Stereodivergent access to α- and β-azanucleosides <i>via</i> catalyst-free, achiral modulator-controlled iodocyclization: a concise synthesis of forodesine.
Zhong, Yangyang; Zeng, Jie; Li, Mingwei; Liang, Yuli; Guan, Shuman; Zhao, Kehan; Mu, Jiayi; Tang, Pei; Wang, Huijing; Chen, Fener; Chemical science 17 (2026) 4126–4136; doi:10.1039/d5sc08431h

data_1576699
_publ_section_title
;
 Stereodivergent access to &#x3b1;- and &#x3b2;-azanucleosides <i>via</i>
 catalyst-free, achiral modulator-controlled iodocyclization: a concise
 synthesis of forodesine.
;
_journal_issue                   8
_journal_name_full               'Chemical science'
_journal_page_first              4126
_journal_page_last               4136
_journal_paper_doi               10.1039/d5sc08431h
_journal_volume                  17
_journal_year                    2026
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C33 H30 I N5 O8 S'
_chemical_formula_sum            'C33 H30 I N5 O8 S'
_chemical_formula_weight         783.58
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2024-05-17
_audit_creation_method
;
Olex2 1.3
(compiled 2020.11.12 svn.r5f609507 for OlexSys, GUI svn.r6408)
;
_audit_update_record
;
2024-08-19 deposited with the CCDC.	2025-12-15 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   7.3460(4)
_cell_length_b                   26.0025(15)
_cell_length_c                   34.850(2)
_cell_measurement_reflns_used    9036
_cell_measurement_temperature    255(2)
_cell_measurement_theta_max      23.251
_cell_measurement_theta_min      2.337
_cell_volume                     6656.9(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 2014/7 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_temperature      255.0
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.995
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0973
_diffrn_reflns_av_unetI/netI     0.0692
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.995
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       33
_diffrn_reflns_limit_k_min       -33
_diffrn_reflns_limit_l_max       45
_diffrn_reflns_limit_l_min       -45
_diffrn_reflns_number            94520
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.994
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.687
_diffrn_reflns_theta_min         1.920
_diffrn_source_current           1.4
_diffrn_source_power             0.07
_diffrn_source_voltage           50.0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    1.084
_exptl_absorpt_correction_T_max  0.7456
_exptl_absorpt_correction_T_min  0.6179
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.1643 before and 0.0766 after correction.
The Ratio of minimum to maximum transmission is 0.8287.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            'clear light colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_modifier   light
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.564
_exptl_crystal_description       needle
_exptl_crystal_F_000             3168
_exptl_crystal_size_max          0.48
_exptl_crystal_size_mid          0.08
_exptl_crystal_size_min          0.02
_refine_diff_density_max         0.363
_refine_diff_density_min         -0.567
_refine_diff_density_rms         0.065
_refine_ls_abs_structure_details
;
 Flack x determined using 3362 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.008(9)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.031
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     867
_refine_ls_number_reflns         15499
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.031
_refine_ls_R_factor_all          0.0923
_refine_ls_R_factor_gt           0.0437
_refine_ls_shift/su_max          0.002
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0149P)^2^+3.1385P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0703
_refine_ls_wR_factor_ref         0.0849
_reflns_Friedel_coverage         0.795
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     0.993
_reflns_number_gt                10094
_reflns_number_total             15499
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc08431h2.cif
_cod_data_source_block           mo_tp_zyy_20240517_a_0ma_a
_cod_depositor_comments          'Adding full bibliography for 1576699.cif.'
_cod_original_cell_volume        6656.8(7)
_cod_database_code               1576699
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_max   0.979
_shelx_estimated_absorpt_t_min   0.624
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C8(H8), C9(H9), C33(H33), C40(H40), C41(H41), C53(H53)
2.b Secondary CH2 refined with riding coordinates:
 C5(H5A,H5B), C6(H6A,H6B), C11(H11A,H11B), C32(H32A,H32B), C38(H38A,H38B),
 C44(H44A,H44B), C45(H45A,H45B), C52(H52A,H52B)
2.c Aromatic/amide H refined with riding coordinates:
 C1(H1), C27(H27), C3(H3), C7(H7), C13(H13), C14(H14), C15(H15), C16(H16),
 C17(H17), C20(H20), C24(H24), C25(H25), C28(H28), C29(H29), C30(H30), C31(H31),
  C34(H34), C35(H35), C36(H36), C43(H43), C47(H47), C48(H48), C49(H49),
 C50(H50), C51(H51), C55(H55), C56(H56), C60(H60), C61(H61), C65(H65), C67(H67),
  C68(H68)
2.d Idealised Me refined as rotating group:
 C22(H22A,H22B,H22C), C64(H64A,H64B,H64C)
;
_shelx_res_checksum              86754
_shelx_hkl_checksum              90228
_olex2_submission_special_instructions 'No special instructions were received'