In the title compound, C10H6O4, also known as 3-carb-oxy-chromone, the non-H atoms of the chromone ring are essentially coplanar (r.m.s. deviation = 0.0057 Å), with the maximum deviation from their least-squares plane [0.011 (2) Å] being for a pyran C atom. The dihedral angle between the fused ring and plane of the carb-oxy group is 3.06 (2)°. An intra-molecular hydrogen bond is formed between ...

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.

The crystal structure of the title compound, C(30)H(38)N(2)O(5)Si, has been investigated to establish the relative stereochemistry at the spiro ring junction and the two anomeric centres. Each of the O atoms in the tetra-hydro-pyran rings adopts an axial position on the neighbouring ring. This bis--diaxial conformation is adopted, thus gaining maximum stablization from the anomeric effect. The ...

Tthe structure of the title compound, C(15)H(24)O(5), has been redetermined at 103 (2) K, with much improved precision. The title compound was first reported by Luo, Yeh, Brossi, Flippen-Anderson & Gillardi [Helv. Chim. Acta (1984). 67, 1515-1522]. It is a derivative of the anti-malaria compound artemisinin and consists primarily of three substituted ring systems fused together. A cyclo-hexane ...

The asymmetric unit of the title compound, C(17)H(14)O(6)S, contains four crystallographically independent mol-ecules in which the pyran-one units are essentially planar, with maximum deviations of 0.016 (2), 0.019 (2), 0.025 (2), 0.014 (2), 0.020 (2), 0.010 (2), 0.003 (2) and 0.012 (2) Å. One of the thio-phene rings is disordered over two positions, with an occupancy ratio of 0.739 (4):0.261 (...

In the title compound, C19H22N2O5, the six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation with the dimethyl-substituted C atom as the flap. The pyran ring has a flat-boat conformation. The meth-oxy-phenyl ring is orthogonal to the mean plane of the chromene moiety, with a dihedral angle of 89.97 (8)°. The amine N atom deviates from the chromene mean plane by 0....

In the title compound, C(23)H(23)NO(5)S·0.125H(2)O, the pyrrolidine ring has a twist conformation and the dihydro-pyran ring adopts a half-chair conformation; the two rings are cis-fused. The mol-ecule adopts a folded conformation. The sulfonyl-bound phenyl ring and the pyran ring of the coumarin ring system are stacked over one another, with a centroid-centroid distance of 3.7470 (7) Å; the di...

The synthesis and crystal structure of the title compound, C14H19NO8·H2O, prepared in three steps from 6-O-ethyl-1,2;3,4-di-O-iso-propyl-idene-α-d-galacto-pyran-ose using protecting-group strategies employed in carbohydrate chemistry, is reported. The asymmetric unit consists of a single galactoside mol-ecule, in which the pyran-oid ring has a 4C1 conformation and the 4-nitro-phenyl moiety is e...

An overview of the synthesis of the fungal metabolites (+)-dermolactone, (-)- semixanthomegnin, (+)- and (-)-mellein, (-)-ochratoxin alpha, (-)-(1R,3S)-thysanone, the enantiopure ventiloquinones L, E and G, and 8-desmethyleleutherin from a common chiral intermediate, is presented. Further methodology leading potentially toward extended quinones such as (3S,3'S)-xylindein is also outlined.