Chiral Lewis acid catalyzed asymmetric cycloadditions of disubstituted ketenes for the synthesis of β-lactones and δ-lactones.
Hao, Xiaoyu; Liu, Xiaohua; Li, Wei; Tan, Fei; Chu, Yangyang; Zhao, Xiaohu; Lin, Lili; Feng, Xiaoming; Organic letters 16 (2014) 134–137; doi:10.1021/ol4031217

data_1513509
_publ_section_title
;
 Chiral Lewis acid catalyzed asymmetric cycloadditions of disubstituted
 ketenes for the synthesis of \b-lactones and \d-lactones.
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_journal_issue                   1
_journal_name_full               'Organic letters'
_journal_page_first              134
_journal_page_last               137
_journal_paper_doi               10.1021/ol4031217
_journal_volume                  16
_journal_year                    2014
_chemical_absolute_configuration ad
_chemical_formula_sum            'C21 H19 Br O4'
_chemical_formula_weight         415.27
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_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                 96.817(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   11.5559(16)
_cell_length_b                   6.3280(9)
_cell_length_c                   13.4204(18)
_cell_measurement_reflns_used    2121
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      44.704
_cell_measurement_theta_min      6.115
_cell_volume                     974.4(2)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SHELXTL'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'CCD area detector'
_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     0.71073
_diffrn_reflns_av_R_equivalents  0.0374
_diffrn_reflns_av_sigmaI/netI    0.0703
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            5842
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         26.00
_diffrn_reflns_theta_min         1.77
_exptl_absorpt_coefficient_mu    2.131
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.0893
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            green
_exptl_crystal_density_diffrn    1.415
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prismatic
_exptl_crystal_F_000             424
_exptl_crystal_size_max          0.211
_exptl_crystal_size_mid          0.154
_exptl_crystal_size_min          0.113
_refine_diff_density_max         0.518
_refine_diff_density_min         -0.494
_refine_diff_density_rms         0.054
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.005(13)
_refine_ls_extinction_coef       0.012(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.059
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     238
_refine_ls_number_reflns         3448
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.058
_refine_ls_R_factor_all          0.0596
_refine_ls_R_factor_gt           0.0473
_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^)+(0.0646P)^2^+0.0569P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1255
_refine_ls_wR_factor_ref         0.1317
_reflns_number_gt                2733
_reflns_number_total             3448
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol4031217_si_003.cif
_cod_data_source_block           cd213302
_cod_depositor_comments
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The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to
/usr/data/users/saulius/automatic-downloads/current/ACS/lib/dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 2281 2013-09-26 08:29:07Z andrius 
;
_cod_original_sg_symbol_H-M      P2(1)
_cod_database_code               1513509