Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions: Catalytic Enantioselective Oxa-Pictet-Spengler Reactions.
Zhao, Chenfei; Chen, Shawn B.; Seidel, Daniel; Journal of the American Chemical Society 138 (2016) 9053–9056; doi:10.1021/jacs.6b05225

data_4130617
_publ_section_title
;
 Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions:
 Catalytic Enantioselective Oxa-Pictet-Spengler Reactions.
;
_journal_issue                   29
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              9053
_journal_page_last               9056
_journal_paper_doi               10.1021/jacs.6b05225
_journal_volume                  138
_journal_year                    2016
_chemical_absolute_configuration ad
_chemical_formula_sum            'C17 H14 Br N O'
_chemical_formula_weight         328.20
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 91.2816(17)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   7.8217(7)
_cell_length_b                   6.0909(5)
_cell_length_c                   14.5030(12)
_cell_measurement_reflns_used    3749
_cell_measurement_temperature    150(2)
_cell_measurement_theta_max      29.62
_cell_measurement_theta_min      2.60
_cell_volume                     690.77(10)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXS-97 (Sheldrick 2008)'
_diffrn_ambient_temperature      150(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Bruker SMART APEX CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0227
_diffrn_reflns_av_unetI/netI     0.0367
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            7929
_diffrn_reflns_point_group_measured_fraction_full 0.998
_diffrn_reflns_point_group_measured_fraction_max 0.992
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.129
_diffrn_reflns_theta_min         1.404
_exptl_absorpt_coefficient_mu    2.970
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.5355
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details   'Bruker SAINT (SADABS)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.578
_exptl_crystal_description       plate
_exptl_crystal_F_000             332
_exptl_crystal_size_max          0.480
_exptl_crystal_size_mid          0.240
_exptl_crystal_size_min          0.010
_refine_diff_density_max         0.530
_refine_diff_density_min         -0.270
_refine_diff_density_rms         0.062
_refine_ls_abs_structure_details
; 
 Flack x determined using 1189 quotients [(I+)-(I-)]/[(I+)+(I-)] 
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259). 
;
_refine_ls_abs_structure_Flack   -0.001(8)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.199
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     181
_refine_ls_number_reflns         3693
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.199
_refine_ls_R_factor_all          0.0480
_refine_ls_R_factor_gt           0.0377
_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^)+(0.0300P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0715
_refine_ls_wR_factor_ref         0.0741
_reflns_Friedel_coverage         0.823
_reflns_Friedel_fraction_full    0.995
_reflns_Friedel_fraction_max     0.983
_reflns_number_gt                3154
_reflns_number_total             3693
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja6b05225_si_002.cif
_cod_data_source_block           cz-2030_P21
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               4130617
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.330
_shelx_estimated_absorpt_t_max   0.971
_exptl_absorpt_special_details
; 
 The faces used for the numerical absorption correction were 
FACE    1.00  0.00  0.00     0.120 
FACE   -1.00  0.00  0.00     0.120 
FACE    0.00  1.00  0.00     0.240 
FACE    0.00 -1.00  0.00     0.240 
FACE   -1.00  1.00  0.00     0.160 
FACE   -1.00 -1.00  0.00     0.140 
FACE    0.00  0.00  1.00     0.005 
FACE    0.00  0.00 -1.00     0.005 
;
_shelx_res_checksum              49446
_shelx_hkl_checksum              72088