Reversible Twisting of Primary Amides via Ground State N-C(O) Destabilization: Highly Twisted Rotationally-Inverted Acyclic Amides.
Meng, Guangrong; Shi, Shicheng; Lalancette, Roger A.; Szostak, Roman; Szostak, Michal; Journal of the American Chemical Society  (2017) –; doi:10.1021/jacs.7b11309

data_4126992
_publ_section_title
;
 Reversible Twisting of Primary Amides via Ground State N-C(O)
 Destabilization: Highly Twisted Rotationally-Inverted Acyclic Amides.
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_paper_doi               10.1021/jacs.7b11309
_journal_year                    2017
_chemical_absolute_configuration syn
_chemical_formula_moiety         'C18 H25 N O6'
_chemical_formula_sum            'C18 H25 N O6'
_chemical_formula_weight         351.39
_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'
_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-2014/7
_cell_angle_alpha                90.00(3)
_cell_angle_beta                 110.19(3)
_cell_angle_gamma                90.00(3)
_cell_formula_units_Z            2
_cell_length_a                   8.680(2)
_cell_length_b                   11.203(2)
_cell_length_c                   10.273(2)
_cell_measurement_reflns_used    8292
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      68.55
_cell_measurement_theta_min      3.95
_cell_volume                     937.6(4)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2014 (Sheldrick 2014)'
_computing_structure_solution    'SHELXS-97 (Sheldrick 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.981
_diffrn_measured_fraction_theta_max 0.967
_diffrn_measurement_device_type  'Bruker SMART CCD Apex-II area-detector'
_diffrn_measurement_method       '\f and \w'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0259
_diffrn_reflns_av_unetI/netI     0.0226
_diffrn_reflns_Laue_measured_fraction_full 0.981
_diffrn_reflns_Laue_measured_fraction_max 0.967
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            8510
_diffrn_reflns_point_group_measured_fraction_full 0.799
_diffrn_reflns_point_group_measured_fraction_max 0.786
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         68.550
_diffrn_reflns_theta_min         4.586
_exptl_absorpt_coefficient_mu    0.775
_exptl_absorpt_correction_T_max  0.902
_exptl_absorpt_correction_T_min  0.751
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details   'SADABS (Sheldrick, 2008a)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.245
_exptl_crystal_description       block
_exptl_crystal_F_000             376
_exptl_crystal_size_max          0.580
_exptl_crystal_size_mid          0.371
_exptl_crystal_size_min          0.209
_refine_diff_density_max         0.140
_refine_diff_density_min         -0.128
_refine_diff_density_rms         0.026
_refine_ls_abs_structure_details
;
 Flack x determined using 932 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.00(6)
_refine_ls_extinction_coef       0.0066(6)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2014/7 (Sheldrick 2014'
_refine_ls_goodness_of_fit_ref   1.050
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     234
_refine_ls_number_reflns         2718
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.050
_refine_ls_R_factor_all          0.0229
_refine_ls_R_factor_gt           0.0227
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0274P)^2^+0.1615P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0575
_refine_ls_wR_factor_ref         0.0576
_reflns_Friedel_coverage         0.540
_reflns_Friedel_fraction_full    0.595
_reflns_Friedel_fraction_max     0.583
_reflns_number_gt                2700
_reflns_number_total             2718
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja7b11309_si_003.cif
_cod_data_source_block           160510RAL_MENG_MeO_PH_DIBOC_100K_0m_a
_cod_database_code               4126992
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.662
_shelx_estimated_absorpt_t_max   0.855
_shelx_res_checksum              9141
_shelx_hkl_checksum              31732