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...

Phelligridin G is an unusual natural product that contains an embedded spiro-fused furanone core. We have investigated two furan-based synthetic approaches towards the spirocyclic core structure of this natural product from readily available 2-phenylfurans. Although initial studies involving an oxidative cyclization were unsuccessful, we were ultimately able to access this key system through ...

A chiral cooperative catalysis of NHC and Brønsted acid for a formal [4+2] reaction of unprotected isatins and enals was developed for the direct synthesis of unprotected spiro[indoline-3,2'-pyran]-2,6'(3'H)-diones in good to excellent yields (up to 95%) with high enantioselectivities (up to >93% ee).

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.