Base-promoted [4 + 2] cycloaddition of <i>para</i>-quinone methides (<i>p</i>-QMs) and 3-cyanochromones: facile access to chromeno[2,3-<i>b</i>]chromenes.
Qiao, Qiwei; Sun, Hong; Sudprasert, Pirada; Cheng, Jin; Organic & biomolecular chemistry 23 (2025) 10669–10673; doi:10.1039/d5ob01516b

data_7160849
_publ_section_title
;
 Base-promoted [4 + 2] cycloaddition of <i>para</i>-quinone methides
 (<i>p</i>-QMs) and 3-cyanochromones: facile access to
 chromeno[2,3-<i>b</i>]chromenes.
;
_journal_issue                   47
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              10669
_journal_page_last               10673
_journal_paper_doi               10.1039/d5ob01516b
_journal_volume                  23
_journal_year                    2025
_chemical_formula_sum            'C31 H31 N O4'
_chemical_formula_weight         481.57
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2025-09-22 deposited with the CCDC.	2025-11-11 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   9.3834(5)
_cell_length_b                   16.1469(9)
_cell_length_c                   17.4024(10)
_cell_measurement_reflns_used    8690
_cell_measurement_temperature    193(2)
_cell_measurement_theta_max      53.84
_cell_measurement_theta_min      4.74
_cell_volume                     2636.7(3)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2014)'
_diffrn_ambient_temperature      193(2)
_diffrn_measured_fraction_theta_full 0.992
_diffrn_measured_fraction_theta_max 0.991
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           GaK\a
_diffrn_radiation_wavelength     1.34139
_diffrn_reflns_av_R_equivalents  0.0336
_diffrn_reflns_av_unetI/netI     0.0339
_diffrn_reflns_Laue_measured_fraction_full 0.992
_diffrn_reflns_Laue_measured_fraction_max 0.991
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       19
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            14428
_diffrn_reflns_point_group_measured_fraction_full 0.941
_diffrn_reflns_point_group_measured_fraction_max 0.937
_diffrn_reflns_theta_full        53.594
_diffrn_reflns_theta_max         53.865
_diffrn_reflns_theta_min         4.742
_exptl_absorpt_coefficient_mu    0.405
_exptl_absorpt_correction_type   none
_exptl_crystal_density_diffrn    1.213
_exptl_crystal_description       block
_exptl_crystal_F_000             1024
_refine_diff_density_max         0.140
_refine_diff_density_min         -0.153
_refine_diff_density_rms         0.029
_refine_ls_abs_structure_details
;
 Flack x determined using 1759 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.13(11)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.101
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     330
_refine_ls_number_reflns         4538
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.101
_refine_ls_R_factor_all          0.0390
_refine_ls_R_factor_gt           0.0343
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0500P)^2^+0.2035P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0883
_refine_ls_wR_factor_ref         0.0915
_reflns_Friedel_coverage         0.826
_reflns_Friedel_fraction_full    0.886
_reflns_Friedel_fraction_max     0.880
_reflns_number_gt                4155
_reflns_number_total             4538
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5ob01516b2.cif
_cod_data_source_block           S_a
_cod_depositor_comments          'Adding full bibliography for 7160849.cif.'
_cod_database_code               7160849
_shelx_shelxl_version_number     2018/3
_shelx_res_checksum              76860