A base-promoted desalicyloylative dimerization of 3-(1-alkynyl)chromones: an unusual approach to 2-alkynyl xanthones.
Xie, Fuchun; Pan, Xuan; Lin, Shijun; Hu, Youhong; Organic & biomolecular chemistry 8 (2010) 1378–1381; doi:10.1039/b925234g

data_7153311
_publ_section_title
;
 A base-promoted desalicyloylative dimerization of 3-(1-alkynyl)chromones:
 an unusual approach to 2-alkynyl xanthones.
;
_journal_issue                   6
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              1378
_journal_page_last               1381
_journal_paper_doi               10.1039/b925234g
_journal_volume                  8
_journal_year                    2010
_chemical_formula_sum            'C26 H16 O4'
_chemical_formula_weight         392.39
_space_group_IT_number           61
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2ac 2ab'
_symmetry_space_group_name_H-M   'P b c a'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   14.460(2)
_cell_length_b                   7.7990(12)
_cell_length_c                   33.363(5)
_cell_measurement_reflns_used    2740
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      47.810
_cell_measurement_theta_min      4.884
_cell_volume                     3762.5(10)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SHELXTL'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_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  0.1148
_diffrn_reflns_av_sigmaI/netI    0.0807
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -16
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       38
_diffrn_reflns_limit_l_min       -40
_diffrn_reflns_number            18529
_diffrn_reflns_theta_full        25.50
_diffrn_reflns_theta_max         25.50
_diffrn_reflns_theta_min         1.86
_exptl_absorpt_coefficient_mu    0.093
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.7851
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            green
_exptl_crystal_density_diffrn    1.385
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prismatic
_exptl_crystal_F_000             1632
_exptl_crystal_size_max          0.309
_exptl_crystal_size_mid          0.147
_exptl_crystal_size_min          0.112
_refine_diff_density_max         0.233
_refine_diff_density_min         -0.229
_refine_diff_density_rms         0.056
_refine_ls_extinction_coef       0.0039(7)
_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   0.891
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     273
_refine_ls_number_reflns         3506
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.891
_refine_ls_R_factor_all          0.0880
_refine_ls_R_factor_gt           0.0581
_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^)+(0.0726P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1375
_refine_ls_wR_factor_ref         0.1509
_reflns_number_gt                2087
_reflns_number_total             3506
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b925234g.txt
_cod_data_source_block           cd29412
_cod_depositor_comments
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The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 1891 2012-01-12 08:04:46Z andrius 
;
_cod_original_cell_volume        3762.6(10)
_cod_original_sg_symbol_H-M      Pbca
_cod_database_code               7153311