Rhodium-catalyzed asymmetric hydrogenation of tetrasubstituted β-acetoxy-α-enamido esters and efficient synthesis of droxidopa

2017 ◽  
Vol 53 (58) ◽  
pp. 8136-8139 ◽  
Author(s):  
Yu-Qing Guan ◽  
Min Gao ◽  
Xu Deng ◽  
Hui Lv ◽  
Xumu Zhang
Keyword(s):  
Asymmetric Hydrogenation ◽  
Efficient Synthesis ◽  
Efficient Route ◽  
High Yields

Rhodium-catalyzed asymmetric hydrogenation of challenging tetrasubstituted β-acetoxy-α-enamido esters was developed, giving chiral β-acetoxy-α-amido esters in high yields with excellent enantioselectivities. This protocol provides an efficient route for the synthesis of droxidopa.

scholarly journals Efficient Synthesis of α-Branched Purine-Based Acyclic Nucleosides: Scopes and Limitations of the Method

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4307
Author(s):  
Jan Frydrych ◽  
Lenka Poštová Slavětínská ◽  
Martin Dračínský ◽  
Zlatko Janeba
Keyword(s):  
Acetic Anhydride ◽  
Room Temperature ◽  
Side Chain ◽  
Efficient Synthesis ◽  
Purine Derivatives ◽  
Aliphatic Side Chain ◽  
Acyclic Nucleosides ◽  
Efficient Route ◽  
High Yields ◽  
Trimethylsilyl Trifluoromethanesulfonate

An efficient route to acylated acyclic nucleosides containing a branched hemiaminal ether moiety is reported via three-component alkylation of N-heterocycle (purine nucleobase) with acetal (cyclic or acyclic, variously branched) and anhydride (preferentially acetic anhydride). The procedure employs cheap and easily available acetals, acetic anhydride, and trimethylsilyl trifluoromethanesulfonate (TMSOTf). The multi-component reaction is carried out in acetonitrile at room temperature for 15 min and provides moderate to high yields (up to 88%) of diverse acyclonucleosides branched at the aliphatic side chain. The procedure exhibits a broad substrate scope of N-heterocycles and acetals, and, in the case of purine derivatives, also excellent regioselectivity, giving almost exclusively N-9 isomers.

scholarly journals Efficient synthesis of chiral 2,3-dihydro-benzo[b]thiophene 1,1-dioxides via Rh-catalyzed hydrogenation

2019 ◽  
Vol 10 (8) ◽  
pp. 2507-2512 ◽  
Author(s):  
Gongyi Liu ◽  
Heng Zhang ◽  
Yi Huang ◽  
Zhengyu Han ◽  
Gang Liu ◽  
...  
Keyword(s):  
Asymmetric Hydrogenation ◽  
Efficient Synthesis ◽  
High Yields

Rh-Catalyzed asymmetric hydrogenation of substituted benzo[b]thiophene 1,1-dioxides was successfully developed. Both aromatic and alkyl substituted benzo[b]thiophene 1,1-dioxide substrates worked well with high yields and excellent enantioselectivities.

An Efficient Synthesis of 2-Substituted Quinazolin-4(3H)-ones by Using Recyclable Wang Resin Supported Sulfonic Acid Catalyst

2020 ◽  
Vol 17 ◽  
Author(s):  
Kalyani K. ◽  
Srinivasa Reddy Kallam
Keyword(s):  
Sulfonic Acid ◽  
Functional Group ◽  
Acid Catalyst ◽  
Sulphonic Acid ◽  
Isatoic Anhydride ◽  
Efficient Synthesis ◽  
Wang Resin ◽  
Polymer Supported ◽  
High Yields

Abstract:: An efficient synthesis of 2-substituted Quinazolin-4(3H)-ones has been developed from isatoic anhydride with various amidoximes by using recyclable polymer supported sulphonic acid catalyst. Excellent functional group compatibil-ity and high yields are the important features of this protocol.

scholarly journals PEG-embedded KBr3: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

2011 ◽  
Vol 7 ◽  
pp. 1334-1341 ◽  
Author(s):  
Sanny Verma ◽  
Suman L Jain ◽  
Bir Sain
Keyword(s):  
Coupling Reaction ◽  
Recyclable Catalyst ◽  
Efficient Synthesis ◽  
Molecular Bromine ◽  
Keto Ester ◽  
One Step ◽  
High Yields ◽  
Multicomponent Coupling ◽  
Three Component Coupling

PEG-embedded potassium tribromide ([K+PEG]Br3 −) was found to be an efficient and recyclable catalyst for the synthesis of functionalized piperidines in high yields in a one step, three component coupling between aldehyde, amine and β-keto ester. At the end of the reaction the [K+PEG]Br3 − was readily regenerated from the reaction mixture by treating the residue containing [K+PEG]Br− with molecular bromine.

scholarly journals A two step synthesis of a key unit B precursor of cryptophycins by asymmetric hydrogenation

2011 ◽  
Vol 7 ◽  
pp. 243-245 ◽  
Author(s):  
Benedikt Sammet ◽  
Mathilde Brax ◽  
Norbert Sewald
Keyword(s):  
Asymmetric Hydrogenation ◽  
Synthetic Route ◽  
Reaction Conditions ◽  
High Yields

A novel highly enantioselective two step access to a unit B precursor of cryptophycins in good yields from commercially available starting materials has been developed. The key step is an asymmetric hydrogenation using the commercially available [(COD)Rh-(R,R)-Et-DuPhos]BF4 catalyst. The synthetic route provides the advantage of less synthetic steps, proceeds with high yields and enantioselectivity, and avoids hazardous reaction conditions.

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.

scholarly journals A Simple and Efficient Synthesis of Highly Substituted Indeno[1,2-b]pyrrole and Acenaphtho[1,2-b]pyrrole Derivatives by Tandem Three-Component Reactions

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 3031 ◽  
Author(s):  
Xiaodong Tang ◽  
Songlei Zhu ◽  
Ying Ma ◽  
Ren Wen ◽  
Lanqi Cen ◽  
...  
Keyword(s):  
Environmentally Benign ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Dicarbonyl Compounds ◽  
Pyrrole Derivatives ◽  
Three Component Reaction ◽  
High Yields ◽  
Operational Simplicity

A green, convenient and tandem procedure for the efficient synthesis of highly substituted indeno[1,2-b]pyrrole and acenaphtho[1,2-b]pyrrole derivatives by domino three-component reaction of tryptamine/benzylamine, 1,3-dicarbonyl compounds and ninhydrin/ acenaphthenequinone is described. The significant features of this procedure were characterized by mild reaction conditions, high yields, operational simplicity and it being environmentally benign.

scholarly journals Zn(L-proline)2: An efficient and reusable organocatalyst for the synthesis of polyfunctionally substituted pyrans and 2-amino-4-aryl-8-oxo-4,8-dihydropyrano[3,2-b]pyran derivatives

2019 ◽  
Vol 10 (2) ◽  
pp. 166-170 ◽  
Author(s):  
Fatma Ahmed Abo Elsoud ◽  
Mohamed Abd-Elmonem ◽  
Mohamed Abo Elsebaa ◽  
Kamal Usef Sadek
Keyword(s):  
Kojic Acid ◽  
Aromatic Aldehydes ◽  
Efficient Synthesis ◽  
Atom Economy ◽  
Short Reaction Time ◽  
Biologically Relevant ◽  
Three Component Reaction ◽  
High Yields ◽  
Organometallic Catalyst ◽  
Work Up

Efficient synthesis of non-annulated 2-amino-4H-pyrans and 2-amino-8-oxo-4,8-dihydropyrano[3,2-b]pyran derivatives, which are biologically relevant heterocycles is achieved, utilizing a domino three-component reaction of ethyl acetoacetate or kojic acid with aromatic aldehydes and malononitrile catalyzed by Zn(L-proline)2 as reusable organometallic catalyst. The process exhibits high atom economy, short reaction time, simple work up, high yields and environmentally friendly nature. Excellent yields of the targeted molecules have been obtained.

Cinchona alkaloid and di-tert-butyldicarbonate–DMAP promoted efficient synthesis of (E)-nitroolefins

RSC Advances ◽  
2016 ◽  
Vol 6 (59) ◽  
pp. 54495-54502 ◽  
Author(s):  
Nataraj Poomathi ◽  
Paramasivan T. Perumal
Keyword(s):  
Cinchona Alkaloid ◽  
Efficient Synthesis ◽  
Metal Free ◽  
High Yields

A simple and efficient metal-free methodology for the synthesis of β-nitroolefins has been developed from arylidinemalononitrile using bifunctional cinchona alkaloid along with di-tert-butyldicarbonate–DMAP in high yields with total selectivity.

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