N-oxides of adenosine-type nucleosides undergo pyrimidine ring opening and closure to give 5-amino-4-(1,2,4-oxadiazol-3-yl)imidazole derivatives.
Nowak, Ireneusz; Cannon, John F.; Robins, Morris J.; Organic letters 8 (2006) 4565–4568; doi:10.1021/ol061715v

data_1506182
_publ_section_title
;
 N-oxides of adenosine-type nucleosides undergo pyrimidine ring opening
 and closure to give 5-amino-4-(1,2,4-oxadiazol-3-yl)imidazole
 derivatives.
;
_journal_issue                   20
_journal_name_full               'Organic letters'
_journal_page_first              4565
_journal_page_last               4568
_journal_paper_doi               10.1021/ol061715v
_journal_volume                  8
_journal_year                    2006
_chemical_absolute_configuration ad
_chemical_formula_sum            'C11 H15 N5 O5'
_chemical_formula_weight         297.28
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   6.1879(6)
_cell_length_b                   6.6386(6)
_cell_length_c                   30.879(3)
_cell_measurement_reflns_used    3825
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      50.28
_cell_measurement_theta_min      7.26
_cell_volume                     1268.5(2)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.964
_diffrn_measured_fraction_theta_max 0.964
_diffrn_measurement_device_type  'Bruker Nonius Apex II CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  'Montel 200 mirrors'
_diffrn_radiation_source         'Bruker Nonius FR591 rotating anode'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0336
_diffrn_reflns_av_sigmaI/netI    0.0304
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_l_max       30
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            4454
_diffrn_reflns_theta_full        50.27
_diffrn_reflns_theta_max         50.27
_diffrn_reflns_theta_min         7.26
_exptl_absorpt_coefficient_mu    1.067
_exptl_absorpt_correction_T_max  0.7264
_exptl_absorpt_correction_T_min  0.6810
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS; Sheldrick, 2003'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.557
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       BLOCK
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.39
_exptl_crystal_size_mid          0.36
_exptl_crystal_size_min          0.32
_refine_diff_density_max         0.131
_refine_diff_density_min         -0.173
_refine_diff_density_rms         0.034
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.0(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.099
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     218
_refine_ls_number_reflns         1245
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.099
_refine_ls_R_factor_all          0.0320
_refine_ls_R_factor_gt           0.0312
_refine_ls_shift/su_max          0.003
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0572P)^2^+0.1436P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0806
_refine_ls_wR_factor_ref         0.0812
_reflns_number_gt                1211
_reflns_number_total             1245
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol061715vsi20060713_102004.cif
_cod_data_source_block           XL904
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 
;
_cod_original_sg_symbol_H-M      P2(1)2(1)2(1)
_cod_database_code               1506182