An operationally simple and efficient protocol for the construction of dihydrofuran derivatives has been accomplished via a sequential addition of N-chlorosuccinimide and a base to 2-amino-4H-pyran derivatives in alcohol medium. The one-pot protocol proceeding via tandem oxidative difunctionalization and ring contraction provides an entirely new strategy for the construction of the dihydrofuran...

The title compound, C(25)H(22)N(2)O(3), with three stereogenic centres, crystallizes in a centrosymmetric space group as a racemate. The pyran ring adopts a sofa conformation and the five-membered isoxazole ring exhibits an envelope conformation. The dihedral angle between the benzene ring and the mean plane through the near coplanar atoms of the pyran ring is 10.54 (9)°. In the crystal, no sig...

In the title compound, C(38)H(37)NO(3), the pyran ring has an envelope conformation with the quaternary C(q) atom as the flap atom. The dihedral angle formed between the meth-oxy-phenyl group and the naphthalene ring system is 67.32 (6)°. The ethyl-amino groups lie to the same side of the plane through the phenyl ring and form dihedral angles of 84.6 (3) and 75.8 (2)° with it.

In the title compound, C(17)H(17)FO(3), the benzene ring of the isochroman unit is inclined at 84.96 (7)° to the fluoro-benzene ring plane, and the pyran ring adopts a half-boat conformation. In the crystal structure, C-H⋯O hydrogen bonds link mol-ecules into rows along the c axis, while C-H⋯O inter-actions and C-H⋯F hydrogen bonds to the fluorine acceptor stack the mol-ecules down the b axis. ...

The title compound, C(13)H(13)NO(2)S, was prepared by a thermocyclization reaction from 3-methyl-6-(2-methyl-but-3-yn-2-yl-oxy)benzo[d]thia-zol-2(3H)-one. In the crystal structure, the methyl-thia-zole unit is planar, while the pyran ring assumes a screw-boat conformation. Intra-molecular C-H⋯O hydrogen bonding helps to stabilize the molecular structure.

In the title compound C(27)H(19)ClO(6), the coumarin ring system is not exactly planar, with a dihedral angle of 4.12 (7)° between its benzene and lactone rings. The cis-fused pyran rings adopt half-chair conformations. The carbometh-oxy and chloro-phenyl groups are in a trans configuration. The crystal packing is stabilized by inter-molecular C-H⋯O interactions, which produce a centrosymmetric...

In the title compound, C23H23NO8, the dihedral angle between the five- and six-membered rings of the indene-dione moiety is 3.09 (13)°. The mean plane of the five-membered ring (which has a flat envelope conformation with the spiro C atom as the flap) is inclined to the mean plane of the central five-membered ring of the pyrrolizine unit by 76.48 (12)°. This central ring has a twist conformatio...

In the title compound, C(24)H(22)ClNO(3), the dihedral angle between the naphthalene ring system and the chloro-phenyl ring is 67.44 (4)°. The pyrrolidine and dihydro-pyran rings exhibit envelope and half chair conformations, respectively. In the crystal structure, weak C-H⋯π inter-actions are observed.

In the title compound, C(27)H(24)N(2)O(3), the pyrroldine ring adopts a twist conformation, while the six-membered pyran-one ring of the coumarin ring system is in a sofa conformation. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion R(2) (2)(8) dimers. These dimers are further connected via C-H⋯O hydrogen bonds.

The asymmetric unit of the title compound, C26H28O6·2CH3OH, contains two independent methyl 6-O-trityl-α-d-gluco-pyran-oside mol-ecules and four methanol solvent mol-ecules. The rings of two methyl α-d-gluco-pyran-oside adopt chair conformations. In the crystal, extensive intra- and inter-molecular O-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular archi...