A new 2H-pyran-2-one derivative, 4-hydroxy-6-(4-methoxyphenethyl)-2H-pyran-2-one (
1
), together with four known compounds, 5,6-dehydrokawain (
2
), dihydro-5,6-dehydrokawain (
3
), ...(E)-labda-8(17),12-diene-15,16-dial (
4
), and quercetin (
5
) were isolated from the rhizomes of Alpinia zerumbet. (E)-Labda-8(17),12-diene-15,16-dial (
4
) and quercetin (
5
) exhibited potent inhibition, with IC
50
values of 3.18 ± 1.13 and 1.17 ± 0.13 μg/mL, respectively, against formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-induced superoxide anion (O
2
−
) generation.
An expeditious synthesis of several 2-amino-isophthalonitriles and their biaryl compounds is described and illustrated by carbanion-induced ring transformation of functionalized 2
H-pyran-2-ones with ...malononitrile in excellent yields. The strength of the reaction lies in the creation of an aromatic ring at room temperature from six-membered lactones under mild reaction conditions. This approach is an alternative to Diels–Alder reactions of 2
H-pyran-2-ones with dienophiles, which require forcing thermal conditions to obtain benzene derivatives.
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When grown on a non-penetretable at a surface angle of 45°, Arabidopsis roots form wave-like structures and, in wild type rarely, but in certain mutants the tip root even may form circles. These ...circles are called coils. The formation of coils depends on the complex interaction of circumnutation, gravitropism and negative thigmotropism where – at least – gravitropism is intimately linked to auxin transport and signaling. The knockout mutant of patatin-related phospholipase-AI-1 (pplaI-1) is an auxin-signaling mutant which forms moderately increased numbers of coils on tilted agar plates. We tested the effects of the auxin efflux transport inhibitor NPA (1-naphthylphtalamic acid) and of the influx transport inhibitor 1-NOA (1-naphthoxyacetic acid) which both further increased root coil formation. The pPLAI-1 inhibitors HELSS (haloenol lactone suicide substrate=E-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one) and ETYA (eicosatetraynoic acid) which are auxin signaling inhibitors also increased coil formation. In addition, far red light treatment increased coil formation. The results point out that a disturbance of auxin transport and signaling is one potential cause for root coils. As we show that the mutant pplaI-1 penetrates horizontal agar plates better than wild type plants root movements may help penetrating the soil.
Two new 2
H
-pyran-2-one glucosides, cuscutarosides A (
1
) and B (
2
), and one new steroidal glucoside, 7
β
-methoxy-
β
-sitosterol 3-
O
-
β
-glucopyranoside (
3
), together with 12 known compounds ...(
4
–
15
) were isolated from the whole plant of
Cuscuta reflexa
(Convolvulaceae) collected from Myanmar. The chemical structures of these new compounds were elucidated based on extensive spectroscopic analysis. The antiobesity activity of these isolates was evaluated using porcine pancreatic lipase (PPL), and the antiplatelet aggregation activity was screened using rabbit platelets induced by thrombin, platelet-activating factor (PAF), arachidonate (AA), or collagen. 7
β
-Methoxy-
β
-sitosterol 3-
O
-
β
-glucopyranoside (
3
) showed weak PPL inhibitory activity. Cuscutaroside A (
1
), its acetylated derivative (
1a
), and scrophenoside B (
8
) showed weak inhibitory activity against rabbit platelet aggregation induced by collagen. Compound
1a
also showed inhibitory activity against rabbit platelet aggregation induced by AA.
Graphic Abstract
A direct one-pot base-induced alkenylation of indolin-2-ones has been developed by using 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles. Different bases such as MeONa, NaH and t-BuONa have been ...used to optimize the reaction conditions to obtain the desired product. NaH in THF was found to be the most suitable for the alkenylation of indolin-2-ones. Reaction in the presence of other bases led to the formation of 1-aryl-3-methoxy/methylthio-5H-dibenzod,f1,3diazepin-6(7H)-ones. Quantum chemical calculations have been performed to explain the nature of the weak noncovalent interactions operating in the supramolecular architectures of alkenylated indoline-2-ones and to explain the relative stability of one of the tautomers with respect to the others.
A convenient green procedure have been proposed for the synthesis of 6-(2-arylvinyl)-4-hydroxy-3-(phenylsulfanyl)-2
H
-pyran-2-ones by condensation of 6-(arylvinyl)-4-hydroxy-2
H
-pyran-2-ones with ...S-phenyl benzenesulfonothioate in aqueous potassium hydroxide at room temperature.
A general, highly efficient synthesis of arylated benzenes from simple stitching of α-oxo-ketene-
S,S-acetals and functionalized deoxybenzoins via a ‘lactone intermediate’ is described. This ...procedure offers easy access to highly functionalized arylated benzenes containing sterically demanding groups in good to excellent yields. The advantage of the procedure lies in the fabrication of arylated benzenes with desired conformational flexibility along the molecular axis at room temperature and in a transition metal-free environment through easily accessible precursors.
A practical stereoselective synthesis of (6S)-5,6,dihydro-6-(2R)-2-hydroxy-6-phenyl hexyl-2H-pyran-2-one, a potent natural antifungal compound, is described. The sequence involves diastereoselective ...iodine-induced electrophilic cyclization, epoxide ring opening with a vinyl Grignard reagent and ring closing metathesis (RCM) as the key steps.
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