An organocatalytic asymmetric allylic alkylation allows enantioselective total synthesis of hydroxymetasequirin-a and metasequirin-B tetramethyl ether diacetates.
Wang, Pu-Sheng; Zhou, Xiao-Le; Gong, Liu-Zhu; Organic letters 16 (2014) 976–979; doi:10.1021/ol4037055

data_1513504
_publ_section_title
;
 An organocatalytic asymmetric allylic alkylation allows enantioselective
 total synthesis of hydroxymetasequirin-a and metasequirin-B tetramethyl
 ether diacetates.
;
_journal_issue                   3
_journal_name_full               'Organic letters'
_journal_page_first              976
_journal_page_last               979
_journal_paper_doi               10.1021/ol4037055
_journal_volume                  16
_journal_year                    2014
_chemical_formula_sum            'C25 H28 O9'
_chemical_formula_weight         472.47
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_atom_sites_solution_hydrogens   geom
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_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 93.9580(10)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   8.7966(3)
_cell_length_b                   8.4402(2)
_cell_length_c                   32.1945(9)
_cell_measurement_temperature    296(2)
_cell_volume                     2384.58(12)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
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_diffrn_reflns_limit_h_max       10
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_diffrn_reflns_limit_l_min       -38
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_exptl_absorpt_correction_T_min  0.9725
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.316
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1000
_exptl_crystal_size_max          0.28
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.17
_refine_diff_density_max         0.238
_refine_diff_density_min         -0.193
_refine_diff_density_rms         0.037
_refine_ls_extinction_coef       0.0037(9)
_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   0.994
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     308
_refine_ls_number_reflns         4198
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.994
_refine_ls_R_factor_all          0.0700
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_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^)+(0.0588P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1031
_refine_ls_wR_factor_ref         0.1151
_reflns_number_gt                2749
_reflns_number_total             4198
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol4037055_si_002.cif
_cod_data_source_block           z
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to
/usr/data/users/saulius/automatic-downloads/current/ACS/lib/dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 2281 2013-09-26 08:29:07Z andrius 
;
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               1513504