Synthesis of functionalized γ-lactone via Sakurai exo-cyclization/rearrangement of 3,3-bis(silyl) enol ester with a tethered acetal.
Yin, Zhiping; Liu, Zengjin; Huang, Zhenggang; Chu, Yang; Chu, Zhiwen; Hu, Jia; Gao, Lu; Song, Zhenlei; Organic letters 17 (2015) 1553–1556; doi:10.1021/acs.orglett.5b00437

data_1554856
_publ_section_title
;
 Synthesis of functionalized \g-lactone via Sakurai
 exo-cyclization/rearrangement of 3,3-bis(silyl) enol ester with a
 tethered acetal.
;
_journal_issue                   6
_journal_name_full               'Organic letters'
_journal_page_first              1553
_journal_page_last               1556
_journal_paper_doi               10.1021/acs.orglett.5b00437
_journal_volume                  17
_journal_year                    2015
_chemical_formula_moiety         'C20 H26 N2 O8 Si'
_chemical_formula_sum            'C20 H26 N2 O8 Si'
_chemical_formula_weight         450.52
_space_group_crystal_system      monoclinic
_space_group_IT_number           15
_space_group_name_Hall           '-C 2yc'
_space_group_name_H-M_alt        'C 1 2/c 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_date             2015-02-26
_audit_creation_method
;
Olex2 1.2
(compiled 2015.01.26 svn.r3150 for OlexSys, GUI svn.r4998)
;
_cell_angle_alpha                90.00
_cell_angle_beta                 90.534(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   18.687(7)
_cell_length_b                   6.709(2)
_cell_length_c                   37.603(13)
_cell_measurement_reflns_used    2098
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      18.94
_cell_measurement_theta_min      2.43
_cell_volume                     4714(3)
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      296.15
_diffrn_measured_fraction_theta_full 0.991
_diffrn_measured_fraction_theta_max 0.991
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0670
_diffrn_reflns_av_unetI/netI     0.0682
_diffrn_reflns_limit_h_max       21
_diffrn_reflns_limit_h_min       -22
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       45
_diffrn_reflns_limit_l_min       -45
_diffrn_reflns_number            16208
_diffrn_reflns_theta_full        25.50
_diffrn_reflns_theta_max         25.50
_diffrn_reflns_theta_min         2.43
_diffrn_source                   'fine-focus sealed tube'
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.145
_exptl_absorpt_correction_T_max  0.9729
_exptl_absorpt_correction_T_min  0.9646
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            'clear light yellow'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_modifier   light
_exptl_crystal_colour_primary    yellow
_exptl_crystal_density_diffrn    1.269
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1904
_exptl_crystal_size_max          0.25
_exptl_crystal_size_mid          0.24
_exptl_crystal_size_min          0.19
_refine_diff_density_max         0.300
_refine_diff_density_min         -0.319
_refine_diff_density_rms         0.055
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.019
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     318
_refine_ls_number_reflns         4339
_refine_ls_number_restraints     60
_refine_ls_restrained_S_all      1.026
_refine_ls_R_factor_all          0.1503
_refine_ls_R_factor_gt           0.0814
_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^)+(0.0922P)^2^+13.0886P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2045
_refine_ls_wR_factor_ref         0.2506
_reflns_number_gt                2280
_reflns_number_total             4339
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol5b00437_si_002.cif
_cod_data_source_block           c2c
_cod_database_code               1554856
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups, All C(H,H,H,H,H,H) groups
2. Uiso/Uaniso restraints and constraints
Uanis(C20) \\sim Ueq, Uanis(C17) \\sim Ueq, Uanis(C18) \\sim Ueq, Uanis(C19)
\\sim Ueq, Uanis(C19') \\sim Ueq, Uanis(C16) \\sim Ueq, Uanis(C15) \\sim Ueq,
Uanis(C15') \\sim Ueq, Uanis(C17') \\sim Ueq, Uanis(C18') \\sim Ueq: with sigma
of 0.01 and sigma for terminal atoms of 0.02
3. Others
 Fixed Sof: H16D(0.5) H16E(0.5) H16F(0.5) H16A(0.5) H16B(0.5) H16C(0.5)
 H20D(0.5) H20E(0.5) H20F(0.5) H20A(0.5) H20B(0.5) H20C(0.5) C15(0.5) H15A(0.5)
 H15B(0.5) C17(0.4) H17A(0.4) H17B(0.4) C18(0.4) H18A(0.4) H18B(0.4) H18C(0.4)
 C19(0.5) H19A(0.5) H19B(0.5) C15'(0.5) H15C(0.5) H15D(0.5) C19'(0.5) H19C(0.5)
 H19D(0.5) C17'(0.6) H17C(0.6) H17D(0.6) C18'(0.6) H18D(0.6) H18E(0.6) H18F(0.6)
4.a Ternary CH refined with riding coordinates:
 C8(H8), C12(H12)
4.b Secondary CH2 refined with riding coordinates:
 C9(H9A,H9B), C10(H10A,H10B), C15(H15A,H15B), C17(H17A,H17B), C19(H19A,H19B),
 C15'(H15C,H15D), C19'(H19C,H19D), C17'(H17C,H17D)
4.c Me refined with riding coordinates:
 C16(H16D,H16E,H16F), C16(H16A,H16B,H16C), C20(H20D,H20E,H20F), C20(H20A,H20B,
 H20C)
4.d Aromatic/amide H refined with riding coordinates:
 C1(H1), C3(H3), C5(H5), C13(H13), C14(H14)
4.e Idealised Me refined as rotating group:
 C18(H18A,H18B,H18C), C18'(H18D,H18E,H18F)
;
_olex2_submission_special_instructions 'No special instructions were received'