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_7160852
_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_formula_moiety         'C11 H14 O3'
_chemical_formula_sum            'C11 H14 O3'
_chemical_formula_weight         194.22
_chemical_name_systematic
;
(3S*,4aS*,8R*,9aR*)-3-methyl-1,3,4,8,9,9a-hexahydro-5H-4a,8-epoxycyclohepta[c]pyran-5-one
;
_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
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2019/3
_audit_update_record
;
2025-07-07 deposited with the CCDC.	2025-10-27 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 108.072(5)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   8.8005(10)
_cell_length_b                   16.8892(19)
_cell_length_c                   6.6655(8)
_cell_measurement_reflns_used    9938
_cell_measurement_temperature    150(2)
_cell_measurement_theta_max      80.1207
_cell_measurement_theta_min      5.2870
_cell_volume                     941.84(19)
_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
'PhotonIII_C14 charge-integrating and photon counting pixel array'
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device       'four circle diffractometer'
_diffrn_measurement_device_type  'Bruker AXS D8 Quest'
_diffrn_measurement_method       'omega and phi scans'
_diffrn_radiation_monochromator  'HELIOS multilayer Montel optics'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0512
_diffrn_reflns_av_unetI/netI     0.0267
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 0.994
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       21
_diffrn_reflns_limit_k_min       -21
_diffrn_reflns_limit_l_max       8
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            25222
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.994
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         80.463
_diffrn_reflns_theta_min         5.238
_diffrn_source                   'I-mu-S 3.0 microsource X-ray tube'
_diffrn_source_current           '1.1 mA'
_diffrn_source_voltage           '50 kV'
_exptl_absorpt_coefficient_mu    0.811
_exptl_absorpt_correction_T_max  0.7543
_exptl_absorpt_correction_T_min  0.6349
_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    1.370
_exptl_crystal_description       needle
_exptl_crystal_F_000             416
_exptl_crystal_size_max          0.283
_exptl_crystal_size_mid          0.027
_exptl_crystal_size_min          0.010
_refine_diff_density_max         0.219
_refine_diff_density_min         -0.257
_refine_diff_density_rms         0.049
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.072
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     128
_refine_ls_number_reflns         2057
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.072
_refine_ls_R_factor_all          0.0419
_refine_ls_R_factor_gt           0.0375
_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^)+(0.0379P)^2^+0.3374P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0907
_refine_ls_wR_factor_ref         0.0944
_reflns_Friedel_coverage         0.000
_reflns_number_gt                1844
_reflns_number_total             2057
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5ob01429h2.cif
_cod_data_source_block           Me_O-allyl_a
_cod_depositor_comments
'Adding full bibliography for 7160851--7160853.cif.'
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               7160852
_shelx_shelxl_version_number     2019/3
_shelx_estimated_absorpt_t_min   0.803
_shelx_estimated_absorpt_t_max   0.992
_shelx_res_checksum              72399