31053-10-8Relevant academic research and scientific papers
Powerful solvent effect of water in radical reaction: Triethylborane-induced atom-transfer radical cyclization in water
Yorimitsu,Nakamura,Shinokubo,Oshima,Omoto,Fujimoto
, p. 11041 - 11047 (2000)
Triethylborane-induced atom-transfer radical cyclization of iodo acetals and iodoacetates in water is described. Radical cyclization of iodo acetal proceeded smoothly both in aqueous methanol and in water. Atom-transfer radical cyclization of allyl iodoac
Merging Halogen-Atom Transfer (XAT) and Copper Catalysis for the Modular Suzuki-Miyaura-Type Cross-Coupling of Alkyl Iodides and Organoborons
Górski, Bartosz,Leonori, Daniele,Zhang, Zhenhua
supporting information, (2022/02/01)
We report here a mechanistically distinct approach to achieve Suzuki-Miyaura-type cross-couplings between alkyl iodides and aryl organoborons. This process requires a copper catalyst but, in contrast with previous approaches based on palladium and nickel
Photochemical Decarboxylative C(sp3)-X Coupling Facilitated by Weak Interaction of N-Heterocyclic Carbene
Chen, Kun-Quan,Wang, Zhi-Xiang,Chen, Xiang-Yu
, p. 8059 - 8064 (2020/11/02)
While N-hydroxyphthalimide (NHPI) ester has emerged as a powerful reagent as an alkyl radical source for a variety of C-C bond formations, the corresponding C(sp3)-N bond formation is still in its infancy. We demonstrate herein transition-metal-free decarboxylative C(sp3)-X bond formation enabled by the photochemical activity of the NHPI ester-NaI-NHC complex, giving primary C(sp3)-(N)phth, secondary C(sp3)-I, or tertiary C(sp3)-(meta C)phth coupling products. The primary C(sp3)-(N)phth coupling offers convenient access to primary amines.
Asymmetric Baeyer - Villiger oxidations of 4-mono- and 4,4-disubstituted cyclohexanones by whole cells of engineered Escherichia coli
Mihovilovic,Chen,Wang,Kyte,Rochon,Kayser,Stewart
, p. 733 - 738 (2007/10/03)
Whole cells of an Escherichia coli strain that overexpresses Acinetobacter sp. NCIB 9871 cyclohexanone monooxygenase have been used for the Baeyer-Villiger oxidations of a variety of 4-mono- and 4,4-disubstituted cyclohexanones. In cases where comparisons were possible, this new biocatalytic reagent provided lactones with chemical yields and optical purities that were comparable to those obtained from the purified enzyme or a strain of bakers' yeast that expresses the same enzyme. The efficient production of cyclohexanone monooxygenase in the E. coli expression system (ca. 30% of total soluble protein) allowed these oxidations to reach completion in approximately half the time required for the engineered bakers' yeast strain. Surprisingly, 4,4-disubstituted cyclohexanones were also accepted by the enzyme, and the enantioselectivities of these oxidations could be rationalized by considering the conformational energies of bound substrates along with the enzyme's intrinsic enantioselectivity. The enzyme expressed in E. coli cells also oxidized several 4-substituted cyclohexanones bearing polar substituents, often with high enantioselectivities. In the case of 4-iodocyclohexanone, the lactone was obtained in > 98% ee and its absolute configuration was assigned by X-ray crystallography. The crystal belongs to the monoclinic P21 space group with a = 5.7400(10), b = 6.1650(10), c = 11.377(2) A, b = 99.98(2)°, and Z = 2. Taken together, these results demonstrate the utility of an engineered bacterial strain in delivering useful chiral building blocks in an experimentally simple manner.
Atom Transfer Cyclization Reactions of α-Iodo Esters, Ketones, and Malonates: Examples of Selective 5-Exo, 6-Endo, 6-Exo, and 7-Endo Ring Closures
Curran, Dennis P.,Chang, Chi-Tai
, p. 3140 - 3157 (2007/10/02)
The preparation and free-radical cyclization reactions of unsaturated α-iodo esters, ketones, and malonates have been investigated.For example, sunlamp irradiation of methyl 2-iodo-6-heptenoate in benzene in the presence of 10 mol percent hexabutylditin produces methyl 2-(iodomethyl)cyclopentanecarboxylate (cis and trans) and methyl 3-iodocyclohexanecarboxylate in a ratio of 93/7 in a combined yield of 86percent.The γ-iodo carbonyl products can either be isolated (in most cases) or converted in situ to deiodinated products (with Bu3SnH) or lactones (by heating).Five-, six-, or seven-membered rings selectively form, depending on chain length and alkene substitution.Terminal alkene substituents favor exo cyclization while internal alkene substituents promote endo cyclization.A preference for endo closure is also observed when there is a carbonyl group "inside" the forming ring.A detailed analysis of reaction rates indicates that these isomerizations proceed by an iodine atom transfer chain mechanism, and thus the observed selectivities are due to the kinetic substituent effects.The results contrast the thermodynamically controlled hydrogen atom transfer cyclizations of Julia.A new procedure for the removal of tin byproducts is described.
