The structure of buprenorphine hydrochloride {(6R,7R,14S)-17-cyclopropylmethyl-7,8-dihydro- 7-[(1S)-1-hydroxy-1,2,2-trimethylpropyl]- 6-O-methyl-6,14-ethano-17-normorphine hydrochloride} was solved by direct methods and refined anisotropically to the R value of 0.062 for 3 049 observed reflections. The substance crystallizes in the tetragonal space group P43212, a = b = 11.513(2) Å, c = 42.054(8) Å, V = 5 574(2) Å3, Z = 8, Dcalc = 1.201 g cm-3, μ(MoKα) = 0.17 mm-1. The compound is the first morphine derivative with a 6,14-ethano bridge whose molecular structure has been solved.

No abstract

The structures of O-acetyl-(4R)-4-(E-2-butyl)-4,N-dimethyl-L-threonyl-cyclosporin A (1) and O-acetyl-(4R)-4-[E-2-(4-bromobutyl)]-4,N-dimethyl-L-threonyl-cyclosporin A (2) were determined by X-ray diffraction methods and compared with the structure of related cyclosporins. In contrast to expectation, neither the acetylation nor the subsequent bromination of 1 affects the conformation and packing of cyclosporins in the solid state. Both compounds are isomorphous and crystallize in the orthorhombic space group P212121 with a = 12.936(2) Å, b = 15.590(2) Å, c = 36.280(3) Å, and a = 12.916(3) Å, b = 15.675(4) Å, c = 36.715(7) Å, for 1 and 2, respectively.

Source of material 4-(2',4'-Difluorobiphenyl-4-yl)-2-methylene-4-oxobutanoic acid (20 g) [1] was dissolved in acetic acid (100 ml), Pd/C was added (10 % Pd/C, 50 % H20,8 g), and the reaction mixture was hydrogenated at ambient pressure under vigorous stirring on magnetic stirrer and heating at 60 °C. After 5 h, Pd/C was filtered off and the solution was evaporated on rotary vacuum evaporator. Deoxoflobufen (4-(2' ,4' -difluorobiphenyl-4-yl)-2-methylbutanoic acid) was obtained by crystallization from methanol (yield 17.8 g/ 93 %). Single crystals were obtained by cooling of solution of deoxoflobufen (400 mg) in methanol (4 ml)/water (0.2 ml). Experimental detailsThe small and anisotropically shaped crystal combined with the low scattering power of the participating elements lead to a very small ratio of number of intensities greater that 2cr(/ 0 bs) to number of refined parameters. The hydrogen atoms were geometrically restrained to ride on idealized positions. Their displacement parameters were fixed on values resulted from a preceding refinement stage. DiscussionThe structure is related to flobufen [ 1,2], an anti-inflammatory a>-biphenyl-co-oxoalkanoic acid. The basic structural motif is created by pairs of deoxoflobufen molecules lying with their long axes nearly parallel in a head-to-head arrangement. Due to the presence of fluorine atoms, the aromatic C-C bonds are on average slightly shorter in the difluorophenyl ring. The dihedral angle of the phenyl rings is 49.0(2)° similarly as in related structures [2,3]. The crystal structure of deoxoflobufen is built up by the typical dimers via their carboxyl groups. The second molecule of the dimer is generated by the center of symmetry operation, D

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.