Diverging Pathways to Topologically Complex Polycyclic Bis-acetals and Their Ring System Interchange.
Castillo, Rafael R.; Aquino, Maurizio; Gandara, Zoila; Safir, Imad; Elkhayat, Zobida; Retailleau, Pascal; Arseniyadis, Siméon; Organic letters 14 (2012) 1628–1631; doi:10.1021/ol300388b

data_1507195
_publ_section_title
;
 Diverging Pathways to Topologically Complex Polycyclic Bis-acetals and
 Their Ring System Interchange.
;
_journal_issue                   6
_journal_name_full               'Organic letters'
_journal_page_first              1628
_journal_page_last               1631
_journal_paper_doi               10.1021/ol300388b
_journal_volume                  14
_journal_year                    2012
_chemical_formula_moiety         'C18 H20 O4'
_chemical_formula_sum            'C18 H20 O4'
_chemical_formula_weight         300.34
_chemical_name_systematic
; 
 rac-(4aR,8aR,9R)-11-methoxy-5,6,7,8,9,13b-hexahydro-1H-
1,9-epoxy-3,8a-methanoanthra[4a,10-d][1,3]dioxin 
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 97.189(5)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   9.031(2)
_cell_length_b                   13.795(5)
_cell_length_c                   11.711(4)
_cell_measurement_reflns_used    3458
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      27.88
_cell_measurement_theta_min      1.00
_cell_volume                     1447.5(8)
_computing_cell_refinement
'DENZO (Otwinowski & Minor, 1997); COLLECT (Nonius B.V., 1999)'
_computing_data_collection
'DENZO (Otwinowski & Minor, 1997); COLLECT (Nonius B.V., 1999)'
_computing_data_reduction        'SCALEPACK (Otwinowski & Minor, 1997)'
_computing_molecular_graphics    'PLATON (Spek, 2003)'
_computing_publication_material  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_refinement
'SHELXL97 (Sheldrick, 2008); CRYSTALBUILDER (Welter, 2006)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Nonius kappa-CCD diffractometer'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.0247
_diffrn_reflns_av_sigmaI/netI    0.0417
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -18
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            13373
_diffrn_reflns_theta_full        27.88
_diffrn_reflns_theta_max         27.88
_diffrn_reflns_theta_min         2.29
_exptl_absorpt_coefficient_mu    0.097
_exptl_absorpt_correction_T_max  0.98
_exptl_absorpt_correction_T_min  0.89
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Scalepack (Otwinowski & Minor, 1997)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.378
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             640
_exptl_crystal_size_max          0.43
_exptl_crystal_size_mid          0.37
_exptl_crystal_size_min          0.19
_refine_diff_density_max         0.219
_refine_diff_density_min         -0.198
_refine_diff_density_rms         0.044
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.029
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     200
_refine_ls_number_reflns         3446
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.029
_refine_ls_R_factor_all          0.0853
_refine_ls_R_factor_gt           0.0482
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0649P)^2^+0.1785P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1126
_refine_ls_wR_factor_ref         0.1321
_reflns_number_gt                2245
_reflns_number_total             3446
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol300388b_si_003.cif
_cod_data_source_block           compound_3b
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               1507195