Highly Efficient Synthesis of 3a,6a-Dihydrofuro[2,3-b]furans via a Novel Bicyclization.
Shu, Wen-Ming; Yang, Yan; Zhang, Dong-Xue; Wu, Liu-Ming; Zhu, Yan-Ping; Yin, Guo-Dong; Wu, An-Xin; Organic letters 15 (2013) 456–459; doi:10.1021/ol400016c

data_1508914
_publ_section_title
;
 Highly Efficient Synthesis of 3a,6a-Dihydrofuro[2,3-b]furans via a Novel
 Bicyclization.
;
_journal_issue                   3
_journal_name_full               'Organic letters'
_journal_page_first              456
_journal_page_last               459
_journal_paper_doi               10.1021/ol400016c
_journal_volume                  15
_journal_year                    2013
_chemical_formula_sum            'C22 H16 N2 O4'
_chemical_formula_weight         372.37
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 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                 91.258(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.8804(15)
_cell_length_b                   5.4346(7)
_cell_length_c                   31.653(4)
_cell_measurement_reflns_used    8463
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      30.19
_cell_measurement_theta_min      2.30
_cell_volume                     1871.2(4)
_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-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w 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  0.0299
_diffrn_reflns_av_sigmaI/netI    0.0247
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_l_max       39
_diffrn_reflns_limit_l_min       -39
_diffrn_reflns_number            17094
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         26.00
_diffrn_reflns_theta_min         1.97
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.092
_exptl_absorpt_correction_T_max  0.9908
_exptl_absorpt_correction_T_min  0.9863
_exptl_absorpt_correction_type   none
_exptl_crystal_density_meas      0
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             776
_exptl_crystal_size_max          0.15
_exptl_crystal_size_mid          0.12
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.201
_refine_diff_density_min         -0.198
_refine_diff_density_rms         0.046
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.121
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     254
_refine_ls_number_reflns         3648
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.121
_refine_ls_R_factor_all          0.0662
_refine_ls_R_factor_gt           0.0607
_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^)+(0.0523P)^2^+1.8657P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1606
_refine_ls_wR_factor_ref         0.1642
_reflns_number_gt                3270
_reflns_number_total             3648
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol400016c_si_004.cif
_cod_data_source_block           e:\121212i\work\mo_121212i_0m
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
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_sg_symbol_H-M      P2(1)/n
_cod_database_code               1508914