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  • 1
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structure of 4,17a-di(2-hydroxyethyl)-4,17a-diaza-d-homo-5α-androstane, C22N2O2H40 (HS461), the tertiary amine related to HS781, a potential bisquaternary neuromuscular blocking agent, has been determined by direct methods and refined by full-matrix least squares toR=0.0867 for 2049 reflections (R=0.0597), CuKα radiation θ≦65°. The space group is P212121 a=20.295(4),b=7.278(6),c=14.052(4) Å,Z=4. The rings in the modified steroid nucleus are alltrans connected symmetrical chairs. Hydroxyethyl side groups at N(4) and N(17a) both have an equatorial disposition, and the side chains assumetrans conformations.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structure of the potent synthetic aza steroidal neuromuscular blocking agent 17aβ-(2-hydroxyethyl)-3β-pyrrolidino-17a-aza-D-homo-5-androstene dimethiodide (HS-626), (C27H48N2O)2+2I−, has been determined by the heavy-atom method and refined by block diagonal least squares toR o =0.044 for 3041 observed reflections andR=0.072 for 4313 reflections measured on a four-circle diffractometer in the ω/2θ scanning mode, employing Nb-filtered MoKα radiation. The crystals are orthorhombic,P212121,a=14.671(2),b=17.594(3),c=10.908(2) Å,Z=4. RingsA, C, andD-homo have chair conformations, ringB is a half-chair, and the pyrrolidine ringE has an envelope conformation. The N+---N+ distance of 10.33 Å is within the usual range associated with potent neuromuscular blocking. The hydroxyethyl side group appended to N+ (17a) forms part of an acetylcholine-like moiety which is observed to adopt thet,-g conformation commonly found in acetylcholine. This feature probably accounts for the dramatic increase in potency of HS-626 compared to similar drugs lacking this feature. Potential-energy calculations for the free HS-626 molecule indicate that the side chain may adopt a variety of conformations in the ranget, (+ g to− g).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structures of two forms of 17β-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene (HS-625) are reported. In HS-625 (aqueous solvate) form 1, moleculeA, and HS-625 (anhydride) form 2, moleculeB, the pyrrolidine group is 3-β substituted, while in HS-625 (anhydride) form 2, moleculeC has its pyrrolidine ring α-substituted. HS-625 form 1 is orthorhombic, space groupP212121, witha=7.089(4),b=11.502(6),c=28.975(16) Å,Z=4; form 2 is triclinic, space groupP1, witha=14.013(8),b=12.572(6),c=6.688(4) Å, α=95.187(20), β=103.491(21); γ=86.210(20)°,Z=2. MoleculesA andB have similar geometry, differences in moleculeC being related to strain caused by the unusual 3-α ring substituent which also produces a pronounced kink in the backbone of the molecule. An unusual feature of the analysis of form 1 is the location of the water hydrogens in the difference electron density well above background. None of the OH hydrogens was located. Both structures are hydrogen bonded, but the pyrrolidine nitrogen N(31) in moleculeC is heavily congested and is unable to act as an acceptor. The hydroxyethyl side chain, important for activity, has a different conformation in the three molecules (t,g, t,-g, andt,t respectively).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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