Synthesis and Conformational Properties of 3,4-Difluoro-l-prolines.
Hofman, Gert-Jan; Ottoy, Emile; Light, Mark E.; Kieffer, Bruno; Martins, Jose C.; Kuprov, Ilya; Sinnaeve, Davy; Linclau, Bruno; The Journal of organic chemistry 84 (2019) 3100–3120; doi:10.1021/acs.joc.8b02920

data_4033905
_publ_section_title
;
 Synthesis and Conformational Properties of 3,4-Difluoro-l-prolines.
;
_journal_issue                   6
_journal_name_full               'The Journal of organic chemistry'
_journal_page_first              3100
_journal_page_last               3120
_journal_paper_doi               10.1021/acs.joc.8b02920
_journal_volume                  84
_journal_year                    2019
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C17 H21 F2 N O4'
_chemical_formula_sum            'C17 H21 F2 N O4'
_chemical_formula_weight         341.35
_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     dual
_audit_creation_date             2018-03-07
_audit_creation_method
;
Olex2 1.2-alpha
(compiled 2018.02.02 svn.r3481 for OlexSys, GUI svn.r5470)
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.8181(5)
_cell_length_b                   10.3879(6)
_cell_length_c                   18.1295(10)
_cell_measurement_reflns_used    12083
_cell_measurement_temperature    120(2)
_cell_measurement_theta_max      71.760
_cell_measurement_theta_min      4.879
_cell_volume                     1660.69(16)
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT (Sheldrick, 2015)'
_diffrn_ambient_temperature      120(2)
_diffrn_detector                 'Image Plate'
_diffrn_detector_type            'Rigaku IP'
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.983
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'Rigaku R-AXIS SPIDER IP'
_diffrn_measurement_method       '\w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54187
_diffrn_reflns_av_R_equivalents  0.0636
_diffrn_reflns_av_unetI/netI     0.0463
_diffrn_reflns_Laue_measured_fraction_full 0.997
_diffrn_reflns_Laue_measured_fraction_max 0.983
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            12083
_diffrn_reflns_point_group_measured_fraction_full 0.995
_diffrn_reflns_point_group_measured_fraction_max 0.971
_diffrn_reflns_theta_full        67.687
_diffrn_reflns_theta_max         71.760
_diffrn_reflns_theta_min         4.879
_diffrn_source                   'sealed X-ray tube'
_diffrn_source_target            Cu
_exptl_absorpt_coefficient_mu    0.946
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.6606
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'ABSCOR; Higashi, 1995'
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.365
_exptl_crystal_description       block
_exptl_crystal_F_000             720
_exptl_crystal_recrystallization_method
'The material was recrystallised from DCM by slow evaporation'
_exptl_crystal_size_max          0.42
_exptl_crystal_size_mid          0.32
_exptl_crystal_size_min          0.1
_refine_diff_density_max         0.206
_refine_diff_density_min         -0.157
_refine_diff_density_rms         0.039
_refine_ls_abs_structure_details
;
 Flack x determined using 1195 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.08(7)
_refine_ls_extinction_coef       0.0043(5)
_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   1.034
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     221
_refine_ls_number_reflns         3144
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.034
_refine_ls_R_factor_all          0.0321
_refine_ls_R_factor_gt           0.0302
_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^)+(0.0232P)^2^+0.3521P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0721
_refine_ls_wR_factor_ref         0.0733
_reflns_Friedel_coverage         0.711
_reflns_Friedel_fraction_full    0.993
_reflns_Friedel_fraction_max     0.954
_reflns_number_gt                2999
_reflns_number_total             3144
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            jo8b02920_si_004.cif
_cod_data_source_block           2018sot0003_s1_120k
_cod_database_code               4033905
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_max   0.911
_shelx_estimated_absorpt_t_min   0.692
_olex2_refinement_description
;
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 Ternary CH refined with riding coordinates:
 C2(H2), C3(H3), C4(H4)
2.b Secondary CH2 refined with riding coordinates:
 C1(H1A,H1B), C11(H11A,H11B)
2.c Aromatic/amide H refined with riding coordinates:
 C13(H13), C14(H14), C15(H15), C16(H16), C17(H17)
2.d Idealised Me refined as rotating group:
 C7(H7A,H7B,H7C), C8(H8A,H8B,H8C), C9(H9A,H9B,H9C)
;
_shelx_res_checksum              63144
_shelx_hkl_checksum              93959
_olex2_date_sample_submission    2018-02-12
_olex2_diffrn_ambient_temperature_device 'Oxford Cryosystems'
_olex2_exptl_crystal_mounting_method
'The crystal was mounted on a MITIGEN holder with silicon oil'
_olex2_submission_original_sample_id GJH-8259-99
_olex2_submission_special_instructions 'No special instructions were received'