iminium ion
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Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 6
Author(s):  
Mezna Saleh Altowyan ◽  
Saied M. Soliman ◽  
Matti Haukka ◽  
Nora H. Al-Shaalan ◽  
Aminah A. Alkharboush ◽  
...  

Hydrolysis/[3 + 2] cycloaddition/elimination cascades employed for the synthesis of unexpected tricyclic compound derived from isoquinoline. Reaction of ethylene derivative 1 with the isoquinoline ester iminium ion 2 in alkaline medium (MeOH/NEt3) under reflux for 1 h resulted in the formation of the fused pyrrolo[2,1-a]isoquinoline derivative 3. Its structure was elucidated by X-ray single crystal and other spectrophotometric tools. Hirshfeld calculations for 3 and its crystal structure analysis revealed the importance of the short O…H (19.1%) contacts and the relatively long H…C (17.1%), Cl…H (10.6%) and C…C (6.1%) interactions in the molecular packing. DFT calculations were used to compute the electronic and spectroscopic properties of the studied system. The studied compound has polar nature (3.5953 Debye). TD-DFT calculations assigned the shortest wavelength band (220 nm) to the HOMO−1→LUMO+2 (57%), HOMO−1→LUMO+4 (14%) mixed excitations. The calculated NMR chemical shifts correlated very well with the experimental data (R2 = 0.93–0.94).


Synlett ◽  
2021 ◽  
Author(s):  
Xiang Wu

Asymmetric organocatalysis is emerging as an elegant tool for accelerating chemical reactions and creating specific types of molecules. Chiral Brønsted acid catalysis is an important area of organocatalysis. Recently we described a chiral Brønsted acid (N-triflyl phosphoramide) catalyzed intramolecular iminium ion cyclization reaction of 2-alkenylbenzaldimines for the synthesis of chiral 1-aminoindenes and tetracyclic 1-aminoindanes in good yields and high enantioselectivities. The obtained 1-aminoindene can be utilized as useful synthetic intermediate for synthesis of (S)-rasagiline, an effective drug for the symptomatic treatment of Parkinson's disease. And the obtained tetracyclic 1-aminoindanes are the skeleton of homoisoflavanoid natural products such as brazilin.


2021 ◽  
Author(s):  
Linda Ofori Atta ◽  
Zhi Zhou ◽  
Gerard Roelfes

Artificial enzymes utilizing the genetically encoded non-proteinogenic amino acid p-aminophenylalanine (pAF) as catalytic residue are able to react with carbonyl compounds through an iminium ion mechanism, making reactions possible that have no equivalent in nature. Here, we report an in vivo biocatalytic cascade that is augmented with such an artificial enzyme catalyzed new-to-nature reaction. The artificial enzyme in this study is a pAF containing evolved variant of the Lactococcal multidrug resistance Regulator, designated LmrR_V15pAF_RMH, which efficiently converts in vivo produced benzaldehyde derivatives into the corresponding hydrazone products inside E. coli cells. These in vivo biocatalytic cascades comprising an artificial enzyme catalyzed reactions are an important step towards achieving a hybrid metabolism.


Synthesis ◽  
2021 ◽  
Author(s):  
Michael Keim ◽  
Medina Jasarevic ◽  
Ines Miller ◽  
Gerhard Maas

1,3-Bis(trifluoromethyl)prop-2-ene 1-iminium triflate salts were prepared for the first time and some synthetic applications as 1,3-biselectrophilic building blocks were established. They were found to react with dimethoxybenzenes or methylene-1,2-dioxybenzenes to furnish vinylogous trifluoroacetylaton products (4-aryl-1,1,1,5,5,5-hexafluoropent-3-en-2-ones) and 1-dialkylamino-1,3-bis(trifluoromethyl)-1H-indenes. With aniline and ring-substituted anilines, 2,4-bis(trifluoromethyl)quinolines were formed. An unusual 4H-pyran, formally a condensation product of the N,N-dimethyl-1,3-bis(trifluoromethyl)prop-2-en-1-iminium ion and its enaminone precursor, is also reported.


2021 ◽  
Author(s):  
Andreas Kunzendorf ◽  
Guangcai Xu ◽  
Mohammad Saifuddin ◽  
Thangavelu Saravanan ◽  
Gerrit J. Poelarends
Keyword(s):  

Author(s):  
Andreas Kunzendorf ◽  
Guangcai Xu ◽  
Mohammad Saifuddin ◽  
Thangavelu Saravanan ◽  
Gerrit J. Poelarends
Keyword(s):  

2021 ◽  
Author(s):  
Daniel Matheau-Raven ◽  
Darren J. Dixon

An iridium-catalyzed reductive three-component coupling reaction for the synthesis of medicinally relevant α-amino 1,3,4-oxadiazoles from abundant tertiary amides or lactams, carboxylic acids, and (N-isocyanimino) triphenylphosphorane, is described. Proceeding under mild conditions using (<1 mol%) Vaska’s complex (IrCl(CO)(PPh<sub>3</sub>)<sub>2</sub>) and tetramethyldisiloxane to access the key reactive iminium ion intermediates, a broad range of structurally complex α-amino 1,3,4-oxadiazole architectures were efficiently accessed from diverse carboxylic acid feedstock coupling partners. Extension to α-amino heterodiazole synthesis was readily achieved by exchanging the carboxylic acid coupling partner for C-, S-, or N-centered Brønsted acids, and provided rapid and modular access to these desirable, yet difficult-to-access, heterocycles. Furthermore, the high chemoselectivity of the catalytic reductive activation step allowed the late-stage functionalization of 10 drug molecules, including the synthesis of novel heterodiazole-fused drug-drug conjugates.<br>


2021 ◽  
Author(s):  
Daniel Matheau-Raven ◽  
Darren J. Dixon

An iridium-catalyzed reductive three-component coupling reaction for the synthesis of medicinally relevant α-amino 1,3,4-oxadiazoles from abundant tertiary amides or lactams, carboxylic acids, and (N-isocyanimino) triphenylphosphorane, is described. Proceeding under mild conditions using (<1 mol%) Vaska’s complex (IrCl(CO)(PPh<sub>3</sub>)<sub>2</sub>) and tetramethyldisiloxane to access the key reactive iminium ion intermediates, a broad range of structurally complex α-amino 1,3,4-oxadiazole architectures were efficiently accessed from diverse carboxylic acid feedstock coupling partners. Extension to α-amino heterodiazole synthesis was readily achieved by exchanging the carboxylic acid coupling partner for C-, S-, or N-centered Brønsted acids, and provided rapid and modular access to these desirable, yet difficult-to-access, heterocycles. Furthermore, the high chemoselectivity of the catalytic reductive activation step allowed the late-stage functionalization of 10 drug molecules, including the synthesis of novel heterodiazole-fused drug-drug conjugates.<br>


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