scholarly journals Enantioselective cyanation via radical-mediated C–C single bond cleavage for synthesis of chiral dinitriles

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Tao Wang ◽  
Yi-Ning Wang ◽  
Rui Wang ◽  
Bo-Chao Zhang ◽  
Chi Yang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bond Cleavage ◽  
Catalyst Loading ◽  
Small Ring ◽  
Single Bond ◽  
Asymmetric Transformations ◽  
Mild Conditions ◽  
Ring Opening Reaction ◽  
High Yields ◽  
Low Catalyst Loading

AbstractRing-opening reaction via selective cleavage of C–C bond is known as a powerful strategy for construction of complex molecules. Complementary to the ionic process focusing on mostly small ring systems, radical-mediated C–C bond cleavage offers a solution for further diverse enantioselective functionalization benefited from its mild conditions, whereas such asymmetric transformations are still limited to three-membered rings so far. Herein, we describe radical-mediated ring-opening and enantioselective cyanation of four- and five-membered cycloketone oxime esters to access chiral 1,5- and 1,6-dinitriles. Employment of dual photoredox/copper catalysis is essential for the asymmetric ring-opening cyanation of cyclopentanone oxime esters. Both reactions proceed under mild conditions giving chiral dinitriles in high yields and enantioselectivity with low catalyst loading and broad substrate scope. The products dinitriles can be converted to valuable optically active diamides and diamines. Mechanistic studies indicate that the benzylic radical generated via C–C single bond cleavage is involved in the catalytic cycle.

Lipase catalyzed 1,2-addition of thiols to imines under mild conditions

2018 ◽  
Vol 42 (3) ◽  
pp. 1642-1645 ◽  
Author(s):  
Tábata B. Albuquerque ◽  
Caren D. G. da Silva ◽  
Aline R. de Oliveira ◽  
Beatriz F. dos Santos ◽  
Beatriz A. L. da Silva ◽  
...  
Keyword(s):  
Catalyst Loading ◽  
Mild Conditions ◽  
High Yields ◽  
Low Catalyst Loading

PPL, chymosin and BSA as efficient biocatalysts (low catalyst loading, high yields) in an eco-friendly synthesis of N,S-acetals.

Three-Component Synthesis of 4-Arylidene-3-alkylisoxazol-5(4H)-ones in the presence of potassium 2,5-dioxoimidazolidin-1-ide

2021 ◽  
Vol 25 ◽  
Author(s):  
Neda Reihani ◽  
Hamzeh Kiyani
Keyword(s):  
Ethylene Glycol ◽  
Ethyl Acetoacetate ◽  
Reaction Medium ◽  
Hydroxylamine Hydrochloride ◽  
Aromatic Aldehydes ◽  
Catalyst Loading ◽  
Efficient Synthesis ◽  
Current Process ◽  
High Yields ◽  
Low Catalyst Loading

: An efficient synthesis of 4-arylidene-3-alkylisoxazole-5(4H)-ones has been implemented via the three-component cyclocondensation of aryl(heteroaryl)aldehydes with hydroxylamine hydrochloride and β-ketoesters. The potassium 2,5-dioxoimidazolidin-1-ide has been introduced as the new organocatalyst to facilitate of this heterocyclization. In the current process, three starting materials, including substituted benzaldehydes/heterocyclic aromatic aldehydes, hydroxylamine hydrochloride, and ethyl acetoacetate/propyl acetoacetate/butyryl acetoacetate have been successfully used for the synthesize of the number of substituted isoxazole-5(4H)-ones in good to high yields in ethylene glycol as a green reaction medium at 80 ºC. The low catalyst loading is also a main advantage over the some reported catalysts.

Palladium-catalyzed Sonogashira coupling of amides: access to ynones via C–N bond cleavage

2016 ◽  
Vol 52 (81) ◽  
pp. 12076-12079 ◽  
Author(s):  
Ming Cui ◽  
Hongxiang Wu ◽  
Junsheng Jian ◽  
Hui Wang ◽  
Chao Liu ◽  
...  
Keyword(s):  
Functional Group ◽  
Bond Cleavage ◽  
Catalyst Loading ◽  
Sonogashira Coupling ◽  
Broad Array ◽  
Palladium Catalyzed ◽  
Low Catalyst Loading

The first palladium-catalyzed Sonogashira coupling of amides has been developed, which proceeds via a selective cleavage of the N-acylsaccharin C–N bond. The protocol is mild, highly functional group tolerant and can be efficiently employed in the synthesis of a broad array of ynones in 48–98% yields under low catalyst loading and Cu-free conditions.

Ligand-Free Nickel-Catalyzed Reductive Allylic Defluorinative Cross-Coupling of α-Trifluoromethyl Alkenes with Epoxides

Synlett ◽  
2020 ◽  
Author(s):  
Chuan Wang ◽  
Zhiyang Lin ◽  
Yun Lan
Keyword(s):  
Ring Opening ◽  
Cross Coupling ◽  
Proton Donor ◽  
Mild Conditions ◽  
Ligand Free ◽  
High Yields ◽  
Radical Type

We report a reductive allylic defluorinative reaction of α-trifluoromethyl alkenes with terminal epoxides, which consists of an iodide-mediated regioselective ring opening and a nickel-catalyzed radical-type cross-coupling, providing diverse tertiary gem-difluorobishomoallylic alcohols in moderate to high yields. Notably, this reaction is conducted under mild conditions and requires no external ligand or proton donor.

scholarly journals Decarbonylation through Aldehydic C–H Bond Cleavage by a Cationic Iridium Catalyst

Synlett ◽  
2019 ◽  
Vol 30 (08) ◽  
pp. 972-976 ◽  
Author(s):  
Tomohiko Shirai ◽  
Kazuki Sugimoto ◽  
Masaya Iwasaki ◽  
Ryuki Sumida ◽  
Harunori Fujita ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Catalyst System ◽  
Mild Conditions ◽  
Iridium Catalyst ◽  
Reaction Proceeds ◽  
High Yields

We report the decarbonylation of aldehydes through an aldehydic C–H bond cleavage catalyzed by a cationic iridium/bisphosphine catalyst. The reaction proceeds under relatively mild conditions to give the corresponding hydrocarbon products in moderate to high yields. In addition, this cationic iridium catalyst system can be applied to an asymmetric hydroacylation of ketones.

scholarly journals Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

2012 ◽  
Vol 8 ◽  
pp. 699-704 ◽  
Author(s):  
Saet Byeol Woo ◽  
Dae Young Kim
Keyword(s):  
Michael Addition ◽  
Catalyst Loading ◽  
High Yields ◽  
Low Catalyst Loading

The highly enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes, promoted by binaphthyl-modified chiral bifunctional organocatalysts is described. This reaction afforded the chiral functionalized naphthoquinones in high yields (81–95%) and excellent enantioselectivities (91–98% ee) under low catalyst loading (1 mol %).

Au-catalyzed ring-opening reactions of 2-(1-alkynyl-cyclopropyl)pyridines with nucleophiles

2015 ◽  
Vol 13 (17) ◽  
pp. 4855-4858 ◽  
Author(s):  
Ren-Rong Liu ◽  
Shi-Chun Ye ◽  
Chuan-Jun Lu ◽  
Bin Xiang ◽  
Jianrong Gao ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bond Cleavage ◽  
Mild Conditions ◽  
Efficient Access ◽  
Ring Opening Reactions ◽  
Novel Method

A novel method for the C–C bond cleavage of cyclopropanes was developed by gold-catalyzed cycloisomerization of 2-(1-alkynyl-cyclopropyl)pyridine with nucleophiles, which provides efficient access to structurally diverse indolizines under mild conditions.

Potassium Hydroxide Catalysed Intermolecular Aza-Michael Addition of 3-Cyanoindole to Aromatic Enones

Synlett ◽  
2017 ◽  
Vol 28 (10) ◽  
pp. 1227-1231 ◽  
Author(s):  
Jingya Yang ◽  
Tianyuan Li ◽  
Hongyan Zhou ◽  
Nana Li ◽  
Dongtai Xie ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Michael Addition ◽  
Potassium Hydroxide ◽  
Michael Reaction ◽  
Pharmaceutical Compounds ◽  
Catalyst Loading ◽  
Good Substrate ◽  
Substrate Tolerance ◽  
High Yields ◽  
Low Catalyst Loading

Indole is one of the utmost important heterocycles as it is an essential nucleus of many pharmaceutical compounds. Its aza-Michael reaction, however, is underdeveloped because of the moiety’s inherent characteristics. Here, a potassium hydroxide catalysed intermolecular aza-Michael reaction of 3-cyanoindole with aromatic enones is described. A variety of chalcone derivatives are well tolerated and afford the corresponding N-adducts in moderate to high yields. The use of a cheap catalyst, low catalyst loading, mild reaction temperature, and good substrate tolerance make this procedure a direct and facile method for the preparation of N1-functionalized indoles.

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