Conformational studies on peptides containing α,α-disubstituted α-amino acids: chiral cyclic α,α-disubstituted α-amino acid as an α-helical inducer.
Demizu, Yosuke; Doi, Mitsunobu; Kurihara, Masaaki; Okuda, Haruhiro; Nagano, Masanobu; Suemune, Hiroshi; Tanaka, Masakazu; Organic & biomolecular chemistry 9 (2011) 3303–3312; doi:10.1039/c0ob01146k

data_7151823
_publ_section_title
;
 Conformational studies on peptides containing \a,\a-disubstituted
 \a-amino acids: chiral cyclic \a,\a-disubstituted \a-amino acid as an
 \a-helical inducer.
;
_journal_issue                   9
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              3303
_journal_page_last               3312
_journal_paper_doi               10.1039/c0ob01146k
_journal_volume                  9
_journal_year                    2011
_chemical_formula_sum            'C41 H68 N6 O9'
_chemical_formula_weight         789.01
_chemical_melting_point          196.0(10)
_chemical_name_systematic
;
Cbz-(Leu-Leu-Aib)2-OMe
;
_space_group_IT_number           1
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  'P 1'
_symmetry_space_group_name_H-M   'P 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                106.305(2)
_cell_angle_beta                 94.754(2)
_cell_angle_gamma                103.828(2)
_cell_formula_units_Z            1
_cell_length_a                   10.4109(5)
_cell_length_b                   11.0028(4)
_cell_length_c                   11.3302(5)
_cell_measurement_reflns_used    1539
_cell_measurement_temperature    302
_cell_measurement_theta_max      20.87
_cell_measurement_theta_min      2.29
_cell_volume                     1193.80(9)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      302
_diffrn_detector_area_resol_mean 8.333
_diffrn_measured_fraction_theta_full 0.977
_diffrn_measured_fraction_theta_max 0.977
_diffrn_measurement_device_type  'Bruker APEX2 CCD'
_diffrn_measurement_method       'phi and omega 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  0.0252
_diffrn_reflns_av_sigmaI/netI    0.0467
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            4615
_diffrn_reflns_theta_full        21.75
_diffrn_reflns_theta_max         21.75
_diffrn_reflns_theta_min         1.90
_exptl_absorpt_coefficient_mu    0.077
_exptl_absorpt_correction_T_max  0.9847
_exptl_absorpt_correction_T_min  0.9623
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   'SADABS sheldrick 1996'
_exptl_crystal_colour            clear
_exptl_crystal_density_diffrn    1.097
_exptl_crystal_density_meas      0
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             428
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.30
_exptl_crystal_size_min          0.20
_refine_diff_density_max         0.216
_refine_diff_density_min         -0.160
_refine_diff_density_rms         0.032
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.3(13)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.576
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     518
_refine_ls_number_reflns         3417
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.576
_refine_ls_R_factor_all          0.0534
_refine_ls_R_factor_gt           0.0434
_refine_ls_shift/su_max          0.005
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0870
_refine_ls_wR_factor_ref         0.0905
_reflns_number_gt                2950
_reflns_number_total             3417
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c0ob01146k.txt
_cod_data_source_block           a0507041dmz
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Triclinic' changed to 'triclinic'
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_enum 1555 2011-01-17 13:19:09Z saulius 

The following automatic conversions were performed:

'_chemical_melting_point' value '195-197' was changed to '196.0(10)'
- the average value was taken and precision was estimated.

Automatic conversion script
Id: cif_fix_values 1569 2011-02-09 13:29:24Z adriana 
;
_cod_original_sg_symbol_H-M      P1
_cod_database_code               7151823