The asymmetric synthesis of Szántay's amine (+)-2, the pivotal precursor for direct access to (+)-cycloclavine (1), is described for the first time in eleven steps with 19.7% overall yield from the commercially available 4-bromoindole. The strategy features an asymmetric induction by Ellman's sulfinimine and rhodium-catalysed isomerization of the C[double bond, length as m-dash]C bond.
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http://dx.doi.org/10.1039/c7cc08044a | DOI Listing |
Cureus
December 2024
Department of Regenerative Medicine, Rinaldi Fontani Institute, Florence, ITA.
This post-market clinical follow-up (PMCF) study evaluates the clinical effectiveness and safety of the external radio electric reprogramming for atrial fibrillation (EX-RER AF) protocol, a non-invasive regenerative medicine approach utilizing radio electric asymmetric conveyer (REAC) technology for managing paroxysmal atrial fibrillation (PAF). Administered with the REAC BENE mod 110 device (ASMED, Scandicci, Italy), the treatment involves a standardized procedure, with the asymmetric conveyor probe (ACP) positioned in the precordial area and fixed, unmodifiable parameters ensuring consistency and reproducibility. During a 36-month post-market clinical follow-up (PMCF), 20 patients with prior diagnoses of PAF underwent the protocol.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Guangxi Normal University, School of Chemistry and Pharmaceutical Sciences, 15 Yucai Road, 541004, Guilin, CHINA.
Skeletal editing represents an attractive strategy for adding complexity to a given molecular scaffold in chemical synthesis. Isodesmic reactions provide a complementary skeletal editing approach for the redistribution of chemical bonds in chemical synthesis. However, catalytic enantioselective isodesmic reaction is extremely scarce and enantioselective isodesmic reaction to synthesize atropisomeric compounds is unknown.
View Article and Find Full Text PDFChemistry
December 2024
Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, Kanpur, 208016, India.
Herein, we report a copper-catalyzed enantioselective formal (3+3) and (3+2) cycloaddition reaction of isatin-derived tertiary propargylic esters with N,N-dimethylbarbituric acid and 4-hydroxycoumarins, respectively. In this process, the tertiary propargylic ester serves as both C3- and C2-synthons, facilitating the synthesis of optically active spirooxindole-pyran and furan scaffolds featuring an all-carbon quaternary stereocenter. The reaction delivers these spirocyclic frameworks in good yields with high enantioselectivities.
View Article and Find Full Text PDFJ Org Chem
December 2024
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002, China.
A copper catalyzed enantioselective formal aza-Diels-Alder reaction of formed 1,2-diaza-1,3-dienes from α-halohydrazones and vinyl diazo compounds was described. The protocol provides a variety of optically enriched diazo-containing tetrahydropyridazines in moderate yields and with up to excellent enantioselectivities. The present methodologies utilize chiral oxazolines as the chiral ligands for asymmetric catalysis and feature mild reaction conditions, readily available substrates, and broad substrate scope.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462 066, India.
We envisioned a novel asymmetric strategy to access unsymmetrically substituted dimeric 2-oxindoles [(,)- and (,)-] for the total synthesis of calycanthidine (). The key to success is the development of efficient Pd(0)-catalyzed asymmetric sequential allylations [via a highly enantioselective [up to 94% enantiomeric excess (ee)] and diastereoselective (up to ∼13:1) process] of unsymmetrically protected dimeric 2-oxindoles at the 3,3' position [such as (,)- and (,)-]. Gratifyingly, a mixture of bis-ester (±)-, ester-carbonates (±)- and (±)-, and bis-carbonate could afford (,)- and (,)- in highly stereoselective fashion, thereby culminating in the total synthesis of (+)-calycanthidine [-()] and (-)-calycanthidine ().
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