Pregna-1,4,20-trien-3-one, a cytotoxic marine steroid from the marine soft coral <i>Nephthea</i> sp.
Tabot, Maria B.; Schnakenburg, Gregor; Gross, Harald; Acta Crystallographica Section E 66 (2010) o2040–o2041; doi:10.1107/S1600536810027352

data_2226882
_publ_section_title
;
 Pregna-1,4,20-trien-3-one, a cytotoxic marine steroid from the marine
 soft coral <i>Nephthea</i> sp.
;
_journal_coeditor_code           HB5516
_journal_issue                   8
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              o2040
_journal_page_last               o2041
_journal_paper_doi               10.1107/S1600536810027352
_journal_volume                  66
_journal_year                    2010
_chemical_formula_iupac          'C21 H28 O'
_chemical_formula_moiety         'C21 H28 O'
_chemical_formula_sum            'C21 H28 O'
_chemical_formula_weight         296.43
_chemical_name_common            Pregna-1,4,20-triene-3-one
_chemical_name_systematic
;(8<i>S</i>,9<i>S</i>,10<i>R</i>,13<i>R</i>,14<i>S</i>,17<i>R</i>)-10,13-
dimethyl-17-vinyl-6,7,8,9,10,11,12,13,14,15,16,17-dodecahydro-3<i>H</i>-
cyclopenta[<i>a</i>]phenanthren-3-one
;
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   6.967(5)
_cell_length_b                   11.470(9)
_cell_length_c                   20.891(16)
_cell_measurement_reflns_used    688
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      24.94
_cell_measurement_theta_min      2.64
_cell_volume                     1669(2)
_computing_cell_refinement       '<i>SAINT</i> (Bruker, 2009)'
_computing_data_collection       '<i>APEX2</i> (Bruker, 2009)'
_computing_data_reduction        '<i>SAINT</i> (Bruker, 2009)'
_computing_molecular_graphics    '<i>DIAMOND</i> (Brandenburg, 1999)'
_computing_publication_material  '<i>SHELXL97</i> (Sheldrick, 2008)'
_computing_structure_refinement  '<i>SHELXL97</i> (Sheldrick, 2008)'
_computing_structure_solution    '<i>SHELXS97</i> (Sheldrick, 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.977
_diffrn_measured_fraction_theta_max 0.977
_diffrn_measurement_device_type  'Bruker X8 Kappa APEXII'
_diffrn_measurement_method       'fine slicing \f and \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1419
_diffrn_reflns_av_sigmaI/netI    0.1741
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -24
_diffrn_reflns_number            7256
_diffrn_reflns_theta_full        28.00
_diffrn_reflns_theta_max         28.00
_diffrn_reflns_theta_min         2.64
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.070
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.179
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             648
_exptl_crystal_size_max          0.32
_exptl_crystal_size_mid          0.16
_exptl_crystal_size_min          0.06
_refine_diff_density_max         0.249
_refine_diff_density_min         -0.262
_refine_ls_extinction_coef       0.009(2)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     '<i>SHELXL97</i> (Sheldrick, 2008)'
_refine_ls_goodness_of_fit_ref   0.966
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     202
_refine_ls_number_reflns         2267
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.966
_refine_ls_R_factor_all          0.1596
_refine_ls_R_factor_gt           0.0627
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0414P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1112
_refine_ls_wR_factor_ref         0.1424
_reflns_number_gt                1144
_reflns_number_total             2267
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            hb5516.cif
_cod_data_source_block           I
_cod_database_code               2226882
_cod_database_fobs_code          2226882