Formal total synthesis of triptolide.
Miller, Natalie A; Willis, Anthony C; Sherburn, Michael S; Chemical communications (Cambridge, England)  (2008) 1226–1228; doi:10.1039/b718754h

data_7102941
_publ_section_title
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 Formal total synthesis of triptolide.
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_journal_issue                   10
_journal_name_full               'Chemical communications (Cambridge, England)'
_journal_page_first              1226
_journal_page_last               1228
_journal_paper_doi               10.1039/b718754h
_journal_year                    2008
_chemical_absolute_configuration unk
_chemical_compound_source        local
_chemical_formula_moiety         'C20 H26 O4'
_chemical_formula_sum            'C20 H26 O4'
_chemical_formula_weight         330.42
_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
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   6.8313(1)
_cell_length_b                   10.1677(2)
_cell_length_c                   25.1585(4)
_cell_measurement_reflns_used    17752
_cell_measurement_temperature    200
_cell_measurement_theta_max      25
_cell_measurement_theta_min      3
_cell_volume                     1747.47(5)
_computing_cell_refinement       'Denzo/Scalepack '
_computing_data_collection       'COLLECT (Nonius BV, 1997)'
_computing_data_reduction        'Denzo/Scalepack (Otwinowski & Minor, 1996)'
_computing_molecular_graphics
;
ORTEP-II (Johnson 1976) in teXsan (MSC, 1992-1997)
;
_computing_publication_material  'CRYSTALS '
_computing_structure_refinement  'CRYSTALS (Watkin et al 2003)'
_computing_structure_solution    'SIR92 (Altomare et al, 1994)'
_diffrn_ambient_temperature      200
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Nonius KappaCCD'
_diffrn_measurement_method       ' \f and \w scans with CCD '
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.037
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       29
_diffrn_reflns_limit_l_min       -29
_diffrn_reflns_number            18576
_diffrn_reflns_theta_full        25.020
_diffrn_reflns_theta_max         25.0
_diffrn_reflns_theta_min         2.576
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.086
_exptl_absorpt_correction_T_max  0.995
_exptl_absorpt_correction_T_min  0.978
_exptl_absorpt_correction_type   integration
_exptl_absorpt_process_details
;
via Gaussian method (Coppens, 1970) implemented in maXus (2000)
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.256
_exptl_crystal_density_meas      ?
_exptl_crystal_description       plate
_exptl_crystal_F_000             712
_exptl_crystal_size_max          0.36
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.06
_refine_diff_density_max         0.14
_refine_diff_density_min         -0.15
_refine_ls_abs_structure_details
;
The crystal comes from racemic solution.
The absolute configuration could not be determined.
The chirality of the molecule has been chosen arbitrarily.
;
_refine_ls_extinction_method     None
_refine_ls_goodness_of_fit_ref   1.0504
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     220
_refine_ls_number_reflns         1522
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.0410
_refine_ls_R_factor_gt           0.0336
_refine_ls_shift/su_max          0.000230
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;
Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982)
[weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)]
where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax
Method = Robust Weighting (Prince, 1982)
W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^
A~i~ are:
0.929 0.719 0.555
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0451
_refine_ls_wR_factor_gt          0.0403
_refine_ls_wR_factor_ref         0.0403
_reflns_limit_h_max              8
_reflns_limit_h_min              0
_reflns_limit_k_max              12
_reflns_limit_k_min              0
_reflns_limit_l_max              29
_reflns_limit_l_min              0
_reflns_number_gt                1522
_reflns_number_total             1806
_reflns_threshold_expression     I>1.5\s(I)
_cod_data_source_file            b718754h.txt
_cod_data_source_block           she0601
_cod_depositor_comments
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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_enum 1527 2010-12-29 10:47:43Z saulius 
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_cod_original_sg_symbol_H-M      'P 21 21 21 '
_cod_database_code               7102941