A regioselective sustainable neat approach to naphtho[2,3-<i>b</i>]thiophene-4,9-dione: detailed mechanistic study and DFT analysis.
Manik, Soumen K.; Ali, Sk Asraf; Sepay, Nayim; Deb, Aniruddha; Shit, Manik; Barik, Paritosh; Rath, Jyotirmoy; Maity, Kankan K.; Pal, Sudhir C.; Samanta, Shubhankar; Hazra, Nirmal K.; RSC advances 16 (2026) 6090–6105; doi:10.1039/d5ra08362a

data_7251743
_publ_section_title
;
 A regioselective sustainable neat approach to
 naphtho[2,3-<i>b</i>]thiophene-4,9-dione: detailed mechanistic study and
 DFT analysis.
;
_journal_issue                   7
_journal_name_full               'RSC advances'
_journal_page_first              6090
_journal_page_last               6105
_journal_paper_doi               10.1039/d5ra08362a
_journal_volume                  16
_journal_year                    2026
_chemical_formula_moiety         'C23 H19 N O4 S'
_chemical_formula_sum            'C23 H19 N2 O4 S'
_chemical_formula_weight         405.45
_chemical_name_systematic
'tert-butyl 4,9-dioxo-2-(phenylamino)-4,9-dihydronaphtho[2,3-b]thiophene-3-carboxylate'
_space_group_crystal_system      orthorhombic
_space_group_IT_number           29
_space_group_name_Hall           'P 2c -2ac'
_space_group_name_H-M_alt        'P c a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2016/6
_audit_update_record
;
2025-06-24 deposited with the CCDC.	2026-01-23 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.7952(3)
_cell_length_b                   11.7758(5)
_cell_length_c                   19.3258(8)
_cell_measurement_reflns_used    794
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25
_cell_measurement_theta_min      2
_cell_volume                     2001.58(14)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_structure_refinement  'SHELXL-2016/6 (Sheldrick, 2016)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2014)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.891
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0408
_diffrn_reflns_av_unetI/netI     0.0468
_diffrn_reflns_Laue_measured_fraction_full 0.997
_diffrn_reflns_Laue_measured_fraction_max 0.891
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            6451
_diffrn_reflns_point_group_measured_fraction_full 0.823
_diffrn_reflns_point_group_measured_fraction_max 0.696
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.087
_diffrn_reflns_theta_min         3.460
_exptl_absorpt_coefficient_mu    0.191
_exptl_crystal_colour            RED
_exptl_crystal_density_diffrn    1.345
_exptl_crystal_description       rectangular
_exptl_crystal_F_000             848
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: Ethyl Acetate and Petroleum Ether'
_exptl_crystal_size_max          0.60
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.15
_refine_diff_density_max         0.203
_refine_diff_density_min         -0.253
_refine_diff_density_rms         0.047
_refine_ls_abs_structure_details
;
 Flack x determined using 877 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.33(12)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.900
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     265
_refine_ls_number_reflns         3718
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.900
_refine_ls_R_factor_all          0.0617
_refine_ls_R_factor_gt           0.0508
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.1056P)^2^+0.4777P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1395
_refine_ls_wR_factor_ref         0.1577
_reflns_Friedel_coverage         0.516
_reflns_Friedel_fraction_full    0.636
_reflns_Friedel_fraction_max     0.488
_reflns_number_gt                3070
_reflns_number_total             5344
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5ra08362a2.cif
_cod_data_source_block           SMP-196_auto
_cod_database_code               7251743
_shelx_shelxl_version_number     2016/6
_shelx_res_checksum              54352