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_7151826
_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_absolute_configuration rm
_chemical_compound_source        synthesis
_chemical_formula_moiety         'C60 H105 N9 O12, 0.25(C2 H6 O), 1.5(H2 O)'
_chemical_formula_sum            'C60.5 H109.5 N9 O13.75'
_chemical_formula_weight         1183.1
_chemical_name_systematic
;
Boc-(Leu-Leu-Acp)3-OMe
;
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_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-97
_cell_angle_alpha                90.00
_cell_angle_beta                 96.234(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   15.4487(14)
_cell_length_b                   44.175(4)
_cell_length_c                   21.6774(19)
_cell_measurement_reflns_used    7403
_cell_measurement_temperature    240(2)
_cell_measurement_theta_max      23.05
_cell_measurement_theta_min      2.24
_cell_volume                     14706(2)
_computing_cell_refinement       'SMART (Bruker, 1998)'
_computing_data_collection       'SMART (Bruker, 1998)'
_computing_data_reduction        'SAINTPLUS (Bruker, 1998)'
_computing_molecular_graphics    'PLATON (Spek, 2001)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXD (Seldrick & Gould, 1996)'
_diffrn_ambient_temperature      240(2)
_diffrn_detector_area_resol_mean 8.366
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker AXS SMART APEX (CCD area detector)'
_diffrn_measurement_method       \w-scan
_diffrn_radiation_monochromator
'Bruker AXS Montel (conforcal multilayer optics)'
_diffrn_radiation_source         'MacScience M18XCE (rotating anode)'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0484
_diffrn_reflns_av_sigmaI/netI    0.0447
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       53
_diffrn_reflns_limit_k_min       -53
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -26
_diffrn_reflns_number            117361
_diffrn_reflns_theta_full        25.68
_diffrn_reflns_theta_max         25.68
_diffrn_reflns_theta_min         1.05
_diffrn_standards_decay_%        1.9
_diffrn_standards_interval_count 117361
_diffrn_standards_interval_time  780
_diffrn_standards_number         590
_exptl_absorpt_coefficient_mu    0.075
_exptl_absorpt_correction_T_max  1.0
_exptl_absorpt_correction_T_min  0.7178
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   'SADABS (Sheldrick, 1996)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.069
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             5164
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.05
_refine_diff_density_max         1.445
_refine_diff_density_min         -0.493
_refine_diff_density_rms         0.095
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -2.1(12)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.096
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           fullcycle
_refine_ls_number_parameters     3054
_refine_ls_number_reflns         28263
_refine_ls_number_restraints     2027
_refine_ls_restrained_S_all      1.152
_refine_ls_R_factor_all          0.1191
_refine_ls_R_factor_gt           0.0962
_refine_ls_shift/su_max          0.008
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1659P)^2^+11.7623P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2635
_refine_ls_wR_factor_ref         0.2857
_reflns_number_gt                21523
_reflns_number_total             28263
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            c0ob01146k.txt
_cod_data_source_block           llac1
_cod_original_sg_symbol_H-M      P21
_cod_database_code               7151826