Cinchona Alkaloid Squaramide Catalyzed Enantioselective Hydrazination/Cyclization Cascade Reaction of α-Isocyanoacetates and Azodicarboxylates: Synthesis of Optically Active 1,2,4-Triazolines
Mei-Xin Zhao; Hong-Lei Bi; Hao Zhou; Hui Yang; Min Shi; Journal of Organic Chemistry 78 (2013) 9377–9382; doi:10.1021/jo401585v

data_4028623
_publ_section_title
;
 Cinchona Alkaloid Squaramide Catalyzed Enantioselective
 Hydrazination/Cyclization Cascade Reaction of \a-Isocyanoacetates and
 Azodicarboxylates: Synthesis of Optically Active 1,2,4-Triazolines
;
_journal_name_full               'Journal of Organic Chemistry'
_journal_page_first              9377
_journal_page_last               9382
_journal_paper_doi               10.1021/jo401585v
_journal_volume                  78
_journal_year                    2013
_chemical_absolute_configuration ad
_chemical_formula_sum            'C20 H26 Br N3 O6'
_chemical_formula_weight         484.35
_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                 90.119(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   6.0255(3)
_cell_length_b                   16.0531(9)
_cell_length_c                   11.7146(6)
_cell_measurement_temperature    173(2)
_cell_volume                     1133.13(10)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_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  0.0284
_diffrn_reflns_av_sigmaI/netI    0.0445
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       -19
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            13069
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         2.15
_exptl_absorpt_coefficient_mu    1.853
_exptl_absorpt_correction_T_max  0.7814
_exptl_absorpt_correction_T_min  0.5551
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.420
_exptl_crystal_description       block
_exptl_crystal_F_000             500
_exptl_crystal_size_max          0.36
_exptl_crystal_size_mid          0.16
_exptl_crystal_size_min          0.14
_refine_diff_density_max         1.223
_refine_diff_density_min         -0.463
_refine_diff_density_rms         0.077
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.004(15)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.051
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     271
_refine_ls_number_reflns         3935
_refine_ls_number_restraints     14
_refine_ls_restrained_S_all      1.070
_refine_ls_R_factor_all          0.0671
_refine_ls_R_factor_gt           0.0577
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0818P)^2^+1.7526P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1520
_refine_ls_wR_factor_ref         0.1613
_reflns_number_gt                3414
_reflns_number_total             3935
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo401585v_si_002.cif
_cod_data_source_block           z
_cod_database_code               4028623