Biginelli Dihydropyrimidines: A Tunable Class of Alkyl Radical Precursors
Ratnam, Shahilan; Unone, Shreya; Alia, Nabeel; Hafeneger, Enyu Denny; Janssen-Müller, Daniel; Chemical Science  (2026) –; doi:10.1039/D6SC00376A

data_1576877
_publ_section_title
;
 Biginelli dihydropyrimidines: a tunable class of alkyl radical
 precursors.
;
_journal_issue                   18
_journal_name_full               'Chemical science'
_journal_page_first              8998
_journal_page_last               9005
_journal_paper_doi               10.1039/d6sc00376a
_journal_volume                  17
_journal_year                    2026
_chemical_absolute_configuration unk
_chemical_formula_moiety         'C16 H23 N3 O2'
_chemical_formula_sum            'C16 H23 N3 O2'
_chemical_formula_weight         289.37
_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   mixed
_atom_sites_solution_primary     dual
_audit_creation_date             2024-02-13
_audit_creation_method
;FinalCif V134 by Daniel Kratzert, Freiburg 2024, 
https://dkratzert.de/finalcif.html
;
_audit_update_record
;
2024-03-08 deposited with the CCDC.	2026-03-13 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   18.2950(5)
_cell_length_b                   10.1722(3)
_cell_length_c                   16.2289(5)
_cell_measurement_reflns_used    9952
_cell_measurement_temperature    100.00
_cell_measurement_theta_max      27.838
_cell_measurement_theta_min      2.363
_cell_volume                     3020.20(15)
_computing_cell_refinement       'SAINT V8.40B (?, 2016)'
_computing_data_collection
'Bruker BIS V6.2.15/2021-03-16 and APEX4 2022.1-1'
_computing_data_reduction        'SAINT V8.40B (?, 2016)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'XL  (Sheldrick, 2008)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      100.00
_diffrn_detector                 CPAD
_diffrn_detector_area_resol_mean 7.41
_diffrn_detector_type            'Bruker PHOTON III'
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'Bruker D8 VENTURE dual wavelength Mo/Cu'
_diffrn_measurement_method       '\w and \f scans'
_diffrn_measurement_specimen_support 'MiTeGen micromount'
_diffrn_radiation_monochromator  'mirror optics'
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0601
_diffrn_reflns_av_unetI/netI     0.0346
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       24
_diffrn_reflns_limit_h_min       -24
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            55755
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.999
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.910
_diffrn_reflns_theta_min         2.226
_diffrn_source                   'microfocus sealed X-ray tube'
_diffrn_source_current           1.0
_diffrn_source_power             0.05
_diffrn_source_type              'Incoatec I\ms'
_diffrn_source_voltage           50.0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.085
_exptl_absorpt_correction_T_max  1.0000
_exptl_absorpt_correction_T_min  0.8155
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.1313 before and 0.0577 after correction.
The Ratio of minimum to maximum transmission is 0.8155.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.273
_exptl_crystal_description       block
_exptl_crystal_F_000             1248
_exptl_crystal_recrystallization_method
'from a mixture of ethyl acetate and pentane.'
_exptl_crystal_size_max          0.299
_exptl_crystal_size_mid          0.158
_exptl_crystal_size_min          0.102
_refine_diff_density_max         0.442
_refine_diff_density_min         -0.284
_refine_diff_density_rms         0.077
_refine_ls_abs_structure_details
;
 Flack x determined using 2726 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.2(4)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.070
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     389
_refine_ls_number_reflns         7221
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.070
_refine_ls_R_factor_all          0.0586
_refine_ls_R_factor_gt           0.0515
_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^)+(0.0727P)^2^+1.5480P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1313
_refine_ls_wR_factor_ref         0.1371
_reflns_Friedel_coverage         0.931
_reflns_Friedel_fraction_full    0.999
_reflns_Friedel_fraction_max     0.998
_reflns_number_gt                6352
_reflns_number_total             7221
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d6sc00376a2.cif
_cod_data_source_block           2234_pna21
_cod_depositor_comments
'Adding full bibliography for 1576876--1576878.cif.'
_cod_original_cell_volume        3020.21(15)
_cod_database_code               1576877
_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. Restrained distances
 N1'-H1' = N1-H1
 0.88 with sigma of 0.02
3.a Ternary CH refined with riding coordinates:
 C3(H3), C4(H4), C3'(H3'), C4'(H4')
3.b Secondary CH2 refined with riding coordinates:
 C5(H5A,H5B), C6(H6A,H6B), C7(H7A,H7B), C8(H8A,H8B), C9(H9A,H9B), C15(H15A,
 H15B), C5'(H5'A,H5'B), C6'(H6'A,H6'B), C7'(H7'A,H7'B), C8'(H8'A,H8'B),
 C9'(H9'A,H9'B), C15'(H15C,H15D)
3.c Aromatic/amide H refined with riding coordinates:
 C13(H13), C14(H14), C13'(H13'), C14'(H14')
3.d Idealised Me refined as rotating group:
 C11(H11A,H11B,H11C), C16(H16A,H16B,H16C), C11'(H11D,H11E,H11F), C16'(H16D,
 H16E,H16F)
;
_olex2_submission_special_instructions 'No special instructions were received'
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_min   0.975
_shelx_estimated_absorpt_t_max   0.991
_diffrn_measurement_ambient_temperature_device_make 'Oxford Cryostream 800'
_shelx_res_checksum              64598