•Metal free synthesis of 4-aryl-6-hydroxy-2H-Pyran-2-cyanomethylenes.•X-ray study revealed rare plausible peri oxygen-oxygen interactions between O2 and O3.•Unique homodimer intermolecular H-bonding ...interaction between the nitrogen and hydroxyl group.
The synthesis of 4-aryl-2H-pyran-2-ones 7 was accomplished by rearrangement of 6-aryl-2H-pyran-ones 5 with ethyl cyanoacetate 6 in the presence of a base in DMF at room temperature. The reaction products were achieved in good yields. The reaction products were characterized by their spectroscopic analysis. The structure of compound 7a was confirmed by its single crystal X-ray analysis. Moreover, single crystal X-ray study of compound 7a showed rare plausible peri oxygen-oxygen interactions between O2 and O3. Further compound 7a showed homodimer intermolecular H-bonding interactions between nitrogen and OH groups along with a-b plane. These non-covalent interactions stabilized compound 7a in the crystalline state.
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A convenient approach for the synthesis of functionalized 1,3-bis(heteroaryl)benzenes 6 and 9 is describe via carbanion-induced ring transformation reaction of 6-heteroaryl-2H-pyran-2-ones 4 and 7. ...The ring transformation of 6-heteroaryl-2H-pyran-2-one 4 and 7 with heteroarylketones 5 and 8 was performed using KOH as base in DMF at ambient temperature. The ring transform products 6 and 9 were isolated in good to excellent yields under mild reaction condition. All the synthesized compounds were characterized by 1H NMR, 13C NMR, GCMS and IR followed by CHNS analysis. Additionally, the photophysical behaviour of the synthesized compounds was studied by using UV–vis and fluorescence spectroscopy. Compounds 6a-l showed the emission maxima in the range of 411–461 nm while compounds 9a-k showed the emission maxima in the range of 437–508 nm. The band gap of synthesized compounds 6a-l and 9a-k were calculated from their UV–vis data. The band gap of compounds 6a-l was obtained from 3.91 to 4.37 eV while 3.39–3.56 eV in case of the compounds 9a-k. Moreover, the thermo-gravimetric analysis (TGA) of compound 9f was carried out to check the thermal stability.
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•Metal-free synthesis of functionalized 1,3-bis(heteroaryl)benzenes 6 and 9 was achieved by ring transformation reaction.•All the synthesized compounds were characterized by 1H NMR, 13C NMR, GCMS and IR followed by CHNS analysis.•The photophysical behaviour of the synthesized compounds was studied by using UV–vis and fluorescence spectroscopy.•Compounds 6a-l showed the emission maxima from 411 nm to 461 nm while compounds 9a-k showed from 437 nm to 508 nm.•Thermal stability of compound 9f was evaluated by thermo-gravimetric analysis (TGA).
A simple yet innovative approach for the construction of multi-substituted allylbenzenes 14, 16 and 18 with 'donor-acceptor' functionalities has been delineated through base-mediated ring ...transformation of 6-aryl-2H-pyran-2-ones 13, 15 and 17 respectively with commercially available 5-hexen-2-one 11 as carbanion source. The reactions were carried out at room temperature without using any catalyst or organometallic reagents with excellent functional group tolerance. Moreover, the present method is possible alternate route to access allylbenzenes apart from usual metal-catalyzed cross-coupling reactions.
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Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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•The first stereoselective non-biological synthesis of chiral 6-pentyl-2H-pyran-2-ones.•Confirmation of the absolute configuration of the chiral 6PP metabolites.•Selective furanose ...acetolysis.•Stereoselective allylation of an acetal.•Palladium-catalyzed β-elimination of acetic acid.
The total synthesis of three chiral 6-pentyl-2H-pyran-2-ones (metabolites of Trichoderma spp and Penicillium isolates) is reported. With the preservation of the configurational integrity of one stereogenic center (2S of the chiron 7,3-LXF), these total syntheses permitted the confirmation of the absolute configuration of two of them (1 and 2). Since the optical rotation data of one natural metabolite was not disclosed in the original publication, its enantiopure synthesis (R-3) did not permitted either the confirmation or revision of the absolute configuration. The present approach involves a selective furanose acetolysis, a stereoselective allylation of an intermediate acetal and a Pd-catalyzed β-elimination reaction.
We are reporting a simple and efficient synthesis of highly functionalized aniline by the reaction of 2H‐pyran‐2‐ones and benzyl cyanide in presence of sodamide in dioxane under reflux conditions. ...Various 4‐sec.amino‐2H‐pyran‐2‐ones, 4‐methylsulfanyl‐2H‐pyran‐2‐ones and 2‐oxobenzohchromones were used as a substrate. Further, synthetic application of obtained arylated aniline was carried out to afford multifunctional carbazoles (13). 2′′‐Bromo‐1,1′ : 2′,1′′‐teraryl‐3′‐amines (6) and 4‐(2‐bromoarylyl)‐9,10‐dihydrophenanthren‐3‐amines (11) was used to demonstrate the the synthesis of carbazoles. The structure of isolated product 11 d was ascertained by spectroscopic and single crystal X‐ray diffraction analyses. We have explained the role of nonpolar solvents in the synthesis of arylated aniline.
Sodamide‐mediated synthesis of arylated anilines in nonpolar solvent 1,4‐dioxane is reported. Functionalized carbazoles were also afforded from suitably functionalized arylated anilines.
This paper describes a facile one‐pot synthesis of highly functionalized 2H‐pyran‐2‐ones and phenols through a base‐promoted annulation of readily available β‐chlorovinyl ketones with various active ...methylene compounds. Conjugate addition of electron‐withdrawing group substituted acetates to allenone intermediates and direct conjugate addition of β‐diketones to β‐chlorovinyl ketones reveal versatile electrophilic pathways of β‐chlorovinyl ketones under different reaction conditions. In particular, cyclocondensation is regiospecific for 3,5‐disubstituted phenols. Moreover, the utility of 3+3 cyclocondensation is further illustrated by the concise synthesis of benzofuran derivative and penta‐ or hexa‐substituted phenol construction.
This paper describes a facile one‐pot synthesis of highly functionalized 2H‐pyran‐2‐ones and a regiospecific construction of 3,5‐disubstituted phenols via base‐promoted annulation of readily available β‐chlorovinyl ketones with various active methylene compounds. The detailed experimental studies demonstrated that versatile electrophilic pathways of β‐chlorovinyl ketones could be observed by using different nucelophilic species.
Two new rare α‐pyrone (=2H‐pyran‐2‐one) derivatives, rhodanthpyrones A and B (1 and 2, resp.), together with fourteen known compounds, 3–16, were isolated from the whole plants of Gentiana rhodantha. ...The structures of these compounds were elucidated by spectroscopic analyses. This is the first report on the occurrence of α‐pyrone derivatives in the genus Gentiana.
A multicomponent cyclocondensation of 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one with 4-amino-5-hydrazino-4H-1,2,4triazol-3-thiol and acetyl acetone/EAA or ...ethyl-2-(2-arylhydrazono)-3-oxobutanoates is described for the synthesis of pyrazolyl-1,2,4triazolo3,4-b1,3,4thiadiazin-6-yl)-2H-pyran-2-one derivatives and evaluated for their antimicrobial activity.
A series of simple or/and aryl, heteryl hydrazono pyrazolyl-1,2,4triazolo3,4-b1,3,4thiadiazin-6-yl)-2H-pyran-2-one derivatives have been efficiently synthesized in excellent yields via one-pot, multi-component approach. The importance of this methodology is that in a one-pot operation four new bonds (3C–N and 1C–S) are generated. The structure of compound 5a was confirmed by single-crystal X-ray diffraction. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against gram-positive bacteria (Staphylococcusaureus and Bacillussubtilis), gram-negative bacteria (Escherichiacoli andKlebsiellapneumoniae), antifungal activity against Candida albicans, and nematicidal activity against Meloidogyneincognita. Among all the compounds 6f showed excellent antimicrobial and nematicidal activity against tested bacteria, fungi, and nematodes.
With the application of a double dienophile 1,1'-(hexane-1,6-diyl)bis(1H-pyrrole-2,5-dione) for a 4+2 cycloaddition with a substituted 2H-pyran-2-one a novel 26-membered tetraaza heteromacrocyclic ...system 3 was prepared via a direct method under solvent-free conditions with microwave irradiation. The macrocycle prepared is composed of two units of the dienophile and two of the diene. The structure of the macrocycle was characterized on the basis of IR, 1H and 13C NMR and mass spectroscopy, as well as by the elemental analysis and melting point determination. With X-ray diffraction of a single crystal of the macrocycle we have determined that the two acetyl groups (attached to the bridging double bond of the bicyclo2.2.2octene fragments) are oriented towards each other (and also towards the inside of the cavity of the macrocycle), therefore, mostly filling it completely.
Two new tricyclic sesterterpenes, fusaprolifins A and B (1 and 2), and three new 2H‐pyran‐2‐one derivatives, prolipyrones A – C (3–5), were isolated and characterized from Fusarium proliferatum ...MA‐84, an endophytic fungus obtained from the fresh tissue of the marine mangrove plant Bruguiera sexangula. In addition, two known sesterterpenes, terpestacin (6) and fusaproliferin (7), and one known 2H‐pyran‐2‐one derivative, gibepyrone D (8), were also identified. The structures of these compounds were elucidated by detailed spectroscopic analyses. Fusaprolifin A (1) showed moderate activity against brine shrimp (Artemia salina), with a lethality rate of 49.5% at 100 μg/ml, while fusaprolifin B (2) showed weak activity.
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