Cascade [1,3]-Sigmatropic Rearrangements of Ketene O,O-Acetals: Kinetic and DFT Level Mechanistic Studies
Perla Y. López-Camacho; Pedro Joseph-Nathan; Bárbara Gordillo-Román; Oscar R. Suárez-Castillo; Martha S. Morales-Ríos; Journal of Organic Chemistry 75 (2010) 1898–1910; doi:10.1021/jo902520z

data_4025302
_publ_section_title
;
 Cascade [1,3]-Sigmatropic Rearrangements of Ketene O,O-Acetals: Kinetic
 and DFT Level Mechanistic Studies
;
_journal_name_full               'Journal of Organic Chemistry'
_journal_page_first              1898
_journal_page_last               1910
_journal_paper_doi               10.1021/jo902520z
_journal_volume                  75
_journal_year                    2010
_chemical_formula_moiety         'C18 H20 N2 O4'
_chemical_formula_sum            'C18 H20 N2 O4'
_chemical_formula_weight         328.36
_chemical_melting_point          177.5(15)
_chemical_name_systematic
;
 Methyl 3-cyano-8b-tert-butyl-2-methoxy-3aH-furo[3,2-b]
indole-4(8bH)-carboxylate.
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yab'
_symmetry_space_group_name_H-M   'P 1 21/a 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                 115.70(1)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   12.831(2)
_cell_length_b                   10.528(2)
_cell_length_c                   14.230(2)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      15.24
_cell_measurement_theta_min      6.91
_cell_volume                     1732.1(5)
_computing_cell_refinement       'CAD4 Express (Enraf Nonius, 1994)'
_computing_data_collection       'CAD4 Express (Enraf Nonius, 1994)'
_computing_data_reduction        'XCAD4 (Harms & Wocadlo, 1995)'
_computing_molecular_graphics    'Ortep-3 for Windows (Farrugia, 1997)'
_computing_publication_material  'WinGX publication routines (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.968
_diffrn_measured_fraction_theta_max 0.968
_diffrn_measurement_device_type  'Enraf Nonius CAD4'
_diffrn_measurement_method       'non-profiled omega/2theta scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0001
_diffrn_reflns_av_sigmaI/netI    0.0140
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            2482
_diffrn_reflns_theta_full        59.95
_diffrn_reflns_theta_max         59.95
_diffrn_reflns_theta_min         5.44
_diffrn_standards_decay_%        2
_diffrn_standards_interval_count 90
_diffrn_standards_interval_time  2400
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    0.737
_exptl_absorpt_correction_T_max  0.9153
_exptl_absorpt_correction_T_min  0.4272
_exptl_absorpt_correction_type   refdelf
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.259
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             696
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.38
_exptl_crystal_size_min          0.34
_refine_diff_density_max         0.233
_refine_diff_density_min         -0.185
_refine_diff_density_rms         0.030
_refine_ls_extinction_coef       0.0008(3)
_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   1.107
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     222
_refine_ls_number_reflns         2482
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.107
_refine_ls_R_factor_all          0.0433
_refine_ls_R_factor_gt           0.0403
_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^)+(0.0538P)^2^+0.5257P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1112
_refine_ls_wR_factor_ref         0.1129
_reflns_number_gt                2292
_reflns_number_total             2482
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo902520z_si_002_4.cif
_cod_data_source_block           4e
_cod_depositor_comments
;
The following automatic conversions were performed:

'_chemical_melting_point' value '176-179' was changed to '177.5(15)'
- the average value was taken and precision was estimated.

Automatic conversion script
Id: cif_fix_values 1569 2011-02-09 13:29:24Z adriana 

The following automatic conversions were performed:

'_exptl_absorpt_correction_type' value 'RefDelf' changed to 'refdelf'
according to the built-in table from CIF Core dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1646 2011-03-28 12:23:43Z adriana 
;
_cod_original_cell_volume        1732.2(5)
_cod_database_code               4025302