A new mode of cyclobutenedione ring opening for the synthesis of 2-oxobut-3-enamides and tetrasubstituted furans.
Bennett, Ryan M.; Sun, Wei; Wilson, Dharyl C.; Light, Mark E.; Harrowven, David C.; Chemical communications (Cambridge, England) 57 (2021) 5694–5697; doi:10.1039/d1cc02097h

data_7128288
_publ_section_title
;
 A new mode of cyclobutenedione ring opening for the synthesis of
 2-oxobut-3-enamides and tetrasubstituted furans.
;
_journal_issue                   46
_journal_name_full               'Chemical communications (Cambridge, England)'
_journal_page_first              5694
_journal_page_last               5697
_journal_paper_doi               10.1039/d1cc02097h
_journal_volume                  57
_journal_year                    2021
_chemical_formula_moiety         'C18 H25 Br N2 O3'
_chemical_formula_sum            'C18 H25 Br N2 O3'
_chemical_formula_weight         397.31
_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   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2020-11-04
_audit_creation_method
;
Olex2 1.3
(compiled 2020.07.31 svn.rc2a77460 for OlexSys, GUI svn.r6145)
;
_audit_update_record
;
2020-11-04 deposited with the CCDC.	2021-05-05 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 95.8170(10)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   14.7511(2)
_cell_length_b                   10.26090(10)
_cell_length_c                   12.1428(2)
_cell_measurement_reflns_used    10180
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      31.8710
_cell_measurement_theta_min      3.3570
_cell_volume                     1828.46(4)
_computing_cell_refinement       'CrysAlisPro 1.171.40.37a (Rigaku OD, 2019)'
_computing_data_collection       'CrysAlisPro 1.171.40.37a (Rigaku OD, 2019)'
_computing_data_reduction        'CrysAlisPro 1.171.40.37a (Rigaku OD, 2019)'
_computing_molecular_graphics    'Olex2 1.3 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.3 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2018/3 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      100(2)
_diffrn_detector                 'CCD area detector'
_diffrn_detector_area_resol_mean 28.5714
_diffrn_detector_type            'Rigaku HG Saturn724+ (2x2 bin mode)'
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.947
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    -54.00  66.00   1.00    5.00    --  -22.50  38.00 -60.00  120
  2  \w   -111.00  12.00   1.00    5.00    --  -22.50 -60.00-180.00  123
  3  \w    -57.00  66.00   1.00    5.00    --  -22.50  60.00   0.00  123
  4  \w   -111.00  12.00   1.00    5.00    --  -22.50 -60.00 120.00  123
  5  \w    -57.00  43.00   1.00    5.00    --  -22.50  60.00 -90.00  100
;
_diffrn_measurement_device       'four-circle \k diffractometer'
_diffrn_measurement_device_type  'Rigaku AFC12 FRE-HF'
_diffrn_measurement_method       'profile data from \w-scans'
_diffrn_measurement_specimen_support 'MiTeGen MicroMesh'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0433924000
_diffrn_orient_matrix_UB_12      -0.0285745000
_diffrn_orient_matrix_UB_13      0.0140453000
_diffrn_orient_matrix_UB_21      -0.0207094000
_diffrn_orient_matrix_UB_22      -0.0620909000
_diffrn_orient_matrix_UB_23      0.0029519000
_diffrn_orient_matrix_UB_31      0.0045244000
_diffrn_orient_matrix_UB_32      -0.0103275000
_diffrn_orient_matrix_UB_33      -0.0569913000
_diffrn_radiation_collimation    0.3
_diffrn_radiation_monochromator  'Confocal mirrors, HF Varimax'
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_radiation_xray_symbol    K-L~3~
_diffrn_reflns_av_R_equivalents  0.0390
_diffrn_reflns_av_unetI/netI     0.0343
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.947
_diffrn_reflns_limit_h_max       21
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            29540
_diffrn_reflns_point_group_measured_fraction_full 0.998
_diffrn_reflns_point_group_measured_fraction_max 0.947
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         32.239
_diffrn_reflns_theta_min         3.031
_diffrn_source                   'Rotating-anode X-ray tube'
_diffrn_source_current           55.0
_diffrn_source_power             2.475
_diffrn_source_target            Mo
_diffrn_source_type              'Rigaku FR-E+ SuperBright'
_diffrn_source_voltage           45.0
_exptl_absorpt_coefficient_mu    2.266
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.58916
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.40.37a (Rigaku Oxford Diffraction, 2019)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.443
_exptl_crystal_description       '(cut) plate'
_exptl_crystal_F_000             824
_exptl_crystal_recrystallization_method
'The material was recrystallised from a mixture of DCM and hexane  by slow evaporation'
_exptl_crystal_size_max          0.139
_exptl_crystal_size_mid          0.075
_exptl_crystal_size_min          0.035
_refine_diff_density_max         0.541
_refine_diff_density_min         -0.405
_refine_diff_density_rms         0.074
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.056
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     223
_refine_ls_number_reflns         6123
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.056
_refine_ls_R_factor_all          0.0516
_refine_ls_R_factor_gt           0.0380
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0300P)^2^+1.0415P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0751
_refine_ls_wR_factor_ref         0.0801
_reflns_Friedel_coverage         0.000
_reflns_number_gt                5061
_reflns_number_total             6123
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d1cc02097h2.cif
_cod_data_source_block           2020sot0020_k1_100k
_cod_depositor_comments
'Adding full bibliography for 7128287--7128289.cif.'
_cod_database_code               7128288
_shelx_shelxl_version_number     2018/3
_chemical_oxdiff_formula         'C18 H25 Br N2 O3'
_chemical_oxdiff_usercomment     rb/9071/23.7p
_diffrn_measurement_device_type2 'Rigaku AFC12 (Right)'
_reflns_odcompleteness_completeness 99.74
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     30.44
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C13(H13), C16(H16)
2.b Aromatic/amide H refined with riding coordinates:
 C2(H2), C3(H3), C5(H5), C6(H6), C8(H8)
2.c Idealised Me refined as rotating group:
 C7(H7A,H7B,H7C), C12(H12A,H12B,H12C), C14(H14A,H14B,H14C), C15(H15A,H15B,
 H15C), C17(H17A,H17B,H17C), C18(H18A,H18B,H18C)
;
_shelx_res_checksum              80525
_olex2_date_sample_data_collection 2020-10-29
_olex2_date_sample_submission    2020-10-21
_olex2_diffrn_ambient_temperature_device 'Oxford Cryosystems'
_olex2_exptl_crystal_mounting_method
'The crystal was mounted on a MITIGEN holder with silicon oil'
_olex2_submission_original_sample_id rb/9071/23.7p
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.625
_oxdiff_exptl_absorpt_empirical_full_min 0.555