83-25-0Relevant articles and documents
Electroselective and Controlled Reduction of Cyclic Imides to Hydroxylactams and Lactams
Bai, Ya,Shi, Lingling,Zheng, Lianyou,Ning, Shulin,Che, Xin,Zhang, Zhuoqi,Xiang, Jinbao
supporting information, p. 2298 - 2302 (2021/04/05)
An efficient and practical electrochemical method for selective reduction of cyclic imides has been developed using a simple undivided cell with carbon electrodes at room temperature. The reaction provides a useful strategy for the rapid synthesis of hydroxylactams and lactams in a controllable manner, which is tuned by electric current and reaction time, and exhibits broad substrate scope and high functional group tolerance even to reduction-sensitive moieties. Initial mechanistic studies suggest that the approach heavily relies on the utilization of amines (e.g., i-Pr2NH), which are able to generate α-aminoalkyl radicals. This protocol provides an efficient route for the cleavage of C-O bonds under mild conditions with high chemoselectivity.
Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
, p. 4327 - 4337 (2021/05/31)
A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
Nucleophilic Substitution at the Guanidine Carbon Center via Guanidine Cyclic Diimide Activation
An, Taeyang,Lee, Yan
supporting information, p. 9163 - 9167 (2021/11/24)
Despite the electron-deficient nature of the guanidine carbon centers, nucleophilic reactions at these sites have been underdeveloped because of the resonance stabilization of the guanidine group. We propose a guanidine C-N bond substitution strategy entailing the formation of guanidine cyclic diimide (GCDI) structures, which effectively destabilize the resonance structure of the guanidine group. In the presence of acid additives, the guanidine carbon center of GCDIs undergoes nucleophilic substitution reactions with various amines and alcohols.
Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
Longwitz, Lars,Werner, Thomas
supporting information, p. 2760 - 2763 (2020/02/05)
The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
Photoredox/Cobalt-Catalyzed C(sp3)-H Bond Functionalization toward Phenanthrene Skeletons with Hydrogen Evolution
Guo, Jia-Dong,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
supporting information, p. 9627 - 9632 (2020/12/21)
The first example of photoredox strategy for synthesis of phenanthrene skeletons through C(sp3)-H functionalization under external oxidant-free conditions is achieved. This transformation relies on the keto-enol tautomerism of 1,3 dicarbonyl moiety, i.e., the enol form of 1,3-dicarbonyl derivatives with relatively lower oxidation potential can be activated by the excited acridinium photocatalyst. The electron and proton eliminated from the substrate are immediately captured by a cobaloxime catalyst to exclusively afford a-carbonyl radical for highly substituted 10-phenanthrenols in good to excellent yields.
Cu-catalyzed N-3-Arylation of Hydantoins Using Diaryliodonium Salts
Neerbye Berntsen, Linn,Nova, Ainara,Wragg, David S.,Sandtorv, Alexander H.
, p. 2687 - 2691 (2020/04/10)
A general Cu-catalyzed, regioselective method for the N-3-arylation of hydantoins is described. The protocol utilizes aryl(trimethoxyphenyl)iodonium tosylate as the arylating agent in the presence of triethylamine and a catalytic amount of a simple Cu-salt. The method is compatible with structurally diverse hydantoins and operates well with neutral aryl groups or aryl groups bearing weakly donating/withdrawing elements. It is also applicable for the rapid diversification of pharmaceutically relevant hydantoins.
Ru-Catalyzed Selective C-H Bond Hydroxylation of Cyclic Imides
Yuan, Yu-Chao,Bruneau, Christian,Dorcet, Vincent,Roisnel, Thierry,Gramage-Doria, Rafael
, p. 1898 - 1907 (2019/02/05)
We report on cyclic imides as weak directing groups for selective monohydroxylation reactions using ruthenium catalysis. Whereas acyclic amides are known to promote the hydroxylation of the C(sp2)-H bond enabling five-membered ring ruthenacycle intermediates, the cyclic imides studied herein enabled the hydroxylation of the C(sp2)-H bond via larger six-membered ruthenacycle intermediates. Furthermore, monohydroxylated products were exclusively obtained (even in the presence of overstoichiometric amounts of reagents), which was rationalized by the difficulty to accommodate coplanar intermediates once the first hydroxyl group was introduced into the substrate. The same reactivity was observed in the presence of palladium catalysts.
Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
Antonchick, Andrey P.,Manna, Srimanta
, p. 3094 - 3098 (2018/09/14)
We developed an operationally simple method for the direct use of biomass-derived chemical entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple variations in the reaction conditions. This work is based on an unprecedented catalytic system and represents a straightforward application of biomass as a reducing reagent in chemical reactions.
Iron(III) Chloride/Phenylsilane-Mediated Cascade Reaction of Allyl Alcohols with Maleimides: Synthesis of Poly-Substituted γ-Butyrolactones
Zhang, Hua,Zhan, Xiao-Yu,Chen, Xu-Ling,Tang, Lei,He, Shuai,Shi, Zhi-Chuan,Wang, Yu,Wang, Ji-Yu
, p. 4919 - 4925 (2019/11/03)
A iron-catalyzed free radical cascade reaction of allyl alcohols with N-substituted maleimides for accessing poly-substituted γ-butyrolactones has been developed. In this protocol, various allyl alcohols can open N-substituted maleimide rings to form allyl ester intermediates, and the allyl ester intermediates can be converted into an allyl ester alkyl radicals and undergo intramolecular free radical addition cyclization to form a polysubstituted γ-butyrolactones. In this protocol, spiro γ-butyrolactone compounds can be also synthesized. Meanwhile, the strategy could be applied to further construct a fully substituted tetrahydrofuran. The reaction is not sensitive to oxygen or moisture and has been performed on gram-scale. (Figure presented.).
Simple and efficient synthesis of N-alkyl and N-aryl succinimides in hot water
Bozdo?an, Burcu,Er?at?r, Mehmet,Demirkol, Onur,Akba?lar, Dilek,Giray, E. Sultan
, p. 217 - 223 (2017/01/22)
A new, simple synthesis of succinimides is described. The reactions were carried out under the ultimate green conditions excluding both catalyst and organic solvent by applying simple stirring at 100 °C. A wide variety of N-susbstituted succinimides have been prepared in high yields by using succinic acid and primary amines in hot water. Yield of N-alkyl substituted succinimides were found to be higher than those of N-aryl substituted succinimides.
