A Hetero Diels-Alder Approach to the Synthesis of Chromans (3,4-Dihydrobenzopyrans) Using Oxonium Ion Chemistry: The Oxa-Povarov Reaction
Rivka R. R. Taylor; Robert A. Batey; Journal of Organic Chemistry 78 (2013) 1404–1420; doi:10.1021/jo302328s

data_4027954
_publ_section_title
;
 A Hetero Diels-Alder Approach to the Synthesis of Chromans
 (3,4-Dihydrobenzopyrans) Using Oxonium Ion Chemistry: The Oxa-Povarov
 Reaction
;
_journal_name_full               'Journal of Organic Chemistry'
_journal_page_first              1404
_journal_page_last               1420
_journal_paper_doi               10.1021/jo302328s
_journal_volume                  78
_journal_year                    2013
_chemical_absolute_configuration unk
_chemical_formula_moiety         'C20 H17 N O'
_chemical_formula_sum            'C20 H17 N O'
_chemical_formula_weight         287.35
_space_group_IT_number           33
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   18.6617(10)
_cell_length_b                   5.4269(8)
_cell_length_c                   29.7664(13)
_cell_measurement_reflns_used    15893
_cell_measurement_temperature    150(1)
_cell_measurement_theta_max      27.5
_cell_measurement_theta_min      3.0
_cell_volume                     3014.6(5)
_computing_cell_refinement       'Denzo-SMN (Otwinowski & Minor, 1997)'
_computing_data_collection       'Collect (Nonius B.V., 1997-2002)'
_computing_data_reduction        Denzo-SMN
_computing_molecular_graphics    'PLATON (Spek, 2009)'
_computing_publication_material  'SHELXTL V6.1'
_computing_structure_refinement  'SHELXTL V6.1 (Sheldrick, 2008)'
_computing_structure_solution    'SIR-92 (Altomare et al., 1994)'
_diffrn_ambient_temperature      150(1)
_diffrn_detector_area_resol_mean 9
_diffrn_measured_fraction_theta_full 0.992
_diffrn_measured_fraction_theta_max 0.992
_diffrn_measurement_device_type  'Nonius KappaCCCD'
_diffrn_measurement_method       '\f scans and \w scans with \k offsets'
_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  0.0593
_diffrn_reflns_av_sigmaI/netI    0.0521
_diffrn_reflns_limit_h_max       24
_diffrn_reflns_limit_h_min       -23
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       26
_diffrn_reflns_limit_l_min       -38
_diffrn_reflns_number            15893
_diffrn_reflns_theta_full        27.50
_diffrn_reflns_theta_max         27.50
_diffrn_reflns_theta_min         3.00
_exptl_absorpt_coefficient_mu    0.078
_exptl_absorpt_correction_T_max  0.994
_exptl_absorpt_correction_T_min  0.753
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
multi-scan from symmetry-related measurements 
 Sortav (Blessing 1995)
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.266
_exptl_crystal_description       block
_exptl_crystal_F_000             1216
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.16
_refine_diff_density_max         0.182
_refine_diff_density_min         -0.217
_refine_diff_density_rms         0.047
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.042
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     397
_refine_ls_number_reflns         3486
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.042
_refine_ls_R_factor_all          0.0872
_refine_ls_R_factor_gt           0.0489
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0790P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1126
_refine_ls_wR_factor_ref         0.1348
_reflns_number_gt                2405
_reflns_number_total             3486
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            jo302328s_si_002.cif
_cod_data_source_block           k09232a
_cod_database_code               4027954