PIDA mediated oxidative annulation of aryl methyl ketones: a facile approach for the chemoselective synthesis of 5-substituted oxazoles.
Devaraju, Mohankumar; Prasad Dasappa, Jagadeesh; Organic & biomolecular chemistry 23 (2025) 2891–2895; doi:10.1039/d4ob01427h

data_7160379
_publ_section_title
;
 PIDA mediated oxidative annulation of aryl methyl ketones: a facile
 approach for the chemoselective synthesis of 5-substituted oxazoles.
;
_journal_issue                   12
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              2891
_journal_page_last               2895
_journal_paper_doi               10.1039/d4ob01427h
_journal_volume                  23
_journal_year                    2025
_chemical_formula_moiety         '2(C11 H11 N O3)'
_chemical_formula_sum            'C24 H24 N O5'
_chemical_formula_weight         406.44
_chemical_melting_point          156
_chemical_name_common            OXAZOLE
_chemical_name_systematic        5-(3,4-dimethoxyphenyl)oxazole
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     iterative
_audit_creation_date             2023-08-17
_audit_creation_method
;
Olex2 1.3
(compiled 2020.11.12 svn.r5f609507 for OlexSys, GUI svn.r6408)
;
_audit_update_record
;
2023-08-30 deposited with the CCDC.	2025-02-14 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 91.817(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   5.6243(2)
_cell_length_b                   8.6813(4)
_cell_length_c                   20.6205(9)
_cell_measurement_reflns_used    9932
_cell_measurement_temperature    298.15
_cell_measurement_theta_max      29.47
_cell_measurement_theta_min      2.97
_cell_volume                     1006.32(7)
_computing_cell_refinement       'SAINT V8.40B (?, 2016)'
_computing_data_reduction        'SAINT V8.40B (?, 2016)'
_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    'olex2.solve 1.3 (Bourhis et al., 2015)'
_diffrn_ambient_temperature      298.15
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.995
_diffrn_measurement_device_type
'Bruker D8 VENTURE diffractometer with PHOTON II detector'
_diffrn_measurement_method       '\w and \f scan'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0227
_diffrn_reflns_av_unetI/netI     0.0184
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.995
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       28
_diffrn_reflns_limit_l_min       -28
_diffrn_reflns_number            26669
_diffrn_reflns_point_group_measured_fraction_full 0.998
_diffrn_reflns_point_group_measured_fraction_max 0.992
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.634
_diffrn_reflns_theta_min         2.546
_exptl_absorpt_coefficient_mu    0.094
_exptl_absorpt_correction_T_max  0.8622
_exptl_absorpt_correction_T_min  0.7984
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.0488 before and 0.0428 after correction.
The Ratio of minimum to maximum transmission is 0.9260.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.341
_exptl_crystal_description       block
_exptl_crystal_F_000             430
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: Ethanol'
_exptl_crystal_size_max          0.342
_exptl_crystal_size_mid          0.179
_exptl_crystal_size_min          0.097
_refine_diff_density_max         0.295
_refine_diff_density_min         -0.419
_refine_diff_density_rms         0.105
_refine_ls_abs_structure_details
;
 Flack x determined using 2189 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.04(17)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.151
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     275
_refine_ls_number_reflns         5642
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.151
_refine_ls_R_factor_all          0.0485
_refine_ls_R_factor_gt           0.0414
_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^)+(0.0889P)^2^+0.0220P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1193
_refine_ls_wR_factor_ref         0.1343
_reflns_Friedel_coverage         0.878
_reflns_Friedel_fraction_full    0.997
_reflns_Friedel_fraction_max     0.989
_reflns_number_gt                5205
_reflns_number_total             5642
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d4ob01427h2.cif
_cod_data_source_block           ag16-r
_cod_depositor_comments
'Adding full bibliography for 7160379--7160380.cif.'
_cod_database_code               7160379
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_max   0.991
_shelx_estimated_absorpt_t_min   0.969
_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 Aromatic/amide H refined with riding coordinates:
 C3(H3), C4(H4), C7(H7), C9(H9), C10(H10), C16(H16), C19(H19), C20(H20),
 C21(H21), C24(H24)
2.b Idealised Me refined as rotating group:
 C1(H1A,H1B,H1C), C12(H12A,H12B,H12C), C13(H13A,H13B,H13C), C22(H22A,H22B,H22C)
;
_olex2_submission_special_instructions 'No special instructions were received'