The title compound, C(26)H(37)NO(5), was the reaction product of hellebrigenin with N,N-dimethyl-formamide. It consists of three cyclo-hexane rings (A, B and C), one five-membered ring (D) and one dihydro-pyran ring (E). The stereochemistry of the ring junctions is is A/B cis, B/C trans, C/D cis and C/E trans. The cyclo-hexane rings A, B and C have chair conformations. Both the five-membered ri...

In the title compound, C19H14FN3O3, the central pyran ring adopts a boat conformation with the O atom and the quaternary C atom diagonally opposite displaced by 0.068 (1) and 0.075 (1) Å, respectively, above the mean plane defined by the other four ring atoms. The co-planar atoms of the pyran ring and the fluoro-phenyl ring are nearly perpendicular, as evidenced by the dihedral angle of 87.11 (...

In the title compound, C19H18FNO3S, the five-membered oxazolidine ring adopts an envelope conformation with the methine C atom of the fused bond as the flap. Its mean plane is oriented at a dihedral angle of 50.38 (1)° with respect to the fluoro-phenyl ring. The six-membered thio-pyran ring has a half-chair conformation and its mean plane is almost coplanar with the fused benzene ring, making a...

The mol-ecular structure of the title compound, C(19)H(20)O(2), reveals a slightly distorted chair conformation for the tetra-hydro-pyran ring with the two methyl and two phenyl substituents in equatorial positions.

In the title compound, C(18)H(20)O(4), both the tetra-hydro-pyran-one ring and the cyclo-hexene ring adopt envelope conformations. The crystal packing is stabilized by weak inter-molecular C-H⋯O hydrogen bonding.

Tandem reactions of cis-2-acyl-1-alkynyl-1-aryl cyclopropanes tuned by gold(i) and silver(i) catalysts are described, which afford selectively the key pyran-fused indene cores and the 2,4,6-trisubstituted phenols in good yields, respectively.

In the title compound, C(14)H(20)O(9), the six-membered pyran and the five-membered dioxalane rings adopt chair and twisted conformations, respectively. In the crystal, the mol-ecules are linked by C-H⋯O inter-actions.

Five new pyran rings containing polyketides, penicipyrans A-E (1-5), together with the known pestapyrone A (6), were isolated from the saline soil-derived Penicillium raistrickii. Their structures were determined by interpretation of NMR and HRESIMS data. The absolute configurations of compounds 4 and 5 were established by the modified Mosher's method and single-crystal X-ray diffraction analys...

Pyran copolymer enhances resistance to infections and transplantable tumors in mice. It induces interferon, activates macro phages, increases antibody-dependent cellular cytotoxicity (ADCC), functions as an adjuvant, and has direct antitumor effects. MVE-2, a low-molecular-weight (15,000) component of pyran copolymer, exhibited less toxicity and essentially the same positive biological effects ...

The new a-pyrone derivative II was isolated in crystalline form from extracts of dormant seeds of Rosa canina. It inhibits germination of seeds of Amaranthus caudatus completely, but reversibly, at conc. > 2.5 x 10~5 m . Its chemical structure was elucidated by mass spectrometry, 'Hand 13CNMR spectroscopy to be 3-methyl-l-oxa-bicyclo (4,1,0) hept-5-en-2-one-4,6-dicarboxylic acid di­ methylester...