NHC-mediated enantioselective formal [4 + 2] cycloadditions of alkylarylketenes and β,γ-unsaturated α-ketocarboxylic esters and amides.
Leckie, Stuart M.; Brown, T. Bruce; Pryde, David; Lebl, Tomas; Slawin, Alexandra M. Z.; Smith, Andrew D.; Organic & biomolecular chemistry 11 (2013) 3230–3246; doi:10.1039/c3ob40424b

data_7152918
_publ_section_title
;
 NHC-mediated enantioselective formal [4 + 2] cycloadditions of
 alkylarylketenes and \b,\g-unsaturated \a-ketocarboxylic esters and
 amides.
;
_journal_issue                   19
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              3230
_journal_page_last               3246
_journal_paper_doi               10.1039/c3ob40424b
_journal_volume                  11
_journal_year                    2013
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C22 H22 O4'
_chemical_formula_sum            'C22 H22 O4'
_chemical_formula_weight         350.41
_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
_cell_angle_alpha                90.0000
_cell_angle_beta                 98.901(14)
_cell_angle_gamma                90.0000
_cell_formula_units_Z            2
_cell_length_a                   12.174(6)
_cell_length_b                   6.293(3)
_cell_length_c                   12.398(6)
_cell_measurement_reflns_used    1092
_cell_measurement_temperature    173
_cell_measurement_theta_max      68.25
_cell_measurement_theta_min      21.35
_cell_volume                     938.4(8)
_computing_cell_refinement       'CrystalClear-SM Expert 2.0 r2'
_computing_data_collection       'CrystalClear-SM Expert 2.0 r2 (Rigaku, 2009)'
_computing_data_reduction        'CrystalClear-SM Expert 2.0 r2'
_computing_molecular_graphics    'CrystalStructure 4.0'
_computing_publication_material  'CrystalStructure 4.0 (Rigaku, 2010)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SIR2004 (Burla, et al., 2005)'
_diffrn_ambient_temperature      173
_diffrn_detector_area_resol_mean 29.257
_diffrn_measured_fraction_theta_full 0.933
_diffrn_measured_fraction_theta_max 0.924
_diffrn_measurement_device_type  'Rigaku Saturn70'
_diffrn_measurement_method       \w
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54187
_diffrn_reflns_av_R_equivalents  0.0642
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            9926
_diffrn_reflns_theta_full        67.00
_diffrn_reflns_theta_max         68.52
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.685
_exptl_absorpt_correction_T_max  0.966
_exptl_absorpt_correction_T_min  0.688
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'REQAB (Rigaku, 1998)'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.240
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             372.00
_exptl_crystal_size_max          0.200
_exptl_crystal_size_mid          0.100
_exptl_crystal_size_min          0.050
_refine_diff_density_max         0.290
_refine_diff_density_min         -0.190
_refine_ls_abs_structure_details
'Flack, H. D. (1983), Acta Cryst. A39, 876-881. 1387 Friedel Pairs'
_refine_ls_abs_structure_Flack   0.1(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.065
_refine_ls_hydrogen_treatment    constr
_refine_ls_number_parameters     235
_refine_ls_number_reflns         3143
_refine_ls_number_restraints     1
_refine_ls_R_factor_gt           0.0498
_refine_ls_shift/su_max          0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0690P)^2^+0.1844P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.1347
_reflns_number_gt                2932
_reflns_number_total             3143
_reflns_threshold_expression     F^2^>2.0\s(F^2^)
_cod_data_source_file            c3ob40424b.txt
_cod_data_source_block           8
_cod_original_cell_volume        938.3(8)
_cod_database_code               7152918