The hitherto unknown bis[quinazolin-4-one-2-yl]-m-phenylene (2d), and its 3-N-substituted derivatives were prepared from the corresponding bis[3,1-benzoxazin-4-one-2-yl]-m-phenylene (1) as precursor. The quinazolinone derivative 2d was converted into bis[quinazolin-4-thioxo-2-yl]-m-phenylene (3) via different routes, bis[4-chloroquinazolin-2-yl]-m-phenylene (8) and bis[4-hydrazinoquinazolin-2-y...

Nikulin has classified all finite abelian groups acting symplectically on a K3 surface and he has shown that the induced action on the K3 lattice U⊕E8(−1) depends only on the group but not on the K3 surface. For all the groups in the list of Nikulin we compute the invariant sublattice and its orthogonal complement by using some special elliptic K3 surfaces.

Two independent mol-ecules comprise the crystallographic asymmetric unit in the title anti-retroviral agent Efavirenz, C(14)H(9)ClF(3)NO(2), and these have noteworthy differences in conformation. The major difference relates to the orientation of the 2-cyclo-propyl-ethynyl residue relative to the six-membered heterocycle: this approaches an orthogonal disposition in mol-ecule a compared to a mo...

In the crystal structure of the title compound, C(22)H(19)N(3)O(3), inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into a zigzag chain parallel to the face diagonal of the ac plane. The meth-oxy phenyl rings make a dihdral angle of 32.38 (7)° and form dihedral angles of 0.66 (8) and 24.17 (7)° with the fused benzooxazine ring system.

In the title compound, C14H8N4O6, the benzoxazin-4-one fused-ring system (r.m.s. deviation = 0.018 Å) is coplanar with the attached benzene ring [dihedral angle = 0.81 (4)°], there being an intra-molecular N-H⋯N hydrogen bond between them. Each nitro group is twisted out of the plane of the attached benzene ring [O-N-C-C torsion angles = 167.94 (11) and 170.38 (11)°]. In the crystal, amine-nitr...