Stereoselective formation of N-acyliminium ion via chiral N,O-acetal TMS ether and its application to the synthesis of beta-amino acids.
Shin, Dong-Yun; Jung, Jae-Kyung; Seo, Seung-Yong; Lee, Yong-Sil; Paek, Seung-Mann; Chung, Young Keun; Shin, Dong Mok; Suh, Young-Ger; Organic letters 5 (2003) 3635–3638; doi:10.1021/ol035289e

data_1507364
_publ_section_title
;
 Stereoselective formation of N-acyliminium ion via chiral N,O-acetal TMS
 ether and its application to the synthesis of beta-amino acids.
;
_journal_issue                   20
_journal_name_full               'Organic letters'
_journal_page_first              3635
_journal_page_last               3638
_journal_paper_doi               10.1021/ol035289e
_journal_volume                  5
_journal_year                    2003
_chemical_formula_sum            'C21 H27 N O3 Si'
_chemical_formula_weight         369.53
_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                   9.2287(3)
_cell_length_b                   9.9625(3)
_cell_length_c                   23.3118(6)
_cell_measurement_reflns_used    3867
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25.350
_cell_measurement_theta_min      0.998
_cell_volume                     2143.31(11)
_computing_cell_refinement       'HKL Scalepack (Otwinowski & Minor 1997)'
_computing_data_collection       'Collect (Nonius BV, 1997-2000)'
_computing_data_reduction
'HKL Denzo and Scalepack (Otwinowski & Minor 1997)'
_computing_molecular_graphics    'ORTEP 32'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector_area_resol_mean 9
_diffrn_measured_fraction_theta_full 0.993
_diffrn_measured_fraction_theta_max 0.993
_diffrn_measurement_device_type  KappaCCD
_diffrn_measurement_method       CCD
_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  0.0269
_diffrn_reflns_av_sigmaI/netI    0.0399
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       9
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       27
_diffrn_reflns_limit_l_min       -27
_diffrn_reflns_number            6910
_diffrn_reflns_theta_full        25.34
_diffrn_reflns_theta_max         25.34
_diffrn_reflns_theta_min         2.37
_exptl_absorpt_coefficient_mu    0.128
_exptl_crystal_colour            white
_exptl_crystal_density_diffrn    1.145
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             792
_exptl_crystal_size_max          0.5
_exptl_crystal_size_mid          0.5
_exptl_crystal_size_min          0.4
_refine_diff_density_max         0.149
_refine_diff_density_min         -0.167
_refine_diff_density_rms         0.041
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.00(19)
_refine_ls_extinction_coef       0.043(4)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.102
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     240
_refine_ls_number_reflns         3874
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.102
_refine_ls_R_factor_all          0.0855
_refine_ls_R_factor_gt           0.0522
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0525P)^2^+0.3692P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1128
_refine_ls_wR_factor_ref         0.1294
_reflns_number_gt                2745
_reflns_number_total             3874
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol035289esi20030712_120133.cif
_cod_data_source_block           or
_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      P212121
_cod_database_code               1507364