Highly enantioselective cyclizations of conjugated trienes with low catalyst loadings: a robust chiral N-heterocyclic carbene enabled by acetic Acid cocatalyst.
Liu, Guansai; Wilkerson, Phillip D.; Toth, Christopher A.; Xu, Hao; Organic letters 14 (2012) 858–861; doi:10.1021/ol203375y

data_1503601
_publ_section_title
;
 Highly enantioselective cyclizations of conjugated trienes with low
 catalyst loadings: a robust chiral N-heterocyclic carbene enabled by
 acetic Acid cocatalyst.
;
_journal_issue                   3
_journal_name_full               'Organic letters'
_journal_page_first              858
_journal_page_last               861
_journal_paper_doi               10.1021/ol203375y
_journal_volume                  14
_journal_year                    2012
_chemical_absolute_configuration ad
_chemical_formula_sum            'C21 H17 Cl O3'
_chemical_formula_weight         352.80
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   5.9241(6)
_cell_length_b                   15.5212(15)
_cell_length_c                   18.2461(17)
_cell_measurement_reflns_used    9198
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      28.7
_cell_measurement_theta_min      2.59
_cell_volume                     1677.7(3)
_computing_cell_refinement       'SAINT 7.46A (Bruker-AXS, 2009)'
_computing_data_collection       'APEX2 v2009.3.0 (Bruker-AXS, 2009)'
_computing_data_reduction        'SAINT 7.46A (Bruker-AXS, 2009)'
_computing_molecular_graphics    'Bruker SHELXTL (Sheldrick, 2008)'
_computing_publication_material  'Bruker SHELXTL (Sheldrick, 2008)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type
;
Bruker D8 goniometer with CCD area detector  
;
_diffrn_measurement_method       'omega and phi 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  0.0287
_diffrn_reflns_av_sigmaI/netI    0.0143
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       20
_diffrn_reflns_limit_k_min       -20
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       -24
_diffrn_reflns_number            37398
_diffrn_reflns_theta_full        28.68
_diffrn_reflns_theta_max         28.68
_diffrn_reflns_theta_min         1.72
_exptl_absorpt_coefficient_mu    0.245
_exptl_absorpt_correction_T_max  0.9642
_exptl_absorpt_correction_T_min  0.9435
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.397
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             736
_exptl_crystal_size_max          0.24
_exptl_crystal_size_mid          0.18
_exptl_crystal_size_min          0.15
_refine_diff_density_max         0.271
_refine_diff_density_min         -0.203
_refine_diff_density_rms         0.040
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.00(4)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.042
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     227
_refine_ls_number_reflns         4316
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.042
_refine_ls_R_factor_all          0.0277
_refine_ls_R_factor_gt           0.0268
_refine_ls_shift/su_max          0.002
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0421P)^2^+0.3962P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0719
_refine_ls_wR_factor_ref         0.0726
_reflns_number_gt                4202
_reflns_number_total             4316
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol203375y_si_001.cif
_cod_data_source_block           GSL-compound-54b
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 
;
_cod_original_sg_symbol_Hall     P2ac2ab
_cod_original_sg_symbol_H-M      P2(1)2(1)2(1)
_cod_database_code               1503601
_refine_ls_abs_structure_hooft   -0.011(11)