Lewis acid catalyzed cascade annulation of alkynols with α-ketoesters: A facile access to γ-spiroketal-γ-lactones
Kontham, Ravindar; Kambale, Digambar Abasaheb; Thorat, Sagar Sudam; Pratapure, Madhukar Shivaji; Gonnade, Rajesh G.; Chem. Commun.  (2017) –; doi:10.1039/C7CC03668J

data_7120205
_publ_section_title
;
 Lewis acid catalyzed cascade annulation of alkynols with \a-ketoesters: A
 facile access to \g-spiroketal-\g-lactones
;
_journal_name_full               'Chem. Commun.'
_journal_paper_doi               10.1039/C7CC03668J
_journal_year                    2017
_chemical_formula_moiety         'C18 H20 O4'
_chemical_formula_sum            'C18 H20 O4'
_chemical_formula_weight         300.34
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2016-10-17 deposited with the CCDC.
2017-05-30 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   12.5888(15)
_cell_length_b                   19.163(3)
_cell_length_c                   6.1053(7)
_cell_measurement_reflns_used    1027
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      21.55
_cell_measurement_theta_min      3.41
_cell_volume                     1472.8(3)
_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-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_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  0.1148
_diffrn_reflns_av_unetI/netI     0.0859
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       23
_diffrn_reflns_limit_k_min       -23
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -7
_diffrn_reflns_number            18930
_diffrn_reflns_point_group_measured_fraction_full 0.993
_diffrn_reflns_point_group_measured_fraction_max 0.991
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         25.997
_diffrn_reflns_theta_min         1.936
_exptl_absorpt_coefficient_mu    0.095
_exptl_absorpt_correction_T_max  0.982
_exptl_absorpt_correction_T_min  0.967
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Bruker, 2006)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.354
_exptl_crystal_description       block
_exptl_crystal_F_000             640
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: dichloromethane-petroleum ether'
_exptl_crystal_size_max          0.360
_exptl_crystal_size_mid          0.240
_exptl_crystal_size_min          0.190
_refine_diff_density_max         0.354
_refine_diff_density_min         -0.400
_refine_diff_density_rms         0.083
_refine_ls_extinction_coef       0.011(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2014/7 (Sheldrick 2014'
_refine_ls_goodness_of_fit_ref   1.156
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     201
_refine_ls_number_reflns         2872
_refine_ls_number_restraints     97
_refine_ls_restrained_S_all      1.156
_refine_ls_R_factor_all          0.1019
_refine_ls_R_factor_gt           0.0858
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0466P)^2^+3.4405P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1674
_refine_ls_wR_factor_ref         0.1744
_reflns_Friedel_coverage         0.802
_reflns_Friedel_fraction_full    0.984
_reflns_Friedel_fraction_max     0.979
_reflns_number_gt                2445
_reflns_number_total             2872
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c7cc03668j2.cif
_cod_data_source_block           SAGAR_MSB129_090616
_cod_database_code               7120205
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.967
_shelx_estimated_absorpt_t_max   0.982
_shelx_res_checksum              75004
_shelx_hkl_checksum              55074