Rhodamine spirolactam sensors operated by sulfur-cooperated metal complexation
摘要:
New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu2+ and Hg2+. A sensor carrying a dithiocarbonate group responded selectively to Hg2+ showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 10(4). Sensing was interrupted at the initial time of Hg2+ exposure due to the isomerization of imine and preferential metal bonding of two dithiocarbonate groups regardless of the main structure of rhodamine. The sensors exhibited the reversible and reproducible performance for Hg2+ sensing. (C) 2017 Elsevier B.V. All rights reserved.
Bifunctional building blocks in the Ugi-azide condensation reaction: a general strategy toward exploration of new molecular diversity
作者:Steven Gunawan、Christopher Hulme
DOI:10.1039/c3ob40900g
日期:——
1,5-Disubstituted tetrazoles are an important drug-like scaffold known for their ability to mimic the cis-amide bond conformation. The scaffold is readily accessible via substitution of the carboxylic acid component of the Ugi multi-component reaction (MCR) with TMSN3 in what is herein denoted the Ugi-azide reaction. This full paper presents a concise, novel, general strategy to access a plethora of new heterocylic scaffolds utilizing tethered aldo/keto-acids/esters in the Ugi-azide reaction followed by a ring closing event that generates novel highly complex bis-heterocyclic lactam-tetrazoles.
An Umpolung Oxa-[2,3] Sigmatropic Rearrangement Employing Arynes for the Synthesis of Functionalized Enol Ethers
作者:Rahul N. Gaykar、Malini George、Avishek Guin、Subrata Bhattacharjee、Akkattu T. Biju
DOI:10.1021/acs.orglett.1c00911
日期:2021.5.7
An oxa-[2,3] sigmatropicrearrangement involving arynes is reported featuring the umpolung of ketones, where the C═O bond polarity is reversed. The in situ-generated sulfur ylides from β-keto thioethers and arynes undergo efficient rearrangement allowing the facile and robust synthesis of functionalized enol ethers in high yields and excellent functional group compatibility. Preliminary mechanistic
A set of structurally diverse N-amino delta-lactams decorated with a 5-nitro-2-furyl moiety was synthesized using isocyanide-based multicomponent chemistry and evaluated for antibacterial activity. Three compounds displayed a selective and potent (MIC 22-33 mu M) inhibition of M. tuberculosis H(37)Rv strain growth, while other Gram-positive (MRSA and E. faecium) or Gram-negative (E. coli, P. aeruginosa, A. baumannii, K. pneumoniae) pathogens were not affected. The compounds also displayed moderate low cytotoxicity, as demonstrated in cell line viability assays. Several multidrug-and poly-resistant patient-derived M. tuberculosis strains were found to be susceptible to treatment with these compounds. The three most potent compounds share a significant structural similarity which provides a basis for further scaffold-hopping analog design. (C) 2017 Elsevier Ltd. All rights reserved.
Proline-like β-turn mimics accessed via Ugi reaction involving monoprotected hydrazines
A four-center, three-component Ugi-type reaction of a variety of keto acids, Boc- or Cbz-protected hydrazine, and isocyanides offers a simple and high yielding access to cyclic products containing an N-aminolactam unit. The latter are shown to form consistently an intramolecular hydrogen bond leading to a p-turn-like secondary structure. The possibility of integrating such N-aminolactam units (without disruption of the folded structure) into pseudotripeptide fragments is demonstrated. (C) 2010 Elsevier Ltd. All rights reserved.