20147-50-6Relevant academic research and scientific papers
Catalytic Transformations of Alkynes into either α-Alkoxy or α-Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile-Directed Chemoselectivity
Sahani, Rajkumar Lalji,Patil, Manoj D.,Wagh, Sachin Bhausaheb,Liu, Rai-Shung
, p. 14878 - 14882 (2018/10/15)
The catalytic formation of gold enolates from alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile-directed chemoselectivity through cooperative catalysis. For 1-alkyn-4-ols and 2-ethynylphenols, their gold-catalyzed nitrone oxidations afforded N-containing dihydrofuran-3(2H)-ones with syn selectivity. The mechanism involves the Mannich reactions of gold enolates with imines through an O-H-N hydrogen-bonding motif. For aryloxyethynes, their gold enolates react selectively with nitrones to deliver 3-alkylidenebenzofuran-2-ones, as controlled by a C-H-O hydrogen-bonding motif.
Catalytic enantioselective inverse-electron demand 1,3-dipolar cycloaddition reactions of nitrones with alkenes
Simonsen,Bayon,Hazell,Gothelf,Jorgensen
, p. 3845 - 3853 (2007/10/03)
A general reaction protocol for catalytic enantioselective 1,3-dipolar cycloaddition reaction of nitrones, activated by chiral Lewis acids, with electron-rich alkenes has been developed. The nitrones are activated by various chiral 2,2'-dihydroxy-1,1'-binaphthyl (BINOL)-AlMe complexes, and it has been found that 3,3'-diaryl-BINOL-AlMe complexes catalyze a highly regio- , diastereo-, and enantioselective 1,3-dipolar cycloaddition reaction of aromatic nitrones with vinyl ethers, giving the exo-diastereomer of the isoxazolidines with de's up to > 90% and up to 97% ee. The reaction has been investigated under various conditions with different nitrones and vinyl ethers (and alkenes), and a general synthetic procedure is presented. The mechanism for the reaction is discussed on the basis of a linear stereochemical effect of the catalyst, the diastereoselectivity, and absolute stereochemistry of the isoxazolidines formed, and theoretical calculations of the 3,3'-diphenyl-BINOL-AlMe-nitrone intermediate.
1,3-DIPOLAR CYCLOADDITION OF C-BENZOYL-N-PHENYLNITRONE WITH DIHYDROFURAN DERIVATIVES. INVESTIGATION OF endo-exo STEREOSELECTIVITY
Fisera, Lubor,Dandarova, Miloslava,Kovac, Jaroslav,Gaplovsky, Anton,Patus, Juraj,Goljer, Igor
, p. 523 - 534 (2007/10/02)
C-Benzoyl-N-phenylnitrone (Ia) reacts with dihydrofuran derivatives (2,3-dihydro- and 2,5-dihydrofuran, 2,5-dimethoxy- and 2,5-diacetoxy-2,5-dihydrofuran) via 1,3-dipolar cycloaddition to give diastereoisomeric pair of exo- and endo-cycloadducts.The endo-
