A biomimetic strategy to access the silybins: total synthesis of (-)-isosilybin a.
McDonald, Benjamin R.; Nibbs, Antoinette E.; Scheidt, Karl A.; Organic letters 17 (2015) 98–101; doi:10.1021/ol503303w

data_1518466
_publ_section_title
;
 A biomimetic strategy to access the silybins: total synthesis of
 (-)-isosilybin a.
;
_journal_issue                   1
_journal_name_full               'Organic letters'
_journal_page_first              98
_journal_page_last               101
_journal_paper_doi               10.1021/ol503303w
_journal_volume                  17
_journal_year                    2015
_chemical_formula_moiety         '0.5(C49 H53.04 O14)'
_chemical_formula_sum            'C24.5 H26.52 O7'
_chemical_formula_weight         432.97
_chemical_name_systematic
;
 ?
;
_space_group_crystal_system      monoclinic
_space_group_IT_number           5
_space_group_name_Hall           'C 2y'
_space_group_name_H-M_alt        'C 1 2 1'
_symmetry_space_group_name_Hall  'C 2y'
_symmetry_space_group_name_H-M   'C 1 2 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_audit_creation_date             2014-09-13
_audit_creation_method
;
Olex2 1.2
(compiled 2014.08.28 svn.r2986 for OlexSys, GUI svn.r4874)
;
_cell_angle_alpha                90
_cell_angle_beta                 95.331(7)
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   43.491(4)
_cell_length_b                   5.5109(5)
_cell_length_c                   18.3225(15)
_cell_measurement_reflns_used    5345
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      58.39
_cell_measurement_theta_min      4.08
_cell_volume                     4372.4(7)
_computing_cell_refinement       'SAINT V7.23A (Bruker, 2005)'
_computing_data_collection       'APEX2 V2.1-4 (Bruker, 2007)'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2008)'
_computing_structure_solution    'ShelXS (Sheldrick, 2008)'
_diffrn_ambient_temperature      100.09
_diffrn_detector_area_resol_mean 8
_diffrn_measured_fraction_theta_full 0.982
_diffrn_measured_fraction_theta_max 0.982
_diffrn_measurement_device_type  'Bruker Kappa APEX CCD area detector'
_diffrn_measurement_method       '\w and \f scans'
_diffrn_radiation_monochromator  'Quazar optics'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0690
_diffrn_reflns_av_unetI/netI     0.0674
_diffrn_reflns_Laue_measured_fraction_full 0.982
_diffrn_reflns_Laue_measured_fraction_max 0.982
_diffrn_reflns_limit_h_max       48
_diffrn_reflns_limit_h_min       -48
_diffrn_reflns_limit_k_max       5
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            19480
_diffrn_reflns_point_group_measured_fraction_full 0.914
_diffrn_reflns_point_group_measured_fraction_max 0.914
_diffrn_reflns_theta_full        58.931
_diffrn_reflns_theta_max         58.931
_diffrn_reflns_theta_min         2.040
_diffrn_source                   microsource
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.796
_exptl_absorpt_correction_T_max  0.7516
_exptl_absorpt_correction_T_min  0.5975
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2008/1 (Bruker,2008) was used for absorption correction.
wR2(int) was 0.0955 before and 0.0568 after correction.
The Ratio of minimum to maximum transmission is 0.7950.
The \l/2 correction factor is 0.0015.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.315
_exptl_crystal_description       plate
_exptl_crystal_F_000             1836
_exptl_crystal_size_max          0.629
_exptl_crystal_size_mid          0.163
_exptl_crystal_size_min          0.02
_refine_diff_density_max         0.890
_refine_diff_density_min         -0.380
_refine_diff_density_rms         0.112
_refine_ls_abs_structure_details
;
 Flack x determined using 1410 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons and Flack (2004), Acta Cryst. A60, s61).
;
_refine_ls_abs_structure_Flack   0.0(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.053
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     614
_refine_ls_number_reflns         5740
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.053
_refine_ls_R_factor_all          0.1121
_refine_ls_R_factor_gt           0.0768
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;
 w=1/[\s^2^(Fo^2^)+(0.1639P)^2^+1.4312P]
 where P=(Fo^2^+2Fc^2^)/3
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2036
_refine_ls_wR_factor_ref         0.2394
_reflns_Friedel_coverage         0.656
_reflns_Friedel_fraction_full    0.826
_reflns_Friedel_fraction_max     0.826
_reflns_number_gt                4182
_reflns_number_total             5740
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ol503303w_si_002.cif
_cod_data_source_block           n0698_0m
_cod_depositor_comments          'Adding full bibliography for 1518466.cif.'
_cod_original_formula_sum        'C24.50 H26.52 O7'
_cod_database_code               1518466
_shelxl_version_number           2012-9
_shelx_estimated_absorpt_t_max   0.984
_shelx_estimated_absorpt_t_min   0.635
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups, All O(H) groups
2. Others
 Sof(H11A)=Sof(C48)=Sof(H48A)=Sof(H48B)=Sof(C49)=Sof(H49)=Sof(C50)=Sof(H50)=
 Sof(C51)=Sof(H51A)=Sof(H51B)=1-FVAR(1)
 Sof(H11)=Sof(C43)=Sof(H43)=Sof(C44)=Sof(H44)=Sof(C46)=Sof(H46)=Sof(C47)=
 Sof(H47)=FVAR(1)
3.a Ternary CH refined with riding coordinates:
 C15(H15), C23(H23), C24(H24)
3.b Secondary CH2 refined with riding coordinates:
 C6(H6A,H6B), C18(H18A,H18B), C22(H22A,H22B), C41(H41A,H41B), C48(H48A,H48B),
 C51(H51A,H51B)
3.c Aromatic/amide H refined with riding coordinates:
 C1A(H1A), C1B(H1B), C4(H4), C8(H8), C10(H10), C11(H11), C11(H11A), C12(H12),
 C14(H14), C16(H16), C17(H17), C21(H21), C26(H26), C29(H29), C30(H30), C43(H43),
  C44(H44), C46(H46), C47(H47), C49(H49), C50(H50)
3.d Idealised Me refined as rotating group:
 C33(H33A,H33B,H33C), C34(H34A,H34B,H34C), C35(H35A,H35B,H35C), C38(H38A,H38B,
 H38C), C39(H39A,H39B,H39C), C40(H40A,H40B,H40C), C45(H45A,H45B,H45C)
3.e Idealised tetrahedral OH refined as rotating group:
 O1(H1), O5(H5)
;
_shelx_res_checksum              94076
_shelx_hkl_checksum              8071
_olex2_submission_special_instructions 'No special instructions were received'