Metal-free Brønsted acid mediated synthesis of fully substituted thiophenes via chemo- and regioselective intramolecular cyclization of α,α'-bis(β-oxodithioesters) at room temperature.
Ramulu, B. Janaki; Koley, Suvajit; Singh, Maya Shankar; Organic & biomolecular chemistry 14 (2015) 434–439; doi:10.1039/c5ob02081f

data_7154772
_publ_section_title
;
 Metal-free Br\/onsted acid mediated synthesis of fully substituted
 thiophenes via chemo- and regioselective intramolecular cyclization of
 \a,\a'-bis(\b-oxodithioesters) at room temperature.
;
_journal_issue                   2
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              434
_journal_page_last               439
_journal_paper_doi               10.1039/c5ob02081f
_journal_volume                  14
_journal_year                    2015
_chemical_formula_sum            'C24 H24 O3 S4'
_chemical_formula_weight         488.70
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                96.786(5)
_cell_angle_beta                 92.066(4)
_cell_angle_gamma                103.632(4)
_cell_formula_units_Z            2
_cell_length_a                   8.0622(3)
_cell_length_b                   8.0832(5)
_cell_length_c                   19.3119(11)
_cell_measurement_reflns_used    2388
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      28.8358
_cell_measurement_theta_min      3.1875
_cell_volume                     1211.84(11)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector_area_resol_mean 16.0938
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.865
_diffrn_measurement_device_type  'Xcalibur, Eos'
_diffrn_measurement_method       '\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  0.0188
_diffrn_reflns_av_sigmaI/netI    0.0435
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -25
_diffrn_reflns_number            9169
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         28.90
_diffrn_reflns_theta_min         3.19
_exptl_absorpt_coefficient_mu    0.415
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.83647
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            Yellow
_exptl_crystal_density_diffrn    1.339
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       triclinic
_exptl_crystal_F_000             464
_exptl_crystal_size_max          0.3
_exptl_crystal_size_mid          0.2
_exptl_crystal_size_min          0.1
_refine_diff_density_max         0.243
_refine_diff_density_min         -0.347
_refine_diff_density_rms         0.048
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.874
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     280
_refine_ls_number_reflns         5500
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.874
_refine_ls_R_factor_all          0.0797
_refine_ls_R_factor_gt           0.0494
_refine_ls_shift/su_max          0.064
_refine_ls_shift/su_mean         0.019
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1082P)^2^+0.4851P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1407
_refine_ls_wR_factor_ref         0.1714
_reflns_number_gt                3790
_reflns_number_total             5500
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c5ob02081f3.cif
_cod_data_source_block           bjr-340
_cod_depositor_comments          'Adding full bibliography for 7154772.cif.'
_cod_database_code               7154772