Strained to the limit: when a cyclobutyl moiety becomes a thermodynamic sink in a protolytic ring-opening of photogenerated oxetanes.
Valiulin, Roman A.; Arisco, Teresa M.; Kutateladze, Andrei G.; Organic letters 12 (2010) 3398–3401; doi:10.1021/ol101297b

data_1503094
_publ_section_title
;
 Strained to the limit: when a cyclobutyl moiety becomes a thermodynamic
 sink in a protolytic ring-opening of photogenerated oxetanes.
;
_journal_issue                   15
_journal_name_full               'Organic letters'
_journal_page_first              3398
_journal_page_last               3401
_journal_paper_doi               10.1021/ol101297b
_journal_volume                  12
_journal_year                    2010
_chemical_formula_moiety         'C18 H20 O2'
_chemical_formula_sum            'C18 H20 O2'
_chemical_formula_weight         268.35
_chemical_name_common            none
_chemical_name_systematic
;
1S(R), 2R(S), 4R(S), 5S(R), 8R(S), 9S(R), 11S(R), 12R(S)-
pentacyclo[10.2.2.2^5,8^.0^2,11^.0^4,9^]octadeca-6,13-diene-3,10-dione
;
_space_group_IT_number           14
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_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                 90.515(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   23.7529(9)
_cell_length_b                   6.5856(3)
_cell_length_c                   17.3617(7)
_cell_measurement_reflns_used    8277
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      25.36
_cell_measurement_theta_min      2.89
_cell_volume                     2715.73(19)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      296(2)
_diffrn_detector_area_resol_mean 8.33
_diffrn_measured_fraction_theta_full 0.976
_diffrn_measured_fraction_theta_max 0.976
_diffrn_measurement_device_type  'Bruker D8 APEX II Diffractometer'
_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  0.0277
_diffrn_reflns_av_sigmaI/netI    0.0278
_diffrn_reflns_limit_h_max       28
_diffrn_reflns_limit_h_min       -21
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            13270
_diffrn_reflns_theta_full        25.03
_diffrn_reflns_theta_max         25.03
_diffrn_reflns_theta_min         0.86
_exptl_absorpt_coefficient_mu    0.084
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.320
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             1164
_exptl_crystal_size_max          1.00
_exptl_crystal_size_mid          0.65
_exptl_crystal_size_min          0.45
_refine_diff_density_max         0.326
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_refine_ls_number_reflns         4675
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.043
_refine_ls_R_factor_all          0.0532
_refine_ls_R_factor_gt           0.0442
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0906P)^2^+0.7724P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1318
_refine_ls_wR_factor_ref         0.1423
_reflns_number_gt                3913
_reflns_number_total             4675
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol101297b_si_002.cif
_cod_data_source_block           222_da_adduct_2_photo_0ma
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
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 
;
_cod_original_sg_symbol_H-M      'P2(1)/c  '
_cod_database_code               1503094