12-Helix folding of cyclobutane beta-amino acid oligomers.
Fernandes, Carlos; Faure, Sophie; Pereira, Elisabeth; Théry, Vincent; Declerck, Valérie; Guillot, Régis; Aitken, David J.; Organic letters 12 (2010) 3606–3609; doi:10.1021/ol101267u

data_1503089
_publ_section_title
;
 12-Helix folding of cyclobutane beta-amino acid oligomers.
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_journal_issue                   16
_journal_name_full               'Organic letters'
_journal_page_first              3606
_journal_page_last               3609
_journal_paper_doi               10.1021/ol101267u
_journal_volume                  12
_journal_year                    2010
_chemical_absolute_configuration ad
_chemical_formula_moiety         '2(C46 H68 N8 O11), 3(C H Cl3)'
_chemical_formula_sum            'C95 H139 Cl9 N16 O22'
_chemical_formula_weight         2176.27
_space_group_IT_number           18
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      18
_symmetry_space_group_name_Hall  'P 2 2ab'
_symmetry_space_group_name_H-M   'P 21 21 2'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   21.4551(14)
_cell_length_b                   28.4412(19)
_cell_length_c                   8.9866(6)
_cell_measurement_reflns_used    9600
_cell_measurement_temperature    100(1)
_cell_measurement_theta_max      27.31
_cell_measurement_theta_min      2.35
_cell_volume                     5483.7(6)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      100(1)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0434
_diffrn_reflns_av_sigmaI/netI    0.0350
_diffrn_reflns_limit_h_max       29
_diffrn_reflns_limit_h_min       -29
_diffrn_reflns_limit_k_max       37
_diffrn_reflns_limit_k_min       -38
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            70127
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         28.78
_diffrn_reflns_theta_min         1.43
_diffrn_source                   'fine-focus sealed tube'
_diffrn_source_type              'kappa X8 APEX II Bruker ICMMO'
_exptl_absorpt_coefficient_mu    0.303
_exptl_absorpt_correction_T_max  0.988
_exptl_absorpt_correction_T_min  0.944
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.318
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             2300
_exptl_crystal_size_max          0.210
_exptl_crystal_size_mid          0.130
_exptl_crystal_size_min          0.030
_refine_diff_density_max         0.954
_refine_diff_density_min         -0.967
_refine_diff_density_rms         0.079
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.04(7)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     662
_refine_ls_number_reflns         14235
_refine_ls_number_restraints     10
_refine_ls_restrained_S_all      1.022
_refine_ls_R_factor_all          0.0789
_refine_ls_R_factor_gt           0.0637
_refine_ls_shift/su_max          0.003
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1042P)^2^+4.3454P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1682
_refine_ls_wR_factor_ref         0.1808
_reflns_number_gt                11885
_reflns_number_total             14235
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol101267u_si_002.cif
_cod_data_source_block           858GuillotICMMO
_cod_original_formula_sum        'C95 H139 Cl9 N16 O22 '
_cod_database_code               1503089