6Pi e- versus 8pi e- electrocyclization of 1-aryl- and heteroaryl-substituted (1Z,3Z)-1,3,5-hexatrienes: a matter of aromaticity.
García-Rubín, Silvia; Varela, Jesús A; Castedo, Luis; Saá, Carlos; Organic letters 11 (2009) 983–986; doi:10.1021/ol802925q

data_1503794
_publ_section_title
;
 6Pi e- versus 8pi e- electrocyclization of 1-aryl- and
 heteroaryl-substituted (1Z,3Z)-1,3,5-hexatrienes: a matter of
 aromaticity.
;
_journal_issue                   4
_journal_name_full               'Organic letters'
_journal_page_first              983
_journal_page_last               986
_journal_paper_doi               10.1021/ol802925q
_journal_volume                  11
_journal_year                    2009
_chemical_absolute_configuration rm
_chemical_compound_source        'synthesis as described'
_chemical_formula_moiety         'C20 H22 O4'
_chemical_formula_sum            'C20 H22 O4'
_chemical_formula_weight         326.38
_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'
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_date             2008-09-03T11:25:10-00:00
_audit_creation_method           'WinGX routine CIF_UPDATE'
_cell_angle_alpha                90.000(5)
_cell_angle_beta                 95.221(5)
_cell_angle_gamma                90.000(5)
_cell_formula_units_Z            4
_cell_length_a                   6.121(5)
_cell_length_b                   34.927(5)
_cell_length_c                   8.130(5)
_cell_measurement_reflns_used    3151
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      23.75
_cell_measurement_theta_min      2.58
_cell_measurement_wavelength     0.71073
_cell_volume                     1730.9(18)
_computing_cell_refinement       'APPEX2 (BRUKER AXS, 2005)'
_computing_data_collection       'APPEX2 (BRUKER AXS, 2005)'
_computing_data_reduction        'APPEX2 (BRUKER AXS, 2005)'
_computing_molecular_graphics    'Ortep-3 for Windows (Farrugia, 1997)'
_computing_publication_material  'WinGX publication routines (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-86 (Sheldrick, 1986)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'BRUKER APPEX-II CCD'
_diffrn_measurement_method       'omega and phi scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.7107
_diffrn_reflns_av_R_equivalents  0.0922
_diffrn_reflns_av_unetI/netI     0.0915
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       43
_diffrn_reflns_limit_k_min       -43
_diffrn_reflns_limit_l_max       10
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            26579
_diffrn_reflns_theta_full        26.35
_diffrn_reflns_theta_max         26.35
_diffrn_reflns_theta_min         2.33
_exptl_absorpt_coefficient_mu    0.086
_exptl_absorpt_correction_T_max  0.7454
_exptl_absorpt_correction_T_min  0.5689
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'BRUKER SADABS'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.252
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             696
_exptl_crystal_size_max          0.19
_exptl_crystal_size_mid          0.08
_exptl_crystal_size_min          0.07
_refine_diff_density_max         0.434
_refine_diff_density_min         -0.305
_refine_diff_density_rms         0.075
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -1.4(15)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.038
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     440
_refine_ls_number_reflns         7037
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.038
_refine_ls_R_factor_all          0.0994
_refine_ls_R_factor_gt           0.0668
_refine_ls_shift/su_max          0
_refine_ls_shift/su_mean         0
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0871P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1516
_refine_ls_wR_factor_ref         0.1655
_reflns_number_gt                4988
_reflns_number_total             7037
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol802925q_si_002.cif
_cod_data_source_block           cs03sv2n
_cod_database_code               1503794