Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and Implications for their Cyclization Reactions.
Clark, Andrew J.; Curran, Dennis P.; Fox, David J.; Ghelfi, Franco; Guy, Collette S.; Hay, Benjamin; James, Natalie; Phillips, Jessica M.; Roncaglia, Fabrizio; Sellars, Philip B.; Wilson, Paul; Zhang, Hanmo; The Journal of organic chemistry 81 (2016) 5547–5565; doi:10.1021/acs.joc.6b00889

data_4036906
_publ_section_title
;
 Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and
 Implications for their Cyclization Reactions.
;
_journal_issue                   13
_journal_name_full               'The Journal of organic chemistry'
_journal_page_first              5547
_journal_page_last               5565
_journal_paper_doi               10.1021/acs.joc.6b00889
_journal_volume                  81
_journal_year                    2016
_chemical_formula_moiety         'C20 H21 N O'
_chemical_formula_sum            'C20 H21 N O'
_chemical_formula_weight         291.38
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_date             2016-04-21
_audit_creation_method
;
Olex2 1.2
(compiled 2016.02.16 svn.r3265 for OlexSys, GUI svn.r5155)
;
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.3684(3)
_cell_length_b                   9.7503(4)
_cell_length_c                   22.0856(9)
_cell_measurement_reflns_used    3157
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      32.54
_cell_measurement_theta_min      3.31
_cell_volume                     1586.72(11)
_computing_cell_refinement       'CrysAlis RED, Oxford Diffraction Ltd'
_computing_data_collection       'CrysAlis CCD, Oxford Diffraction Ltd'
_computing_data_reduction        'CrysAlis RED, Oxford Diffraction Ltd'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXH-1997 (Sheldrick, 2008)'
_computing_structure_solution    'ShelXS-1997 (Sheldrick, 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_detector_area_resol_mean 10.2833
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.933
_diffrn_measurement_device_type  'Oxford Diffraction Gemini R'
_diffrn_measurement_method       '\f & \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0361
_diffrn_reflns_av_unetI/netI     0.0751
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       23
_diffrn_reflns_limit_l_min       -33
_diffrn_reflns_number            8310
_diffrn_reflns_theta_full        29.00
_diffrn_reflns_theta_max         32.60
_diffrn_reflns_theta_min         3.32
_diffrn_source                   'fine-focus sealed tube'
_exptl_absorpt_coefficient_mu    0.074
_exptl_absorpt_correction_T_max  1.00
_exptl_absorpt_correction_T_min  0.75
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'ABSPACK(CrysAlis, Oxford Diffraction)'
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.220
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.3
_exptl_crystal_size_mid          0.1
_exptl_crystal_size_min          0.1
_refine_diff_density_max         0.372
_refine_diff_density_min         -0.237
_refine_diff_density_rms         0.053
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.916
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     201
_refine_ls_number_reflns         4726
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.916
_refine_ls_R_factor_all          0.0767
_refine_ls_R_factor_gt           0.0548
_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^)+(0.0624P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1112
_refine_ls_wR_factor_ref         0.1169
_reflns_number_gt                3401
_reflns_number_total             4726
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo6b00889_si_002.cif
_cod_data_source_block           pw4
_cod_original_cell_volume        1586.74(11)
_cod_database_code               4036906
_olex2_refinement_description
;
weakly diffracting crystals recorded with Mo radiation so Flack parameter (-1.7(19)) 
unreliable but absolute structure not required as not a chiral synthesis.

1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Secondary CH2 refined with riding coordinates:
 C3(H3A,H3B), C4(H4A,H4B), C15(H15A,H15B)
2.b Aromatic/amide H refined with riding coordinates:
 C6(H6), C7(H7), C8(H8), C9(H9), C17(H17), C18(H18), C19(H19), C20(H20),
 C21(H21)
2.c Idealised Me refined as rotating group:
 C1(H1A,H1B,H1C), C14(H14A,H14B,H14C)
;
_olex2_submission_special_instructions 'No special instructions were received'
_shelx_res_checksum              15578