Compound 2d

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

Prepared according to general procedure 2 outlined for compound 2a from methyl 2-acetyl-2-(penta-3,4-dien-1-yl)hepta-5,6-dienoate 1d (33.2 mg, 0.134 mmol). After a reaction time of 30 h at –40 °C, the crude product was purified by careful column chromatography (hexane/EtOAc 98:2 to 95:5 to elute the product, then 80:20 to elute ligand 3f) to afford diastereopure 2d as a colorless oil (24.2 mg, 72%, er: 78:22). ¹H NMR (400 MHz, CDCl₃) δ5.81 (ddd, 1 H, J = 17.2, 10.3, 7.3 Hz, CH=CH₂), 5.13–4.99 (m, 3 H, CH=CH_cisH_trans + CH=CH_cisH_trans + CH=C=CH₂), 4.71–4.65 (m, 2 H, CH=C=CH₂), 3.74 (s, 3 H, CO₂CH₃), 3.56–3.53 (bs, 1 H, OH), 2.56–2.48 (m, 1 H, CHCH=CH₂), 2.44–2.35 (m, 1 H, CHCH₂CH_aH_bCCO₂CH₃), 2.00–1.83 (m, 4 H, CH₂CH=C=CH₂ + CH_aH_bCH₂CH=C=CH₂ + CHCH_aH_bCH₂CCO₂CH₃), 1.60–1.40 (m, 3 H, CH_aH_bCH₂CH=C=CH₂ + CHCH₂CH_aH_bCCO₂CH₃+ CHCH_aH_bCH₂CCO₂CH₃), 1.08 (s, 3 H, CH₃COH); ¹³C NMR (100 MHz, CDCl₃) δ208.3 (CH=C=CH₂), 177.7 (CO₂CH₃), 138.0 (CH=CH₂), 116.2 (CH=CH₂), 89.7 (CH=C=CH₂), 82.7 (COH), 75.6 (CH=C=CH₂), 58.8 (CCO₂CH₃), 53.1 (CHCH=CH₂), 52.2 (CO₂CH₃), 33.4 (CH₂CH₂CH=C=CH₂), 30.3 (CHCH₂CH₂CCO₂CH₃), 24.7 (CHCH₂CH₂CCO₂CH₃), 24.4 (CH₂CH=C=CH₂), 18.9 (CH₃COH); ); IR ν_max (neat/cm^-1): 3478, 2950, 2346, 1955, 1719, 1638, 1436, 1377, 1326, 1274, 1192, 1175, 1091, 996, 911, 843; HRMS (APCI) calcd for C₁₅H₂₃O₃, [M+H]⁺: 251.1642, found 251.1644. [α]²²_D = +16.5 (c = 0.23, CH₂Cl₂).

Enantiomeric purity of the product was determined by GC analysis (Chiraldex^® G-TA 30 m x 0.25 mm column, isothermal run at 120 °C, flow rate = 1.0 mL/min, retention time: 138.0 min (major), 140.2 min (minor); er: 78:22.