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_7157272
_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         'C18 H23 N3 O2 S'
_chemical_formula_sum            'C18 H23 N3 O2 S'
_chemical_formula_weight         345.45
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2yn'
_space_group_name_H-M_alt        'P 1 21/n 1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     dual
_audit_creation_date             2018-10-24
_audit_creation_method
;
Olex2 1.2
(compiled 2018.05.29 svn.r3508 for OlexSys, GUI svn.r5506)
;
_audit_update_record
;
2019-09-02 deposited with the CCDC.	2019-12-24 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 100.107(3)
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   11.6688(3)
_cell_length_b                   10.6008(3)
_cell_length_c                   31.1741(9)
_cell_measurement_reflns_used    7412
_cell_measurement_temperature    100.00(10)
_cell_measurement_theta_max      73.4370
_cell_measurement_theta_min      3.8670
_cell_volume                     3796.35(19)
_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 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT (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 0.965
_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    -11.00  54.00   1.00    1.00    --   41.11 -38.00  90.00   65
  2  \w     41.00  89.00   1.00    1.00    --   41.11-137.00 -48.00   48
  3  \w     26.00 103.00   1.00    1.00    --  106.95 -95.00-150.00   77
  4  \w     87.00 177.00   1.00    1.00    --  106.95  30.00 -60.00   90
  5  \w    116.00 141.00   1.00    1.00    --  106.95 110.00 -59.00   25
  6  \w    102.00 162.00   1.00    1.00    --  106.95 125.00-120.00   60
  7  \w     91.00 178.00   1.00    1.00    --  106.95 133.00-162.00   87
  8  \w    149.00 176.00   1.00    1.00    --  106.95 125.00  60.00   27
  9  \w     98.00 176.00   1.00    1.00    --  106.95 125.00 120.00   78
 10  \w   -114.00  -5.00   1.00    1.00    --  -41.11 -19.00-120.00  109
;
_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      0.0330154000
_diffrn_orient_matrix_UB_12      0.0401355000
_diffrn_orient_matrix_UB_13      0.0480719000
_diffrn_orient_matrix_UB_21      0.0192398000
_diffrn_orient_matrix_UB_22      0.1362731000
_diffrn_orient_matrix_UB_23      -0.0143884000
_diffrn_orient_matrix_UB_31      -0.1285161000
_diffrn_orient_matrix_UB_32      0.0307770000
_diffrn_orient_matrix_UB_33      0.0010462000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0356
_diffrn_reflns_av_unetI/netI     0.0445
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.965
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       38
_diffrn_reflns_limit_l_min       -38
_diffrn_reflns_number            14668
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.965
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         73.752
_diffrn_reflns_theta_min         2.880
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    1.629
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.63936
_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    1.209
_exptl_crystal_description       block
_exptl_crystal_F_000             1472
_exptl_crystal_size_max          0.13
_exptl_crystal_size_mid          0.12
_exptl_crystal_size_min          0.11
_refine_diff_density_max         0.519
_refine_diff_density_min         -0.397
_refine_diff_density_rms         0.062
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.038
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     471
_refine_ls_number_reflns         7409
_refine_ls_number_restraints     8
_refine_ls_restrained_S_all      1.048
_refine_ls_R_factor_all          0.0638
_refine_ls_R_factor_gt           0.0564
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0785P)^2^+1.4824P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1439
_refine_ls_wR_factor_ref         0.1515
_reflns_Friedel_coverage         0.000
_reflns_number_gt                6360
_reflns_number_total             7409
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c9ob02337b2.cif
_cod_data_source_block           dq_13_2
_cod_depositor_comments
'Adding full bibliography for 7157272--7157273.cif.'
_cod_database_code               7157272
_shelx_shelxl_version_number     2017/1
_shelx_estimated_absorpt_t_max   0.841
_shelx_estimated_absorpt_t_min   0.816
_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 N(H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2. Restrained distances
 C00Y-C0AA
 1.2 with sigma of 0.02
3. Rigid bond restraints
 C00Y, C0AA
 with sigma for 1-2 distances of 0.01 and sigma for 1-3 distances of 0.01
4. Uiso/Uaniso restraints and constraints
C00Y \\sim C0AA: within 2A with sigma of 0.002 and sigma for terminal atoms of
0.004
5. Others
 Sof(S0AB)=1-FVAR(1)
 Sof(S0AA)=FVAR(1)
 Fixed Sof: H0AB(0.5) H0AA(0.5)
6.a Aromatic/amide H refined with riding coordinates:
 N3(H3), N2(H2), N00C(H00C), N00D(H00D), C2(H2A), C4(H4), C3(H3A)
6.b Idealised Me refined as rotating group:
 C18(H18A,H18B,H18C), C17(H17A,H17B,H17C), C013(H01A,H01B,H01C), C014(H01D,
 H01E,H01F), C12(H12A,H12B,H12C), C14(H14A,H14B,H14C), C16(H16A,H16B,H16C),
 C018(H01G,H01H,H01I), C019(H01J,H01K,H01L), C13(H13A,H13B,H13C), C01B(H01M,
 H01N,H01O), C01C(H01P,H01Q,H01R)
;
_shelx_res_checksum              7838
_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
- Detector area scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.384
_oxdiff_exptl_absorpt_empirical_full_min 0.724