نتایج جستجو برای: 4h pyran
تعداد نتایج: 7801 فیلتر نتایج به سال:
The asymmetric unit of the title compound, C(25)H(22)OS, comprises two similar 4-(4-methoxy-phen-yl)-4-methyl-2,6-diphenyl-4H-thio-pyran mol-ecules. In each, the six-membered thio-pyran ring adopts a planar conformation (r.m.s. deviation of 0.041Å for the ring in one mol-ecule and 0.008 Å in the other). The methoxy-phenyl substituent is in a pseudo-axial position. The crystal studied is an inve...
‘Unconventional’ Coordination Chemistry by Metal Chelating Fragments in a Metalloprotein Active Site
The binding of three closely related chelators: 5-hydroxy-2-methyl-4H-pyran-4-thione (allothiomaltol, ATM), 3-hydroxy-2-methyl-4H-pyran-4-thione (thiomaltol, TM), and 3-hydroxy-4H-pyran-4-thione (thiopyromeconic acid, TPMA) to the active site of human carbonic anhydrase II (hCAII) has been investigated. Two of these ligands display a monodentate mode of coordination to the active site Zn(2+) io...
greater than the response of similarly treated blanks at the 5-gg level and 400 times greater than the response of methanol to flame ionization detection (1 ,5 ) . The compound in which the methanol is to be determined, must be somewhat water soluble. Complete dissolution of the sample weight taken in the 1-ml water-urea mixture used is necessary to free the methanol for subsequent reaction. Ac...
We designed a ceria-vanadia/silica (Ce-V/SiO2) heterogeneous catalyst and used it for the green and efficient synthesis of 2-amino-3-cyano-4H-pyran derivatives. The green reaction was a multicomponent one-pot condensation of 5,5-dimethylcyclohexane-1,3-dione, aromatic aldehyde, and malononitrile in an eco-compatible solvent (ethanol). The catalyst was synthesized and fully characterized by powd...
The 4H-pyran ring of the title compound, C(17)H(16)N(2)O(2), is nearly planar [maximum deviation = 0.077 (2) Å] and the cyclo-hexene ring adopts a flattened chair conformation [puckering parameters: Q(T) = 0.435 (2) Å, θ = 122.0 (3)° and ϕ = 53.5 (3)°]. The 4H-pyran ring is almost perpendicular to the benzene ring [dihedral angle = 87.23 (8)°] and is almost coplanar with the mean plane of the c...
In the title compound, C(18)H(17)ClN(2)O(2)·C(3)H(6)O, the 4H-pyran ring is nearly planar [maximum deviation = -0.108 (1) Å] and the cyclo-hexene ring is puckered [puckering parameters Q(T) = 0.4596 (17) Å, θ = 55.9 (2)° and ϕ = 226.5 (3)°]. The 4H-pyran ring is approximately perpendicular to the benzene ring [dihedral angle = 84.35 (7)°] and is almost coplanar with the mean plane of the cyclo-...
the three components one pot synthesis of 2-amino-4h-benzo-[b] -pyran derivatives were obtained in good to excellent yields within short reaction time by condensing dimedone, aldehydes and malanonitrile or ethylcyanoacetate using a catalytic amount of (diacetoxyiodo)benzene as hypervalent iodine in aqueous ethanol under reflux conditions have been discussed. this aqua mediated knoevenagel-cyclo...
synthesis of 4-(n,n- dimethylamino)-3-aryl-3-butene-2-one, ethyl-5-aryl-4-oxo-4h-pyran-2-carboxylate, ethyl-5-aryl-4-pyridones-2-carboxylate and 5-aryl-3-cyano-5-methyl-2-pyridones (aryl=3-thienyl, 2-furyl) are described.
Water is a versatile solvent in many ways, and in this sense performing organic reactions in this medium is now of great interest. The one-pot reaction of ethyl acetoacetate or benzyl acetoacetate, with benzaldehydes and malononitrile to provide some novel 6-amino-4-aryl-5-cyano-2-methyl-4H-pyran-3-carboxylates has been performed over nano MgO with high performance in water as a green solvent a...
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