Synthesis of Highly Functionalized Spirobutenolides via a Nitroalkane-Mediated Ring Contraction of 2-Oxobenzo[ h]chromenes through Denitration.
Elagamy, Amr; Shaw, Ranjay; Panwar, Rahul; Shally, ?; Ram, Vishnu Ji; Pratap, Ramendra; The Journal of organic chemistry 84 (2019) 1154–1161; doi:10.1021/acs.joc.8b02257

data_4037534
_publ_section_title
;
 Synthesis of Highly Functionalized Spirobutenolides via a
 Nitroalkane-Mediated Ring Contraction of 2-Oxobenzo[ h]chromenes through
 Denitration.
;
_journal_issue                   3
_journal_name_full               'The Journal of organic chemistry'
_journal_page_first              1154
_journal_page_last               1161
_journal_paper_doi               10.1021/acs.joc.8b02257
_journal_volume                  84
_journal_year                    2019
_chemical_formula_moiety         'C22 H24 N2 O3'
_chemical_formula_sum            'C22 H24 N2 O3'
_chemical_formula_weight         364.43
_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-2016/6
_cell_angle_alpha                90
_cell_angle_beta                 99.871(5)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.6886(5)
_cell_length_b                   12.9245(9)
_cell_length_c                   17.4560(12)
_cell_measurement_reflns_used    3454
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      22.2450
_cell_measurement_theta_min      3.6340
_cell_volume                     1931.2(2)
_computing_cell_refinement       'CrysAlisPro, Agilent Technologies'
_computing_data_collection       'CrysAlisPro, Agilent Technologies'
_computing_data_reduction        'CrysAlisPro, Agilent Technologies'
_computing_structure_refinement  'SHELXL-2016/6 (Sheldrick, 2016)'
_computing_structure_solution    'SHELXL-2016/6 (Sheldrick, 2016)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'xcalibur sapphire3'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0813
_diffrn_reflns_av_unetI/netI     0.0506
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.999
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            22924
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.999
_diffrn_reflns_theta_full        25.000
_diffrn_reflns_theta_max         25.000
_diffrn_reflns_theta_min         2.854
_exptl_absorpt_coefficient_mu    0.084
_exptl_crystal_colour            WHITE
_exptl_crystal_density_diffrn    1.253
_exptl_crystal_description       BLOCK
_exptl_crystal_F_000             776
_exptl_crystal_size_max          0.220
_exptl_crystal_size_mid          0.200
_exptl_crystal_size_min          0.180
_refine_diff_density_max         0.239
_refine_diff_density_min         -0.279
_refine_diff_density_rms         0.043
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.977
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     248
_refine_ls_number_reflns         3409
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.977
_refine_ls_R_factor_all          0.1047
_refine_ls_R_factor_gt           0.0741
_refine_ls_shift/su_max          0.006
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.1092P)^2^+1.0930P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2005
_refine_ls_wR_factor_ref         0.2222
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2350
_reflns_number_total             3409
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            jo8b02257_si_002.cif
_cod_data_source_block           shelx
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               4037534
_shelx_shelxl_version_number     2016/6
_shelx_estimated_absorpt_t_min   0.982
_shelx_estimated_absorpt_t_max   0.985
_shelx_res_checksum              39526
_shelx_hkl_checksum              2301