Organocatalytic asymmetric synthesis of both cis- and trans-configured pyrano[2,3-b]chromenes via different dehydration pathways
Lv, Xue-Jiao; Zhao, Wei-Wei; Chen, Ying-Han; Wan, Sheng-Biao; Liu, Yan-Kai; Organic Chemistry Frontiers 6 (2019) 1972–; doi:10.1039/C9QO00366E

data_1554892
_publ_section_title
;
 Organocatalytic asymmetric synthesis of both cis- and trans-configured
 pyrano[2,3-b]chromenes via different dehydration pathways
;
_journal_issue                   12
_journal_name_full               'Organic Chemistry Frontiers'
_journal_page_first              1972
_journal_paper_doi               10.1039/C9QO00366E
_journal_volume                  6
_journal_year                    2019
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C20 H18 O4'
_chemical_formula_sum            'C20 H18 O4'
_chemical_formula_weight         322.34
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2019-01-26
_audit_creation_method
;
Olex2 1.2
(compiled 2018.05.29 svn.r3508 for OlexSys, GUI svn.r5506)
;
_audit_update_record
;
2019-02-02 deposited with the CCDC.	2019-04-19 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 116.926(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   10.3231(13)
_cell_length_b                   8.3376(10)
_cell_length_c                   10.6510(13)
_cell_measurement_reflns_used    2591
_cell_measurement_temperature    100.15
_cell_measurement_theta_max      27.451
_cell_measurement_theta_min      2.280
_cell_volume                     817.35(17)
_computing_cell_refinement       'SAINT v8.34A (Bruker, 2013)'
_computing_data_reduction        'SAINT v8.34A (Bruker, 2013)'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT (Sheldrick, 2015)'
_diffrn_ambient_temperature      100.15
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.984
_diffrn_measurement_device_type  'Bruker D8 Venture'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0125
_diffrn_reflns_av_unetI/netI     0.0231
_diffrn_reflns_Laue_measured_fraction_full 0.996
_diffrn_reflns_Laue_measured_fraction_max 0.984
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            4947
_diffrn_reflns_point_group_measured_fraction_full 0.949
_diffrn_reflns_point_group_measured_fraction_max 0.900
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.530
_diffrn_reflns_theta_min         3.251
_exptl_absorpt_coefficient_mu    0.091
_exptl_absorpt_correction_T_max  0.7456
_exptl_absorpt_correction_T_min  0.6878
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
'SADABS-2014/3 (Bruker,2014/3) was used for absorption correction. wR2(int) was 0.0726 before and 0.0293 after correction. The Ratio of minimum to maximum transmission is 0.9225. The \l/2 correction factor is 0.00150.'
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.310
_exptl_crystal_description       block
_exptl_crystal_F_000             340
_refine_diff_density_max         0.136
_refine_diff_density_min         -0.178
_refine_diff_density_rms         0.035
_refine_ls_abs_structure_details
;
 Flack x determined using 1155 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.2(4)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.048
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     218
_refine_ls_number_reflns         3389
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.048
_refine_ls_R_factor_all          0.0432
_refine_ls_R_factor_gt           0.0357
_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^)+(0.0446P)^2^+0.0950P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0852
_refine_ls_wR_factor_ref         0.0905
_reflns_Friedel_coverage         0.712
_reflns_Friedel_fraction_full    0.895
_reflns_Friedel_fraction_max     0.804
_reflns_number_gt                3014
_reflns_number_total             3389
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c9qo00366e2.cif
_cod_data_source_block           190122lxj_0m
_cod_database_code               1554892
_shelx_shelxl_version_number     2018/3
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C4(H4), C5(H5), C7(H7)
2.b Secondary CH2 refined with riding coordinates:
 C16(H16A,H16B)
2.c Aromatic/amide H refined with riding coordinates:
 C8(H8), C9(H9), C10(H10), C12(H12), C13(H13), C14(H14), C15(H15), C17(H17),
 C18(H18), C19(H19)
2.d Idealised Me refined as rotating group:
 C20(H20A,H20B,H20C)
;
_shelx_res_checksum              63046
_shelx_hkl_checksum              40406
_olex2_submission_special_instructions 'No special instructions were received'