Intramolecular nitrone dipolar cycloadditions: control of regioselectivity and synthesis of naturally-occurring spirocyclic alkaloids.
Hodges, Alastair J.; Adams, Joseph P.; Bond, Andrew D.; Holmes, Andrew B.; Press, Neil J.; Roughley, Stephen D.; Ryan, John H.; Saubern, Simon; Smith, Catherine J.; Turnbull, Michael D.; Newton, Annabella F.; Organic & biomolecular chemistry 10 (2012) 8963–8974; doi:10.1039/c2ob26333e

data_7152688
_publ_section_title
;
 Intramolecular nitrone dipolar cycloadditions: control of
 regioselectivity and synthesis of naturally-occurring spirocyclic
 alkaloids.
;
_journal_issue                   45
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              8963
_journal_page_last               8974
_journal_paper_doi               10.1039/c2ob26333e
_journal_volume                  10
_journal_year                    2012
_chemical_absolute_configuration ad
_chemical_formula_sum            'C24 H41 N O2 Si'
_chemical_formula_weight         403.67
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_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                 98.831(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   7.7031(3)
_cell_length_b                   9.8991(6)
_cell_length_c                   15.8805(8)
_cell_measurement_reflns_used    4554
_cell_measurement_temperature    180(2)
_cell_measurement_theta_max      27.48
_cell_measurement_theta_min      1.00
_cell_volume                     1196.59(11)
_computing_cell_refinement       'HKL Scalepack (Otwinowski & Minor, 1997)'
_computing_data_collection       'Collect (Nonius, 1998)'
_computing_data_reduction
;
HKL Denzo and Scalepack (Otwinowski & Minor, 1997)
;
_computing_publication_material  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      180(2)
_diffrn_measured_fraction_theta_full 0.988
_diffrn_measured_fraction_theta_max 0.988
_diffrn_measurement_device_type  'Nonius KappaCCD'
_diffrn_measurement_method       'Thin slice \w and \f scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0432
_diffrn_reflns_av_sigmaI/netI    0.0650
_diffrn_reflns_limit_h_max       9
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            7454
_diffrn_reflns_theta_full        27.48
_diffrn_reflns_theta_max         27.48
_diffrn_reflns_theta_min         3.76
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.116
_exptl_absorpt_correction_T_max  1.120
_exptl_absorpt_correction_T_min  0.890
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Sortav Blessing (1995)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.120
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             444
_exptl_crystal_size_max          0.60
_exptl_crystal_size_mid          0.23
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.215
_refine_diff_density_min         -0.332
_refine_diff_density_rms         0.062
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.08(11)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.048
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     260
_refine_ls_number_reflns         4564
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.048
_refine_ls_R_factor_all          0.0586
_refine_ls_R_factor_gt           0.0439
_refine_ls_shift/su_max          0.008
_refine_ls_shift/su_mean         0.002
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0603P)^2^+0.0031P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1016
_refine_ls_wR_factor_ref         0.1107
_reflns_number_gt                3846
_reflns_number_total             4564
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            c2ob26333e.txt
_cod_data_source_block           ah0118
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               7152688