Short Total Synthesis of [<sup>15</sup>N<sub>5</sub>]-Cylindrospermopsins from <sup>15</sup>NH<sub>4</sub>Cl Enables Precise Quantification of Freshwater Cyanobacterial Contamination.
Mailyan, Artur K.; Chen, Joanna L.; Li, Weiwei; Keller, Arturo A.; Sternisha, Shawn M.; Miller, Brian G.; Zakarian, Armen; Journal of the American Chemical Society 140 (2018) 6027–6032; doi:10.1021/jacs.8b03071

data_4132361
_publ_section_title
;
 Short Total Synthesis of [<sup>15</sup>N<sub>5</sub>]-Cylindrospermopsins
 from <sup>15</sup>NH<sub>4</sub>Cl Enables Precise Quantification of
 Freshwater Cyanobacterial Contamination.
;
_journal_issue                   18
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              6027
_journal_page_last               6032
_journal_paper_doi               10.1021/jacs.8b03071
_journal_volume                  140
_journal_year                    2018
_chemical_absolute_configuration ad
_chemical_formula_sum            'C16 H25 N5 O7 S'
_chemical_formula_weight         431.47
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   mixed
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 110.96(2)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   9.881(11)
_cell_length_b                   9.166(10)
_cell_length_c                   11.040(12)
_cell_measurement_reflns_used    88
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      23.3
_cell_measurement_theta_min      2.3
_cell_volume                     933.7(18)
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.980
_diffrn_measured_fraction_theta_max 0.980
_diffrn_measurement_device_type  'Bruker Kappa Apex II'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0337
_diffrn_reflns_av_unetI/netI     0.1120
_diffrn_reflns_Laue_measured_fraction_full 0.980
_diffrn_reflns_Laue_measured_fraction_max 0.980
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            3589
_diffrn_reflns_point_group_measured_fraction_full 0.874
_diffrn_reflns_point_group_measured_fraction_max 0.874
_diffrn_reflns_theta_full        24.929
_diffrn_reflns_theta_max         24.929
_diffrn_reflns_theta_min         1.975
_exptl_absorpt_coefficient_mu    0.226
_exptl_absorpt_correction_T_max  0.7451
_exptl_absorpt_correction_T_min  0.6060
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.535
_exptl_crystal_description       plate
_exptl_crystal_F_000             456
_exptl_crystal_size_max          0.25
_exptl_crystal_size_mid          0.15
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.365
_refine_diff_density_min         -0.447
_refine_diff_density_rms         0.071
_refine_ls_abs_structure_details
;
 Flack x determined using 562 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.2(2)
_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     267
_refine_ls_number_reflns         2843
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.037
_refine_ls_R_factor_all          0.1197
_refine_ls_R_factor_gt           0.0711
_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^)+(0.0879P)^2^+0.0746P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1595
_refine_ls_wR_factor_ref         0.1808
_reflns_Friedel_coverage         0.667
_reflns_Friedel_fraction_full    0.752
_reflns_Friedel_fraction_max     0.752
_reflns_number_gt                1860
_reflns_number_total             2843
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja8b03071_si_002.cif
_cod_data_source_block           07182017_0m
_cod_original_cell_volume        933.6(17)
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               4132361
_shelx_shelxl_version_number     2014/7
_shelx_res_checksum              85098
_shelx_hkl_checksum              76735