Syntheses of Combretastatins D-1, D-2, and D-4 via Ring Contraction by Flash Vacuum Pyrolysis.
Harras, Marina; Milius, Wolfgang; Aitken, R. Alan; Schobert, Rainer; The Journal of organic chemistry 82 (2017) 579–587; doi:10.1021/acs.joc.6b02586

data_4032080
_publ_section_title
;
 Syntheses of Combretastatins D-1, D-2, and D-4 via Ring Contraction by
 Flash Vacuum Pyrolysis.
;
_journal_issue                   1
_journal_name_full               'The Journal of organic chemistry'
_journal_page_first              579
_journal_page_last               587
_journal_paper_doi               10.1021/acs.joc.6b02586
_journal_volume                  82
_journal_year                    2017
_chemical_formula_sum            'C18 H18 O2'
_chemical_formula_weight         266.32
_space_group_IT_number           14
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 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                 112.62(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   8.4129(17)
_cell_length_b                   18.533(4)
_cell_length_c                   9.925(2)
_cell_measurement_temperature    293(2)
_cell_volume                     1428.4(6)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.932
_diffrn_measured_fraction_theta_max 0.932
_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  0.2101
_diffrn_reflns_av_sigmaI/netI    0.2257
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       -22
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            10498
_diffrn_reflns_theta_full        26.12
_diffrn_reflns_theta_max         26.12
_diffrn_reflns_theta_min         2.20
_exptl_absorpt_coefficient_mu    0.079
_exptl_crystal_density_diffrn    1.238
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             568
_refine_diff_density_max         0.183
_refine_diff_density_min         -0.159
_refine_diff_density_rms         0.049
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.608
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     181
_refine_ls_number_reflns         2652
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.608
_refine_ls_R_factor_all          0.2144
_refine_ls_R_factor_gt           0.0540
_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^)+(0.0369P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0990
_refine_ls_wR_factor_ref         0.1358
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_reflns_number_total             2652
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo6b02586_si_001.cif
_cod_data_source_block           mh_1
_cod_depositor_comments          'Adding full bibliography for 4032080.cif.'
_cod_original_cell_volume        1428.4(5)
_cod_database_code               4032080