Facile synthesis of 2-alkynyl oxazoles via a Ce(OTf)<sub>3</sub>-catalyzed cascade reaction of alkynyl carboxylic acids with tert-butyl isocyanide.
Cao, Ming; Teng, Qing-Hu; Xi, Zhi-Wei; Liu, Li-Qiu; Gu, Ren-Yong; Wang, Ying-Chun; Organic & biomolecular chemistry 18 (2020) 655–659; doi:10.1039/c9ob02337b

data_7157273
_publ_section_title
;
 Facile synthesis of 2-alkynyl oxazoles via a
 Ce(OTf)<sub>3</sub>-catalyzed cascade reaction of alkynyl carboxylic
 acids with tert-butyl isocyanide.
;
_journal_issue                   4
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              655
_journal_page_last               659
_journal_paper_doi               10.1039/c9ob02337b
_journal_volume                  18
_journal_year                    2020
_chemical_formula_moiety         'C27 H38 N6 O2'
_chemical_formula_sum            'C27 H38 N6 O2'
_chemical_formula_weight         478.63
_space_group_crystal_system      orthorhombic
_space_group_IT_number           61
_space_group_name_Hall           '-P 2ac 2ab'
_space_group_name_H-M_alt        'P b c a'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2019-10-17
_audit_creation_method
;
Olex2 1.3-alpha
(compiled 2019.10.11 svn.r3662 for OlexSys, GUI svn.r5962)
;
_audit_update_record
;
2019-10-18 deposited with the CCDC.	2019-12-24 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   19.2320(3)
_cell_length_b                   11.92476(17)
_cell_length_c                   23.5435(4)
_cell_measurement_reflns_used    5341
_cell_measurement_temperature    100.00(10)
_cell_measurement_theta_max      73.3710
_cell_measurement_theta_min      3.7440
_cell_volume                     5399.40(15)
_computing_cell_refinement       'CrysAlisPro 1.171.38.43f (Rigaku OD, 2015)'
_computing_data_collection       'CrysAlisPro 1.171.38.43f (Rigaku OD, 2015)'
_computing_data_reduction        'CrysAlisPro 1.171.38.43f (Rigaku OD, 2015)'
_computing_molecular_graphics    'Olex2 1.3-alpha (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.3-alpha (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL 2018/3 (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT n/a (Sheldrick, 2015)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      100.00(10)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 5.2684
_diffrn_detector_type            AtlasS2
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.980
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w      8.00  44.00   1.00    1.00    --   40.98 -99.00  30.00   36
  2  \w     73.00 118.00   1.00    1.50    --  106.95-125.00 150.00   45
  3  \w     87.00 112.00   1.00    1.50    --  106.95-103.00 157.00   25
  4  \w     79.00 145.00   1.00    1.50    --  106.95  30.00 120.00   66
  5  \w    108.00 177.00   1.00    1.50    --  106.95 125.00   0.00   69
  6  \w    151.00 178.00   1.00    1.50    --  106.95  77.00-180.00   27
  7  \w     82.00 147.00   1.00    1.50    --  106.95  77.00-180.00   65
  8  \w     44.00  81.00   1.00    1.00    --   40.98-125.00-120.00   37
  9  \w   -113.00 -16.00   1.00    1.00    --  -40.98 -38.00 150.00   97
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'SuperNova, Dual, Cu at zero, AtlasS2'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0429992000
_diffrn_orient_matrix_UB_12      -0.0048445000
_diffrn_orient_matrix_UB_13      -0.0551448000
_diffrn_orient_matrix_UB_21      -0.0600507000
_diffrn_orient_matrix_UB_22      -0.0618894000
_diffrn_orient_matrix_UB_23      -0.0298998000
_diffrn_orient_matrix_UB_31      -0.0310125000
_diffrn_orient_matrix_UB_32      0.1132665000
_diffrn_orient_matrix_UB_33      -0.0186667000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0358
_diffrn_reflns_av_unetI/netI     0.0400
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.980
_diffrn_reflns_limit_h_max       23
_diffrn_reflns_limit_h_min       -22
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       27
_diffrn_reflns_limit_l_min       -29
_diffrn_reflns_number            14096
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.980
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         73.621
_diffrn_reflns_theta_min         3.755
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    0.607
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.74192
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.38.43f (Rigaku Oxford Diffraction, 2015)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.178
_exptl_crystal_description       block
_exptl_crystal_F_000             2064
_exptl_crystal_size_max          0.12
_exptl_crystal_size_mid          0.11
_exptl_crystal_size_min          0.1
_refine_diff_density_max         0.469
_refine_diff_density_min         -0.443
_refine_diff_density_rms         0.047
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.037
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     322
_refine_ls_number_reflns         5342
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.037
_refine_ls_R_factor_all          0.0540
_refine_ls_R_factor_gt           0.0435
_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^)+(0.0551P)^2^+1.2656P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1067
_refine_ls_wR_factor_ref         0.1146
_reflns_Friedel_coverage         0.000
_reflns_number_gt                4392
_reflns_number_total             5342
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c9ob02337b2.cif
_cod_data_source_block           dq-57
_cod_depositor_comments
'Adding full bibliography for 7157272--7157273.cif.'
_cod_database_code               7157273
_shelx_shelxl_version_number     2018/3
_reflns_odcompleteness_completeness 99.94
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     66.97
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups, All N(H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C13(H13)
2.b Secondary CH2 refined with riding coordinates:
 C12(H12A,H12B), C14(H14A,H14B), C18(H18A,H18B), C15(H15A,H15B), C16(H16A,
 H16B), C17(H17A,H17B)
2.c Aromatic/amide H refined with riding coordinates:
 N1(H1), N3(H3), C7(H7), C11(H11), C8(H8), C9(H9), C10(H10)
2.d Idealised Me refined as rotating group:
 C20(H20A,H20B,H20C), C26(H26A,H26B,H26C), C25(H25A,H25B,H25C), C27(H27A,H27B,
 H27C), C21(H21A,H21B,H21C), C22(H22A,H22B,H22C)
;
_shelx_res_checksum              47075
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.710
_oxdiff_exptl_absorpt_empirical_full_min 0.473