A formal synthesis of the C1-C9 fragment of amphidinolide C employing the Tamaru reaction.
Paudyal, Mahesh P.; Rath, Nigam P.; Spilling, Christopher D.; Organic letters 12 (2010) 2954–2957; doi:10.1021/ol100959a

data_1503024
_publ_section_title
;
 A formal synthesis of the C1-C9 fragment of amphidinolide C employing the
 Tamaru reaction.
;
_journal_issue                   13
_journal_name_full               'Organic letters'
_journal_page_first              2954
_journal_page_last               2957
_journal_paper_doi               10.1021/ol100959a
_journal_volume                  12
_journal_year                    2010
_chemical_absolute_configuration ad
_chemical_formula_sum            'C21 H46 O4 Si2'
_chemical_formula_weight         418.76
_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                   6.8545(19)
_cell_length_b                   15.086(4)
_cell_length_c                   25.353(7)
_cell_measurement_reflns_used    3685
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      18.14
_cell_measurement_theta_min      2.70
_cell_volume                     2621.7(12)
_computing_cell_refinement       'Bruker-Apex II (Bruker, 2006)'
_computing_data_collection       'Bruker-Apex II (Bruker, 2006)'
_computing_data_reduction        'Bruker-SAINT   (Bruker, 2006)'
_computing_molecular_graphics    'Bruker-SHELXTL (Sheldrick, G.M., 2008)'
_computing_publication_material  'Bruker-SHELXTL (Sheldrick, G.M., 2008)'
_computing_structure_refinement  'Bruker-SHELXTL (Sheldrick, G.M., 2008)'
_computing_structure_solution    'Bruker-SHELXTL (Sheldrick, G.M., 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.984
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w 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  0.1244
_diffrn_reflns_av_sigmaI/netI    0.1243
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       18
_diffrn_reflns_limit_k_min       -18
_diffrn_reflns_limit_l_max       29
_diffrn_reflns_limit_l_min       -30
_diffrn_reflns_number            32379
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.46
_diffrn_reflns_theta_min         2.76
_exptl_absorpt_coefficient_mu    0.156
_exptl_absorpt_correction_T_max  0.9938
_exptl_absorpt_correction_T_min  0.9290
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'sadabs v2008/1'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.061
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             928
_exptl_crystal_size_max          0.48
_exptl_crystal_size_mid          0.12
_exptl_crystal_size_min          0.04
_refine_diff_density_max         0.294
_refine_diff_density_min         -0.273
_refine_diff_density_rms         0.057
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.3(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    noref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     281
_refine_ls_number_reflns         4789
_refine_ls_number_restraints     12
_refine_ls_restrained_S_all      1.023
_refine_ls_R_factor_all          0.1681
_refine_ls_R_factor_gt           0.0772
_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^)+(0.1001P)^2^+0.9149P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1759
_refine_ls_wR_factor_ref         0.2151
_reflns_number_gt                2430
_reflns_number_total             4789
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol100959a_si_002.cif
_cod_data_source_block           s15308
_cod_depositor_comments
;
The original CIF contained some information in plain text format that 
was 'glued' to  the value of '_refine_diff_density_rms' tag upon deposition.
The information was removed and stored here for further investigation. The 
following lines were extracted (delimited by #--):
We are aware of the level A warnings in the checkcif report. Several crystals 
were tried before this particular crystal was chosen for data collection. The 
data are very weak (mean I/sigma drops off rapidly beyond 1.1 \%A resolution 
and falls below 2 beyond (1.0 \%A) and of poor quality. The structure is 
disordered over two sets of atoms in two different places in the molecule. 
Several models using various sets of geometrical restraints were tried and the 
best model was used for resolving these disorders. The reported level A alerts 
are related to the disorder part of the molecule.
Antanas Vaitkus,
2015-03-01

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 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'NO' was changed to '?' - the
value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 
;
_cod_original_cell_volume        2621.6(12)
_cod_original_sg_symbol_H-M      P2~1~2~1~2~1~
_cod_database_code               1503024