141565-14-2Relevant academic research and scientific papers
Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates
Ezawa, Tetsuya,Sohtome, Yoshihiro,Hashizume, Daisuke,Adachi, Masaya,Akakabe, Mai,Koshino, Hiroyuki,Sodeoka, Mikiko
supporting information, p. 9094 - 9104 (2021/07/01)
Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-keto ester enolates. Even in the presence of multiple equilibrating species, the catalytic protocol displays a wide substrate scope to access a range of CN-containing building blocks bearing adjacent stereocenters with high enantio- and diastereoselectivities. Our computational investigations suggest that the enantioselectivity is governed in the deprotonation process to form (Z)-Ni-enolates, while the unique syn addition is mainly controlled by weak noncovalent bonding interactions between the nitrone and ligand.
Catalytic migratory oxidative coupling of nitrones
Hashizume, Shogo,Oisaki, Kounosuke,Kanai, Motomu
supporting information; experimental part, p. 4288 - 4291 (2011/10/09)
A Cu(I)-catalyzed migratory oxidative coupling between nitrones and heterocycles or a methylamine is described. Selective C-C bond-formation proceeds through cleavage of two C(sp3)-H bonds concomitant with C=N double bond-migration. The reaction provides an alternating nitrone moiety, allowing for further synthetically useful transformations. Radical clock studies suggest that the nucleophilic addition of nitrones to an oxidatively generated carbocation is a key step.
Studies on tandem transesterification and intramolecular cycloaddition of nitrones. 1. Sequential bicyclization of α-methoxycarbonylnitrones with allyl alcohols
Tamura, Osamu,Okabe, Toshiyuki,Yamaguchi, Tatsuya,Gotanda, Kentoku,Noe, Katsuhide,Sakamoto, Masanori
, p. 107 - 118 (2007/10/02)
Treatment of α-methoxycarbonylnitrones with 5 equiv. of allyl alcohols in the presence of 1 equiv. of titanium tetraisopropoxide causes tandem transesterification, E,Z-isomerization of the nitrone moieties, and intramolecular cycloaddition to afford bicyclized compounds in one step. To reduce amounts of allyl alcohol, combined use of a catalytic amount of titanium tetraisopropoxide and molecular sieves 4A was found to be a more improved catalytic system. It was also found that reactions of (Z)-allyl alcohols with α-methoxycarbonylnitrone are more facile than those of (E)-allyl alcohols. This aspect was extended to geometry differentiated cycloaddition.
NOVEL E-Z EQUILIBRIUM OF N-ALKYL-α-ALKOXYCARBONYLNITRONE IN SOLUTION
Inouye, Yoshinobu,Hara, Junko,Kakisawa, Hiroshi
, p. 1407 - 1410 (2007/10/02)
Four N-alkyl-α-alkoxycarbonylnitrone were prepared and their NMR specra in C6D6, CDCl3, or CD3SOCD3 were measured.From the analyses of the spectra, it was found that the nitrones exhibited a facile equilibrium in all solvents used and E/Z ratio in equilibrium depended largely on the polarity of the solvent.
