- Switchable [3+2] and [4+2] Heteroannulation of Primary Propargylamines with Isonitriles to Imidazoles and 1,6-Dihydropyrimidines: Catalyst Loading Enabled Reaction Divergence
-
Isonitrile 1 due to its carbene-like reactivity serves generally as a one-carbon synthon in a diverse set of organic transformations. We report in this article that the isocyano group can also act as a polarized triple bond to undergo, as a two-atom synthon, heteroannulation with primary propargylamines 15. In addition, we serendipitously discovered that the reaction pathways can be modulated by simply changing the catalyst loading. In the presence of 0.1?equiv of Yb(OTf)3or TfOH, the reaction between 1 and 15 afforded exclusively imidazoles 16 by a formal [3+2] cycloaddition. At a higher catalyst loading (Yb(OTf)3(0.4?equiv) or TfOH (0.5?equiv)) under otherwise identical conditions, the same reaction furnished 1,6-dihydropyrimidines 17 in good to excellent yields by way of a formal [4+2] cycloaddition process. Mechanistic investigations indicated that both annulations went through an amidine intermediate resulting from the insertion of the isocyano group to the NH bond of the primary amine. Subsequent catalyst-loading-dependent 5-exo-dig or 6-endo-dig cyclization provided selectively the two heterocycles, respectively.
- Tong, Shuo,Wang, Qian,Wang, Mei-Xiang,Zhu, Jieping
-
-
Read Online
- TiCl4-mediated amination of propargylic esters
-
The TiCl4-mediated substitution of propargylic esters with amides afforded the corresponding α-substituted propargylic amides.
- Mahrwald,Quint
-
-
Read Online
- Silver-Catalyzed Synthesis of Substituted Pyridine Derivatives from N-Propargylic α-Enamino Esters
-
A wide range of substituted pyridine derivatives were synthesized in moderate to good yields from N-propargylic α-enamino esters. The synthetic strategy involved regioselective addition of a propargylamine to the α-carbon atom of an alkynyl ester to produce the N-propargylic α-enamino ester, which acted as the key intermediate in the synthesis.
- Sakthivel, Shanmugam,Sharma, Ashish,Balamurugan, Rengarajan
-
supporting information
p. 3941 - 3946
(2017/07/28)
-
- Novel method of tetramic acid synthesis: Silver-catalyzed carbon dioxide incorporation into propargylic amine and intramolecular rearrangement
-
Tetramic acid derivatives have been studied as biologically active heterocycle structures for pharmaceutical or agricultural chemicals. Conventional preparative approaches often require highly functionalized starting materials and harsh heating conditions in basic media. The present report provides a conceptually new synthetic strategy for the synthesis of tetramic acid derivatives from easily available propargylic amines and carbon dioxide with a silver salt and DBU under mild reaction conditions.
- Ishida, Tomonobu,Kobayashi, Ryo,Yamada, Tohru
-
supporting information
p. 2430 - 2433
(2014/05/20)
-
- An efficient and facile one-pot synthesis of propargylamines by three-component coupling of aldehydes, amines, and alkynes via C-H activation catalyzed by NiCl2
-
NiCl2 was found to be a highly efficient and effective catalyst for the one-pot three-component (A3) coupling of aldehydes, amines, and alkynes to produce propargylamines in nearly quantitative yields. Structurally divergent aldehydes, amines, and alkynes were converted into the corresponding propargylamines. No co-catalyst or activator is needed and water is the only byproduct of this novel protocol.
- Samai, Subhasis,Nandi, Ganesh Chandra,Singh
-
experimental part
p. 5555 - 5558
(2010/10/21)
-
- Regio- And stereoselective synthesis of fluoroalkenes by Directed Au(I) catalysis
-
Au-catalyzed hydrofluorlnation reactions of a range of functionalized alkynes are reported. In the presence of an appropriate directing group, localized with particular spacing from the pendant alkyne, regloselectlve and predictable conversion of the alky
- Gorske, Benjamin C.,Mbofana, Curren T.,Miller, Scott J.
-
supporting information; experimental part
p. 4318 - 4321
(2009/12/26)
-
- Rhodium-Catalysed Reactions of Propargylamines with CO/H2. Formation of Pyrroles and Butenolides
-
Rhodium-catalysed reactions of (arylpropargyl)amines with CO/H2 give β-arylpyrroles in good yields.Reactions of (alkylpropargyl)amines gave alkylpyrroles together with butenolides which are formed in an unusual reaction that probably involves double carbonylation, reduction of one carbonyl function and removal of the amine function by hydrogenolysis.The single-crystal X-ray structure of 5-methyl-N,3-diphenylpyrrole-2-carboxamide is recorded.
- Campi, Eva M.,Fallon, Gary D.,Jackson, W. Roy,Nilsson, Ylva
-
p. 1167 - 1178
(2007/10/02)
-