Compound 9-SS

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Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Et₃B (0.99 M in hexane, 650 µL, 0.644 mmol) was added to a solution of acyl telluride 1k (63.0 mg, 0.0859 mmol) and 1l (22.9 mg, 0.0429 mmol) in benzene (0.33 mL) and CH₂Cl₂ (0.33 mL) at room temperature. The reaction mixture was vigorously stirred under air for 20 min at room temperature. The reaction mixture was filtered through a pad of silica gel (10 g, hexane to EtOAc), and the eluent of EtOAc was concentrated. The residue was purified by PTLC (hexane/EtOAc 3/1) to afford fraction A (11.0 mg), fraction B (4.9 mg), fraction C (5.1 mg) and a diastereomeric mixture of dimer 2k (14.6 mg, 0.0146 mmol, 34% yield, αα : αβ : ββ = 34 : 54 : 12). The fraction A (11.0 mg) was further purified by PTLC (hexane/CH₂Cl₂/Et₂O 2/2/1) to afford 9-SS (5.7 mg, 0.0071 mmol). The fraction B (4.9 mg) was further purified by PTLC (hexane/ CH₂Cl₂/Et₂O 2/2/1) to afford 9-RS (2.7 mg, 0.0034 mmol). The fraction C (5.1 mg) was further purified by PTLC (hexane/ CH₂Cl₂/Et₂O) to afford 9-SR (1.8 mg, 0.0022 mmol) and 9-RR (0.60 mg, 0.00075 mmol). Combined yield of the four diastereomers of 9 was 32%, and the diastereomeric ratio was 9-SS: 9-RS: 9-SS: 9-RR = 53 : 25 : 16 : 6. colorless solid; mp 101-104 °C; [α]_D²⁰ = –10.9 (c 1.04, CHCl₃); IR (film) 2986, 2936, 1779, 1731, 1717, 1384, 1273, 1110, 1092, 1068 cm^-1; ¹H NMR (400 MHz, CDCl₃) δ 1.04 (3H, s, CH₃ of acetonide), 1.11 (3H, s, CH₃ of acetonide), 1.32 (3H, s, CH₃ of acetonide), 1.36 (3H, s, CH₃ of acetonide), 1.41 (3H, s, CH₃ of acetonide), 1.43 (3H, s, CH₃ of acetonide), 3.55 (3H, s, OCH₃), 3.95 (1H, dd, J = 8.2, 5.0 Hz, H11_A), 4.03-4.15 (3H, m, H9, 10, and 11_B), 4.25 (1H, dd, J = 6.0, 2.8 Hz, H8), 4.29 (1H, dd, J = 7.3, 6.9 Hz, H6), 4.42 (1H, dd, J = 7.3, 2.8 Hz, H7), 4.56 (1H, dd, J = 9.6, 6.9 Hz, H5), 4.59 (1H, dd, J = 10.1, 9.6 Hz, H4), 4.81 (1H, d, J = 8.2 Hz, H1), 5.49 (1H, dd, J = 9.6, 8.2 Hz, H2), 6.37 (1H, dd, J = 10.1, 9.6 Hz, H3), 7.26 (2H, m, aromatic), 7.37 (2H, m, aromatic), 7.42 (1H, m, aromatic), 7.50 (1H, m, aromatic), 7.62-7.74 (3H, m, aromatic), 7.78 (2H, m, aromatic), 7.85 (1H, m, aromatic), 7.96 (2H, m, aromatic); ¹³C NMR (100 MHz, CDCl₃) δ 25.2, 26.4, 26.5, 26.76, 26.84, 27.2, 54.1, 57.2, 67.5, 70.3, 71.7, 72.4, 76.8, 77.5, 79.7, 80.4, 102.1, 109.4, 109.8, 110.3, 123.2, 123.3, 128.27 (2C), 128.30 (2C), 128.7, 129.3, 129.8 (2C), 129.9 (2C), 131.7, 132.0, 133.2 (2C), 133.9, 134.0, 165.3, 165.6, 167.6, 168.6 (one peak was overlapped with the solvent peaks); HRMS (ESI) calcd for C₄₃H₄₇NO₁₄Na [M+Na]⁺ 824.2889, found 824.2879.