfonic acid which are the classical catalysts in this kind of synthesis) confirm that the strenght of the catalyst governs the regioselectivity of the diacylation of olefins when carboxylic acid anhydrides are used as sources of acylating agents.In all cases, the obtained pyrylium salts were transformed into the corresponding pyridines by treatment with concentrated ammonia.
PREPARATION OF PYRIMIDINES AND PYRIDINES FROM ALKYL KETONES AND NITRILES IN PRESENCE OF PHOSPHORYL CHLORIDE
Zielinski, Wojciech
, p. 1639 - 1644 (2007/10/02)
The reaction of alkyl ketones with nitriles in the presence of POCl3 has been examined.It has been found that N-vinylimidoyl dichlorophosphates initially formed react further with excess nitriles or ketones to afford pyrimidine or pyridine derivatives, respectively.
