Tetraquinanes via [4 + 4] photocycloaddition/transannular ring closure.
Chen, Peiling; Carroll, Patrick J.; Sieburth, Scott McN; Organic letters 12 (2010) 4510–4512; doi:10.1021/ol101802s

data_1503205
_publ_section_title
;
 Tetraquinanes via [4 + 4] photocycloaddition/transannular ring closure.
;
_journal_issue                   20
_journal_name_full               'Organic letters'
_journal_page_first              4510
_journal_page_last               4512
_journal_paper_doi               10.1021/ol101802s
_journal_volume                  12
_journal_year                    2010
_chemical_absolute_configuration syn
_chemical_formula_sum            'C20 H25 Br2 N O4'
_chemical_formula_weight         503.23
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      19
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   6.6549(5)
_cell_length_b                   13.8696(11)
_cell_length_c                   21.4953(18)
_cell_measurement_temperature    143(1)
_cell_volume                     1984.0(3)
_computing_data_collection       'CrystalClear (Rigaku, 1999)'
_computing_data_reduction        'CrystalClear (Rigaku, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR97 (Altomare, 1999)'
_diffrn_ambient_temperature      143(1)
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device       'CCD Area Detector'
_diffrn_measurement_device_type  'Rigaku Mercury'
_diffrn_measurement_method       'phi and omega rotations'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'rotating anode'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.0281
_diffrn_reflns_av_sigmaI/netI    0.0494
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -27
_diffrn_reflns_number            10462
_diffrn_reflns_theta_full        27.48
_diffrn_reflns_theta_max         27.48
_diffrn_reflns_theta_min         2.94
_exptl_absorpt_coefficient_mu    4.112
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.6424
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_density_diffrn    1.685
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             1016
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.05
_exptl_crystal_size_min          0.04
_refine_diff_density_max         0.499
_refine_diff_density_min         -0.849
_refine_diff_density_rms         0.097
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.013(11)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.107
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     249
_refine_ls_number_reflns         4495
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.107
_refine_ls_R_factor_all          0.0462
_refine_ls_R_factor_gt           0.0392
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0453P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0843
_refine_ls_wR_factor_ref         0.0907
_reflns_number_gt                4013
_reflns_number_total             4495
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol101802s_si_002.cif
_cod_data_source_block           shelxl
_cod_original_sg_symbol_H-M      'P 21 21 21 '
_cod_database_code               1503205