Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis ...of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A3 couplings and C–H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses. Both racemic and enantioselective approaches have been reported. In the second part, an overview of the transformations of propargylamines into heterocyclic compounds such as pyrroles, pyridines, thiazoles, and oxazoles, as well as other relevant organic derivatives, is presented.
Current therapy against herpes simplex viruses (HSV) relies on the use of a few nucleoside antivirals such as acyclovir, famciclovir and valacyclovir. However, the current drugs are ineffective ...against latent and drug-resistant HSV infections. A series of amidinourea compounds, designed as analogues of the antiviral drug moroxydine, has been synthesized and evaluated as potential non-nucleoside anti-HSV agents. Three compounds showed micromolar activity against HSV-1 and low cytotoxicity, turning to be promising candidates for future optimization. Preliminary mode of action studies revealed that the new compounds act in an early stage of the HSV replication cycle, just after the viral attachment and the entry phase of the infection.
The chromo-fluorogenic detection of carbon monoxide in air has been achieved using a simple, inexpensive system based on ruthenium(II). This probe shows exceptional sensitivity and selectivity in ...its sensing behavior in the solid state. A color response visible to the naked eye is observed at 5 ppb of CO, and a remarkably clear color change occurs from orange to yellow at the onset of toxic CO concentrations (100 ppm) in air. Even greater sensitivity (1 ppb) can be achieved through a substantial increase in turn-on emission fluorescence in the presence of carbon monoxide, both in air and in solution. No response is observed with other gases including water vapor. Immobilization of the probe on a cellulose strip allows the system to be applied in its current form in a simple optoelectronic device to give a numerical reading and/or alarm.
The gold(I) complexes Au{S2CN(CH2CHCH2)2}(L) L = PPh3, PCy3, PMe3, CN t Bu, IDip are prepared from KS2CN(CH2CHCH2)2 and (L)AuCl. The compounds L2(AuCl)2 (L2 = dppa, dppf) yield ...(L2){AuS2CN(CH2CHCH2)2}2, while the cyclic complex (dppm){Au2S2CN(CH2CHCH2)2}OTf is obtained from dppm(AuCl)2 and AgOTf followed by KS2CN(CH2CHCH2)2. The compound Au2{S2CN(CH2CHCH2)2}2 is prepared from (tht)AuCl (tht = tetrahydrothiophene) and the diallyldithiocarbamate ligand. This product ring-closes with Ru(CHPh)Cl2(SIMes)(PCy3) to yield Au2(S2CNC4H6)2, whereas ring-closing of Au{S2CN(CH2CHCH2)2}(PR3) fails. Warming Au2{S2CN(CH2CHCH2)2}2 results in formation of gold nanoparticles with diallydithiocarbamate surface units, while heating Au2(S2CNC4H6)2 with NaBH4 results in nanoparticles with 3-pyrroline dithiocarbamate surface units. Larger nanoparticles with the same surface units are prepared by citrate reduction of HAuCl4 followed by addition of the dithiocarbamate. The diallydithiocarbamate-functionalized nanoparticles undergo ring-closing metathesis using Ru(CHC6H4O i Pr-2)Cl2(SIMes). The interaction between the dithiocarbamate units and the gold surface is explored using computational methods to reveal no need for a countercation. Preliminary calculations indicate that the Au–S interactions are substantially different from those established in theoretical and experimental studies on thiolate-coated nanoparticles. Structural studies are reported for Au{S2CN(CH2CHCH2)2}(PPh3) and Au2{S2CN(CH2CHCH2)2}2. In the latter, exceptionally short intermolecular aurophilic interactions are observed.
The new DO3A-derived dithiocarbamate ligand, DO3A-tBu-CS2K, is formed by treatment of the ammonium salt DO3A-tBuHBr with K2CO3 and carbon disulfide. DO3A-tBu-CS2K reacts with the ruthenium complexes ...cis-RuCl2(dppm)2 and Ru(CHCHC6H4Me-4)Cl(CO)(BTD)(PPh3)2 (BTD = 2,1,3-benzothiadiazole) to yield Ru(S2C-DO3A-tBu)(dppm)2+ and Ru(CHCHC6H4Me-4)(S2C-DO3A-tBu)(CO)(PPh3)2, respectively. Similarly, the group 10 metal complexes Pd(C,N-C6H4CH2NMe2)Cl2 and PtCl2(PPh3)2 form the dithiocarbamate compounds, Pd(C,N-C6H4CH2NMe2)(S2C-DO3A-tBu) and Pt(S2C-DO3A-tBu)(PPh3)2+, under the same conditions. The linear gold complexes Au(S2C-DO3A-tBu)(PR3) are formed by reaction of AuCl(PR3) (R = Ph, Cy) with DO3A-tBu-CS2K. However, on reaction with AuCl(tht) (tht = tetrahydrothiophene), the homoleptic digold complex Au(S2C-DO3A-tBu)2 is formed. Further homoleptic examples, M(S2C-DO3A-tBu)2 (M = Ni, Cu) and Co(S2C-DO3A-tBu)3, are formed from treatment of NiCl2·6H2O, Cu(OAc)2, or Co(OAc)2, respectively, with DO3A-tBu-CS2K. The molecular structure of Ni(S2C-DO3A-tBu)2 was determined crystallographically. The tert-butyl ester protecting groups of M(S2C-DO3A-tBu)2 (M = Ni, Cu) and Co(S2C-DO3A-tBu)3 are cleaved by trifluoroacetic acid to afford the carboxylic acid products, M(S2C-DO3A)2 (M = Ni, Cu) and Co(S2C-DO3A)3. Complexation with Gd(III) salts yields trimetallic M(S2C-DO3A-Gd)2 (M = Ni, Cu) and tetrametallic Co(S2C-DO3A-Gd)3, with r 1 values of 11.5 (Co) and 11.0 (Cu) mM–1 s–1 per Gd center. DO3A-tBu-CS2K can also be used to prepare gold nanoparticles, Au@S2C-DO3A-tBu, by displacement of the surface units from citrate-stabilized nanoparticles. This material can be transformed into the carboxylic acid derivative Au@S2C-DO3A by treatment with trifluoroacetic acid. Complexation with Gd(OTf)3 or GdCl3 affords Au@S2C-DO3A-Gd with an r 1 value of 4.7 mM–1 s–1 per chelate and 1500 mM–1 s–1 per object.
The synthesis of enantiomerically pure 1,3‐mercaptoalkanol volatile sulfur compounds through a one‐pot photo‐biocatalytic cascade reaction is described. Two new KRED biocatalysts with opposite ...enantioselectivity were discovered and proved to be efficient on a wide range of substrates. The one‐pot cascade reaction combining photocatalytic thio‐Michael addition with biocatalytic ketoreduction in an aqueous medium provides a green and sustainable approach to enantiomerically pure 1,3‐mercaptoalkanols in high yields with excellent enantioselectivity.
A dependable route to volatile products: A one‐pot cascade reaction combining photocatalytic thio‐Michael addition with biocatalytic ketoreduction in an aqueous medium was developed for the synthesis of enantiomerically pure 1,3‐mercaptoalkanols (see scheme). Two new ketoreductase (KRED) biocatalysts with opposite enantioselectivity were discovered and found to reduce a wide range of substrates efficiently.
A sustainable MAO-N biocatalyzed process for the synthesis of pyridines from aliphatic tetrahydropyridines (THP) has been developed. Pyridine compounds were synthesized under mild reaction conditions ...and with high conversion, exploiting MAO-N whole cells as aromatizing biocatalysts. The kinetic profile of the whole cell biocatalytic transformation was finally investigated via in situ 19F NMR.
A two-photon fluorescent probe based on a ruthenium(II) vinyl complex is capable of selectively detecting carbon monoxide in cells and ex vivo using mice with a subcutaneous air pouch as a model for ...inflammation. This probe combines highly selective and sensitive ex vivo detection of endogenous CO in a realistic model with facile, inexpensive synthesis, and displays many advantages over the widely used palladium-based systems.
The sensing of carbon monoxide (CO) using electrochemical cells or semiconducting metal oxides has led to inexpensive alarms for the home and workplace. It is now recognised that chronic exposure to ...low levels of CO also poses a significant health risk. It is perhaps surprising therefore that the CO is used in cell-signalling pathways and plays a growing role in therapy. However, the selective monitoring of low levels of CO remains challenging, and it is this area that has benefited from the development of probes which give a colour or fluorescence response. This feature article covers the design of chromo-fluorogenic probes and their application to CO sensing in air, solution and in cells.
The synthesis and biological evaluation of a series of phenanthroline-based visible-light-activated manganese(I) carbon-monoxide-releasing molecules (PhotoCORMs) against ESKAPE bacteria and bacterial ...biofilms is reported. Four carbonyl compounds of general formula fac-Mn(N∧N)(CO)3(L) have been synthesized and characterized. Despite being thermally stable in the absence of light, these PhotoCORMs readily release CO upon blue (435–450 nm) LED light irradiation as confirmed by spectrophotometric CO releasing experiments (Mb Assay). The antibacterial activity of the four PhotoCORMs has been investigated against a panel of ESKAPE bacteria. The compounds 1–3 were found to be effective antibacterials at low concentrations against multidrug-resistant Klebsiella pneumoniae and Acinetobacter baumannii when photoactivated with blue-light. In addition, the PhotoCORMs 1–2 were found to inhibit the formation of Klebsiella pneumoniae and Acinetobacter baumannii bacterial biofilms at low concentrations (MIC = 4–8 μg/mL), turning out to be promising candidates to combat antimicrobial resistance. The antibacterial and biofilm inhibitory effect of the PhotoCORMs is plausibly due to the release of CO as well as the formation of phenanthroline photo-by-products as revealed by spectroscopy and microbiology experiments.
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•Phenanthroline-based manganese(I) PhotoCORMs were synthesized and found to possess antibacterial activity.•PhotoCORMs release carbon monoxide (CO) when irradiated with visible light (blue or green).•PhotoCORMs show antibacterial activity against Gram negative bacteria when irradiated with blue LED light.•PhotoCORMs inhibit the formation of Klebsiella pneumoniae and Acinetobacter baumannii biofilms at low concentrations.•The release of CO and the formation of photo-by-products are responsible for the antibacterial and anti-biofilm activity.
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