Synthesis of type II beta-turn surrogate dipeptides based on syn-alpha-amino-alpha,beta-dialkyl-beta-lactams.
Palomo, Claudio; Aizpurua, Jesus M.; Ganboa, Iñaki; Benito, Ana; Cuerdo, Lourdes; Fratila, Raluca M.; Jimenez, Azucena; Loinaz, Iraida; Miranda, José I; Pytlewska, Kinga R.; Micle, Andreea; Linden, Anthony; Organic letters 6 (2004) 4443–4446; doi:10.1021/ol048348c

data_1506987
_publ_section_title
;
 Synthesis of type II beta-turn surrogate dipeptides based on
 syn-alpha-amino-alpha,beta-dialkyl-beta-lactams.
;
_journal_issue                   24
_journal_name_full               'Organic letters'
_journal_page_first              4443
_journal_page_last               4446
_journal_paper_doi               10.1021/ol048348c
_journal_volume                  6
_journal_year                    2004
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C40 H50 N2 O3 Si2'
_chemical_formula_sum            'C40 H50 N2 O3 Si2'
_chemical_formula_weight         663.01
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      19
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_date             03-11-19
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   13.4279(2)
_cell_length_b                   16.4550(2)
_cell_length_c                   17.0828(2)
_cell_measurement_reflns_used    6080
_cell_measurement_temperature    160(1)
_cell_measurement_theta_max      30.0
_cell_measurement_theta_min      2.0
_cell_volume                     3774.55(8)
_computing_cell_refinement       'DENZO-SMN (Otwinowski & Minor, 1997)'
_computing_data_collection       'COLLECT (Nonius, 2000)'
_computing_data_reduction
'DENZO-SMN and SCALEPACK (Otwinowski & Minor, 1997)'
_computing_molecular_graphics    'ORTEPII (Johnson, 1976)'
_computing_publication_material  'SHELXL97 and PLATON (Spek, 2003)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR92 (Altomare et al., 1994)'
_diffrn_ambient_temperature      160(1)
_diffrn_detector                 '65 mm CCD camera on \k goniostat'
_diffrn_detector_area_resol_mean 9
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Nonius KappaCCD area-detector diffractometer'
_diffrn_measurement_method       '\f and \w scans with \k offsets'
_diffrn_radiation_monochromator  'horizontally mounted graphite crystal'
_diffrn_radiation_source         'Nonius FR590 sealed tube generator'
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0620
_diffrn_reflns_av_sigmaI/netI    0.0603
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       23
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       -23
_diffrn_reflns_number            79602
_diffrn_reflns_theta_full        30.02
_diffrn_reflns_theta_max         30.02
_diffrn_reflns_theta_min         2.48
_diffrn_standards_decay_%        0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.132
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.167
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             1424
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.23
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.251
_refine_diff_density_min         -0.234
_refine_diff_density_rms         0.040
_refine_ls_abs_structure_details 'Flack & Bernardinelli (1999; 2000)'
_refine_ls_abs_structure_Flack   0.07(7)
_refine_ls_extinction_coef       0.0059(6)
_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   1.014
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     434
_refine_ls_number_reflns         11024
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.014
_refine_ls_R_factor_all          0.0721
_refine_ls_R_factor_gt           0.0419
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0461P)^2^+0.1576P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0858
_refine_ls_wR_factor_ref         0.0978
_reflns_number_gt                8107
_reflns_number_total             11032
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ol048348csi20040901_035745.cif
_cod_data_source_block           28
_cod_original_sg_symbol_H-M      'P 21 21 21   '
_cod_database_code               1506987