Diastereoselective intramolecular oxidopyrylium-alkene [5 + 2]-cycloaddition of substrates with a β-chiral center on alkene tethers: synthesis of 8-oxabicyclo-[3.2.1]-octenone heterocycles.
Ghosh, Arun K.; Hopkins, Denver; Organic & biomolecular chemistry 23 (2025) 10701–10723; doi:10.1039/d5ob01429h

data_7160851
_publ_section_title
;
 Diastereoselective intramolecular oxidopyrylium-alkene [5 +
 2]-cycloaddition of substrates with a &#x3b2;-chiral center on alkene
 tethers: synthesis of 8-oxabicyclo-[3.2.1]-octenone heterocycles.
;
_journal_issue                   47
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              10701
_journal_page_last               10723
_journal_paper_doi               10.1039/d5ob01429h
_journal_volume                  23
_journal_year                    2025
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C16 H16 O3'
_chemical_formula_sum            'C16 H16 O3'
_chemical_formula_weight         256.29
_chemical_name_systematic
;
(3R,4aS,8R,9aR)-3-phenyl-1,3,4,8,9,9a-hexahydro-5H-4a,8-epoxycyclohepta[c]pyran-5-one
;
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2019/3
_audit_update_record
;
2024-12-06 deposited with the CCDC.	2025-10-27 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   13.5957(4)
_cell_length_b                   5.5652(2)
_cell_length_c                   17.3345(5)
_cell_measurement_reflns_used    9880
_cell_measurement_temperature    150(2)
_cell_measurement_theta_max      32.4000
_cell_measurement_theta_min      2.9967
_cell_volume                     1311.58(7)
_computing_cell_refinement       'SAINT V8.40B (Bruker, 2020)'
_computing_data_collection       'Apex5 v2023.9-2 (Bruker, 2023)'
_computing_data_reduction        'SAINT V8.40B (Bruker, 2020)'
_computing_structure_refinement
;  
SHELXL-2019/2 (Sheldrick, 2015a, 2019), 
SHELXLE Rev1613 (H\"ubschle et al., 2011)
;
_computing_structure_solution    'SHELXT (Sheldrick, 2015b)'
_diffrn_ambient_temperature      150(2)
_diffrn_detector_area_resol_mean 7.4074
_diffrn_detector_type
'PhotonII charge-integrating pixel array (CPAD)'
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device       'three circle diffractometer'
_diffrn_measurement_device_type  'Bruker AXS D8 Quest'
_diffrn_measurement_method       'omega and phi scans'
_diffrn_radiation_monochromator  'Triumph curved graphite crystal'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0337
_diffrn_reflns_av_unetI/netI     0.0251
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       20
_diffrn_reflns_limit_h_min       -20
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -26
_diffrn_reflns_number            28105
_diffrn_reflns_point_group_measured_fraction_full 0.968
_diffrn_reflns_point_group_measured_fraction_max 0.948
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         33.172
_diffrn_reflns_theta_min         2.997
_diffrn_source                   'fine focus sealed tube X-ray source'
_diffrn_source_current           '30 mA'
_diffrn_source_voltage           '50 kV'
_exptl_absorpt_coefficient_mu    0.089
_exptl_absorpt_correction_T_max  0.7465
_exptl_absorpt_correction_T_min  0.6942
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
 SADABS 2016/2: Krause, L., Herbst-Irmer, R., Sheldrick G.M. & Stalke D.,
 J. Appl. Cryst. 48 (2015) 3-10
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.298
_exptl_crystal_description       block
_exptl_crystal_F_000             544
_exptl_crystal_size_max          0.397
_exptl_crystal_size_mid          0.227
_exptl_crystal_size_min          0.173
_refine_diff_density_max         0.245
_refine_diff_density_min         -0.184
_refine_diff_density_rms         0.038
_refine_ls_abs_structure_details
;
 Flack x determined using 1718 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.0(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.055
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     172
_refine_ls_number_reflns         4751
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.055
_refine_ls_R_factor_all          0.0438
_refine_ls_R_factor_gt           0.0353
_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^)+(0.0516P)^2^+0.0986P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0875
_refine_ls_wR_factor_ref         0.0927
_reflns_Friedel_coverage         0.847
_reflns_Friedel_fraction_full    0.934
_reflns_Friedel_fraction_max     0.894
_reflns_number_gt                4206
_reflns_number_total             4751
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5ob01429h2.cif
_cod_data_source_block           DRH-02-103_a
_cod_depositor_comments
'Adding full bibliography for 7160851--7160853.cif.'
_cod_database_code               7160851
_shelx_shelxl_version_number     2019/3
_shelx_estimated_absorpt_t_min   0.966
_shelx_estimated_absorpt_t_max   0.985
_shelx_res_checksum              16136