Copper(I) complexes of a new participative triphosphane ligand (2H) have been prepared and structurally characterized: in particular, [Cu(2H)I] [Cu(2)]2. Hydrogenation the latter species afforded trimetallic hydride [Cu3(2)2(μ-H)] or, presence BEt3, [Cu(2H)(HBEt3)]. Their formation evidences transient [Cu(2H)H] formed by hydrogenolysis Cu–N bond [Cu(2H)(HBEt3)] behaves like complex inserts CO2 ...

Efficient kinetic resolution of racemic 3-nitro-2H-chromenes by bifunctional thiourea afforded optically active (R)-3-nitro-2H-chromene derivatives with moderate to good enantioselectivities, which simultaneously gave the multifunctional 3,4-diphenyl-3a-nitrobenzopyrano-[3,4-c]-pyrrolidine-1,1-dicarboxylate derivatives with four vicinal chiral carbon centers.

In the title chromenone derivative, C(10)H(8)O(2), the two fused six-membered rings are coplanar, with a mean deviation of 0.0261 (1) Å from the plane through the non-H atoms of the rings. The carbonyl and methyl substituents of the pyran ring also lie close to that plane, with the O and C atoms deviating by 0.0557 (1) and 0.1405 (1) Å, respectively. In the crystal, weak C-H⋯O contacts form cha...

In the title compound, C(19)H(16)O(4), there are two 4-hy-droxy-benzyl substituents on the oxan-4-one (tetra-hydro-pyran-4-one) ring, which exhibits an envelope conformation. The dihedral angles between pyran-one ring and the two benzene rings are 26.69 (9) and 36.01 (9)° while the benzene rings make a dihedral angle of 20.88 (10)°. In the crystal, mol-ecules are linked by inter-molecular O-H⋯O...

The second total synthesis of Brevisamide, a marine cyclic ether alkaloid from Karenia brevis, is reported. This streamlined synthesis proceeds in 21 steps, 14 steps longest linear sequence, in 5.2% overall yield and features a key SmI(2) reductive cyclization step to access the tetrasubstituted pyran core.

In the title compound, C10H5ClO3, a chlorinated 3-formyl-chromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0456 Å) with the largest deviation from the least-squares plane [0.1136 (16) Å] being found for the ring-bound carbonyl O atom. In the crystal, mol-ecules are linked through stacking inter-actions along the b axis [shortest centroid-centroid distance betwe...

In the xanthene ring system of the title compound, C(23)H(25)BrO(4), the 4H-pyran ring is almost planar [maximum deviation = 0.040 (3) Å] and the cyclo-hexene ring adopts a sofa conformation. The cyclo-hexene ring attached to the xanthene system is puckered [Q(T) = 0.427 (3) Å, θ = 55.0 (4) ° and ϕ = 164.4 (6) °]. In the crystal, mol-ecules are linked to each other by O-H⋯O and C-H⋯O hydrogen b...

The asymmetric unit of the title compound, C(29)H(29)ClO(11), contains two independent mol-ecules of similar geometry, both adopting an E conformation about the C=C double bond. The dihedral angles formed by benzene rings are 10.73 (16) and 13.79 (18)°. The pyran-oside rings adopt a chair conformation. Intra-molecular C-H⋯O close contacts occur. The crystal packing is stabilized by inter-molecu...

In the mol-ecular structure of the title compound, C(25)H(21)NO(4), the pyran ring adopts a flattened boat conformation, while the cyclo-hexenone ring is in an envelope conformation. The 4-nitro-phenyl ring is almost perpendicular to the pyran ring [dihedral angle = 89.39 (1)°]. In the crystal, mol-ecules are connected by inter-molecular C-H⋯O hydrogen bonds.