A Brønsted acid catalyzed tandem reaction for the diastereoselective synthesis of cyclobuta-fused tetrahydroquinoline carboxylic esters.
Marras, Valentina; Caboni, Pierluigi; Secci, Francesco; Guillot, Régis; Aitken, David J.; Frongia, Angelo; Organic & biomolecular chemistry 19 (2021) 8912–8916; doi:10.1039/d1ob01518d

data_7158328
_publ_section_title
;
 A Br\/onsted acid catalyzed tandem reaction for the diastereoselective
 synthesis of cyclobuta-fused tetrahydroquinoline carboxylic esters.
;
_journal_issue                   41
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              8912
_journal_page_last               8916
_journal_paper_doi               10.1039/d1ob01518d
_journal_volume                  19
_journal_year                    2021
_chemical_formula_moiety         'C18 H18 N2 O2'
_chemical_formula_sum            'C18 H18 N2 O2'
_chemical_formula_weight         294.34
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   mixed
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2021-05-31 deposited with the CCDC.	2021-09-30 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 95.4260(10)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   6.56070(10)
_cell_length_b                   7.5167(2)
_cell_length_c                   28.7149(6)
_cell_measurement_reflns_used    9897
_cell_measurement_temperature    100(1)
_cell_measurement_theta_max      66.62
_cell_measurement_theta_min      3.09
_cell_volume                     1409.72(5)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX3'
_computing_data_reduction        'Bruker SAINT'
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_computing_structure_solution    'SHELXS-97 (Sheldrick 2008)'
_diffrn_ambient_temperature      100(1)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker VENTURE PHOTON100 CMOS'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0492
_diffrn_reflns_av_unetI/netI     0.0217
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       34
_diffrn_reflns_limit_l_min       -34
_diffrn_reflns_number            25459
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.998
_diffrn_reflns_theta_full        66.758
_diffrn_reflns_theta_max         66.758
_diffrn_reflns_theta_min         3.092
_exptl_absorpt_coefficient_mu    0.733
_exptl_absorpt_correction_T_max  0.9528
_exptl_absorpt_correction_T_min  0.8954
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Bruker APEX3'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.387
_exptl_crystal_description       plate
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.070
_exptl_crystal_size_mid          0.050
_exptl_crystal_size_min          0.040
_refine_diff_density_max         0.201
_refine_diff_density_min         -0.245
_refine_diff_density_rms         0.051
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.118
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     195
_refine_ls_number_reflns         2486
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.118
_refine_ls_R_factor_all          0.0525
_refine_ls_R_factor_gt           0.0457
_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^)+(0.0266P)^2^+1.6278P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0992
_refine_ls_wR_factor_ref         0.1019
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2237
_reflns_number_total             2486
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d1ob01518d2.cif
_cod_data_source_block           5
_cod_depositor_comments
'Adding full bibliography for 7158328--7158329.cif.'
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               7158328
_shelx_estimated_absorpt_t_min   0.956
_shelx_estimated_absorpt_t_max   0.974
_shelx_res_checksum              90895