Modified chiral triazolium salts for enantioselective benzoin cyclization of enolizable keto-aldehydes: synthesis of (+)-sappanone B.
Takikawa, Hiroshi; Suzuki, Keisuke; Organic letters 9 (2007) 2713–2716; doi:10.1021/ol070929p

data_1505435
_publ_section_title
;
 Modified chiral triazolium salts for enantioselective benzoin cyclization
 of enolizable keto-aldehydes: synthesis of (+)-sappanone B.
;
_journal_issue                   14
_journal_name_full               'Organic letters'
_journal_page_first              2713
_journal_page_last               2716
_journal_paper_doi               10.1021/ol070929p
_journal_volume                  9
_journal_year                    2007
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C25 H21 Br O7'
_chemical_formula_sum            'C25 H21 Br O7'
_chemical_formula_weight         513.33
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_symmetry_Int_Tables_number      4
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.777(9)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   13.937(6)
_cell_length_b                   5.674(2)
_cell_length_c                   14.021(6)
_cell_measurement_reflns_used    6981
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      27.59
_cell_measurement_theta_min      1.45
_cell_volume                     1108.7(8)
_computing_cell_refinement       SAINT
_computing_data_collection       SMART
_computing_data_reduction        SAINT
_computing_molecular_graphics    'ORTEP-3 for Windows (Farrugia, 1998)'
_computing_publication_material  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 0.928
_diffrn_measured_fraction_theta_max 0.939
_diffrn_measurement_device_type  'Bruker SMART CCD area detector system'
_diffrn_measurement_method       '\w scan'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0913
_diffrn_reflns_av_sigmaI/netI    0.2008
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       18
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            6981
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         27.59
_diffrn_reflns_theta_min         1.45
_diffrn_source                   'rotating anode X-ray tube'
_exptl_absorpt_coefficient_mu    1.899
_exptl_absorpt_correction_T_max  0.9279
_exptl_absorpt_correction_T_min  0.6585
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.538
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             524
_exptl_crystal_size_max          0.24
_exptl_crystal_size_mid          0.04
_exptl_crystal_size_min          0.04
_refine_diff_density_max         0.460
_refine_diff_density_min         -1.268
_refine_diff_density_rms         0.100
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.010(17)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.839
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     300
_refine_ls_number_reflns         4149
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.839
_refine_ls_R_factor_all          0.1348
_refine_ls_R_factor_gt           0.0613
_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^)+(0.0576P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1344
_refine_ls_wR_factor_ref         0.1540
_reflns_number_gt                1969
_reflns_number_total             4149
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol070929psi20070420_024007.cif
_cod_data_source_block           takigawa
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               1505435