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_7152690
_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 unk
_chemical_formula_moiety         'C19 H24 N2 O2'
_chemical_formula_sum            'C19 H24 N2 O2'
_chemical_formula_weight         312.40
_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                 103.279(5)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   8.4675(15)
_cell_length_b                   11.662(2)
_cell_length_c                   8.6820(16)
_cell_measurement_reflns_used    5022
_cell_measurement_temperature    150(2)
_cell_measurement_theta_max      29.43
_cell_measurement_theta_min      3.4
_cell_volume                     834.4(3)
_computing_cell_refinement       'SAINT (Bruker, 1997)'
_computing_data_collection       'SMART (Bruker, 1997)'
_computing_data_reduction        SAINT
_computing_molecular_graphics    'SHELXTL (Bruker, 1997)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      150(2)
_diffrn_measured_fraction_theta_full 0.927
_diffrn_measured_fraction_theta_max 0.927
_diffrn_measurement_device_type  'Bruker SMART CCD'
_diffrn_measurement_method       '0.15 deg step phi scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'synchrotron gapped beam'
_diffrn_radiation_type           synchrotron
_diffrn_radiation_wavelength     0.6885
_diffrn_reflns_av_R_equivalents  0.0575
_diffrn_reflns_av_sigmaI/netI    0.0779
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            7499
_diffrn_reflns_theta_full        29.29
_diffrn_reflns_theta_max         29.29
_diffrn_reflns_theta_min         2.33
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.081
_exptl_absorpt_correction_T_max  0.9992
_exptl_absorpt_correction_T_min  0.9968
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Bruker, 1997)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.243
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             336
_exptl_crystal_size_max          0.04
_exptl_crystal_size_mid          0.02
_exptl_crystal_size_min          0.01
_refine_diff_density_max         0.550
_refine_diff_density_min         -0.391
_refine_diff_density_rms         0.079
_refine_ls_abs_structure_details
;
In the absence of significant anomalous scattering effects, the absolute
structure is not determined. Friedel pairs have *not* been merged.
;
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.999
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     208
_refine_ls_number_reflns         3867
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.999
_refine_ls_R_factor_all          0.0745
_refine_ls_R_factor_gt           0.0643
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1018P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1524
_refine_ls_wR_factor_ref         0.1555
_reflns_number_gt                3224
_reflns_number_total             3867
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            c2ob26333e.txt
_cod_data_source_block           cam49
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               7152690