Comparative Study of the Synthesis and Structural and Physicochemical Properties of Diketopiperazines vs Aza-diketopiperazines.
Regenass, Pierre; Bosc, Damien; Riché, Stéphanie; Gizzi, Patrick; Hibert, Marcel; Karmazin, Lydia; Ganesan, A.; Bonnet, Dominique; The Journal of organic chemistry  (2017) –; doi:10.1021/acs.joc.6b02895

data_4032374
_publ_section_title
;
 Comparative Study of the Synthesis and Structural and Physicochemical
 Properties of Diketopiperazines vs Aza-diketopiperazines.
;
_journal_name_full               'The Journal of organic chemistry'
_journal_paper_doi               10.1021/acs.joc.6b02895
_journal_year                    2017
_chemical_absolute_configuration rm
_chemical_formula_moiety         'C15 H20 N2 O2'
_chemical_formula_sum            'C15 H20 N2 O2'
_chemical_formula_weight         260.33
_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'
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2013
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.4252(3)
_cell_length_b                   9.1913(4)
_cell_length_c                   17.9879(6)
_cell_measurement_reflns_used    5808
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      27.485
_cell_measurement_theta_min      0.998
_cell_volume                     1392.96(9)
_computing_cell_refinement       'Denzo (Nonius B.V., 1998)'
_computing_data_collection       'Collect (Nonius B.V., 1998)'
_computing_data_reduction        'Denzo (Nonius B.V., 1998)'
_computing_molecular_graphics    'PLATON 98 (Spek, 1998)'
_computing_publication_material  'SHELXL-2013 (Sheldrick, 2013)'
_computing_structure_refinement  'SHELXL-2013 (Sheldrick, 2013)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  KappaCCD
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0612
_diffrn_reflns_av_unetI/netI     0.0518
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 0.999
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -23
_diffrn_reflns_number            9773
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.999
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.488
_diffrn_reflns_theta_min         2.264
_diffrn_source                   'fine-focus sealed tube'
_exptl_absorpt_coefficient_mu    0.083
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.241
_exptl_crystal_description       prism
_exptl_crystal_F_000             560
_exptl_crystal_size_max          0.38
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.30
_refine_diff_density_max         0.180
_refine_diff_density_min         -0.218
_refine_diff_density_rms         0.051
_refine_ls_abs_structure_details
;
 Flack x determined using 951 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons and Flack (2004), Acta Cryst. A60, s61).
;
_refine_ls_abs_structure_Flack   -1.4(9)
_refine_ls_extinction_coef       0.031(4)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.043
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     179
_refine_ls_number_reflns         3179
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.043
_refine_ls_R_factor_all          0.0566
_refine_ls_R_factor_gt           0.0410
_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^)+(0.0434P)^2^+0.1039P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0881
_refine_ls_wR_factor_ref         0.0946
_reflns_Friedel_coverage         0.731
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     0.999
_reflns_number_gt                2642
_reflns_number_total             3179
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            jo6b02895_si_003.cif
_cod_data_source_block           mhpr130912
_cod_database_code               4032374
_shelxl_version_number           2013-4
_shelx_res_checksum              15163
_shelx_hkl_checksum              20828