10.1002/cctc.202001139
ChemCatChem
Rf 0.90 (petroleum ether/Et2O, 9:1); [α]ꢀꢁꢄ +17.0 (c 0.10, CHCl3); IR νmax/cm-1 2957, 2926, 2854, 2358, 2312, 1722,
1633, 1257, 1177, 1038, 911,835, 806, 774; 1H NMR (400 MHz, CDCl3) δ 6.20 (ddd, J = 11.6, 7.9, 7.1 Hz, 1H), 5.81
(dt, J = 11.6, 1.8 Hz, 1H), 5.68 (ddd, J = 17.3, 10.3, 7.5 Hz, 1H), 4.99–4.91 (m, 2H), 4.16 (q, J = 7.1 Hz, 2H), 3.78–3.71
(m, 1H), 2.67–2.53 (m, 2H), 2.36–2.23 (m, 1H), 1.73–1.62 (m, 1H), 1.49–1.31 (m, 4H), 1.29 (t, J = 7.1 Hz, 3H), 0.98
13
(d, J = 6.8 Hz, 3H), 0.90 (d, J = 6.7 Hz, 3H), 0.88 (s, 9H), 0.05 (s, 3H), 0.04 (s, 3H); C NMR (100 MHz, CDCl3) δ
166.6, 149.1, 144.7, 120.8, 112.9, 68.9, 59.9, 45.2, 44.6, 36.4, 34.2, 30.0, 26.1, 21.3, 20.1, 18.2, 14.4, −3.8, −4.0; HRMS
(ESI+) [M + Na]+ m/z: calcd. for C21H40NaO3Si+ 391.2639, found: 391.2649.
(5S,7S,9S,Z)-7-((tert-Butyldimethylsilyl)oxy)-5,9-dimethylundeca-2,10-dienoic acid (23)
To a stirred solution of 48 (38.0 mg, 103 µmol) in THF/EtOH/H2O (1.50 mL, 1:1:1 v/v) at rt was added LiOH·H2O
(43.0 mg, 1.02 mmol). The reaction mixture was stirred at 50 °C for 3 h. The reaction was then cooled to rt and quenched
with sat. aq. NH4Cl (10.00 mL). The reaction mixture was extracted with EtOAc (3 × 5.00 mL) and the combined
organic extracts were dried over anhydrous Na2SO4, filtered and concentrated in vacuo. Purification by column
chromatography (petroleum ether/Et2O, 1:1) afforded title compound 23 (31.0 mg, 88%) as a yellow oil.
Rf 0.77 (petroleum ether/Et2O, 1:1); [α]ꢀꢁꢄ +22.0 (c 0.05, CHCl3); IR νmax/cm-1 2956, 2927, 2856, 2344, 2310, 1695,
1640, 1462, 1250, 1053, 912, 835,775; 1H NMR (400 MHz, CDCl3) δ 6.34 (dt, J = 11.7, 7.5 Hz, 1H), 5.85 (d, J = 11.6
Hz, 1H), 5.68 (ddd, J = 17.3, 10.3, 7.6 Hz, 1H), 5.00–4.91 (m, 2H), 3.79–3.73 (m, 1H), 2.64–2.59 (m, 2H), 2.37–2.24
(m, 1H), 1.75–1.66 (m, 1H), 1.49–1.31 (m, 2H), 0.99 (d, J = 6.8 Hz, 3H), 0.91 (d, J = 6.7 Hz, 3H), 0.88 (s, 9H), 0.05 (s,
3H), 0.04 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 171.2, 152.0, 144.7, 120.0, 112.9, 68.9, 45.2, 44.6, 36.5, 34.2, 30.0,
26.1, 21.3, 20.1, 18.2, −3.8, −4.0; HRMS (ESI+) [M + Na]+ m/z: calcd. for C19H36NaO3Si+ 363.2326, found: 363.2326.
(2R,3R)-1-((4-Methoxybenzyl)oxy)-3-methylpent-4-en-2-yl (5S,7S,9S,Z)-7-((tert-butyldimethylsilyl)oxy)-5,9-
dimethylundeca-2,10-dienoate (22) and (2R,3R)-1-((4-methoxybenzyl)oxy)-3-methylpent-4-en-2-yl (5S,7S,9S,E)-7-
((tert-butyldimethylsilyl)oxy)-5,9-dimethylundeca-2,10-dienoate (37)
To a stirred solution of 23 (30.0 mg, 88.1 µmol) in toluene (1.00 mL) at rt was added 2,4,6-trichlorobenzoyl chloride
(15.0 µL, 95.9 µmol) followed by NiPr2Et (70.0 µL, 402 µmol) and DMAP (5.50 mg, 49.0 µmol). The reaction mixture
was stirred at rt for 5 min, then a solution of 5 (20.0 mg, 84.6 µmol) in toluene (0.50 mL) was added. The reaction
mixture was stirred at 80 °C for 18 h then cooled to rt. The reaction was quenched with sat. aq. NaHCO3 (5.00 mL) and
the separated aqueous layer was extracted with EtOAc (3 × 3.00 mL). The combined organic extracts were dried over
anhydrous Na2SO4, filtered and concentrated in vacuo. Purification by flash chromatography (petroleum ether/EtOAc,
19:1) afforded desired compound 22 (9.00 mg, 19%) as a colourless oil and E isomer 37 (28.0 mg, 59%) as a colourless
oil.
Characterisation of 22:
Rf 0.66 (petroleum ether/EtOAc, 9:1); [α]ꢀꢁꢄ +18.0 (c 0.10, CHCl3); IR νmax/cm-1 2957, 2927, 2856, 1722, 1641, 1514,
1463, 1416, 1376, 1249, 1172, 1101, 1039, 913, 805, 774; 1H NMR (400 MHz, CDCl3) δ 7.23 (d, J = 8.7 Hz, 2H), 6.86
(d, J = 8.7 Hz, 2H), 6.20 (ddd, J = 11.6, 6.8, 8.0 Hz, 1H), 5.84 (dt, J = 11.6, 1.8 Hz, 1H), 5.78–5.63 (m, 2H), 5.07–4.91
(m, 3H), 4.45 (ABq, ΔνAB = 25.0 Hz, JAB = 11.7 Hz, 2H), 3.80 (s, 3H), 3.78–3.71 (m, 1H), 3.51 (ABX, ΔνAB = 10.0 Hz,
JAB = 10.5 Hz, JAX = 5.7 Hz, JBX = 4.7 Hz, 2H), 2.69–2.51 (m, 3H), 2.37–2.26 (m, 1H), 1.72–1.62 (m, 1H), 1.49–1.28
(m, 4H), 1.00 (d, J = 7.0 Hz, 3H), 0.98 (d, J = 6.8 Hz, 3H), 0.90–0.87 (m, 12H), 0.05 (s, 3H), 0.04 (s, 3H); 13C NMR
(100 MHz, CDCl3) δ 166.1, 159.4, 149.4, 144.7, 139.4, 130.4, 129.4, 120.8, 115.8, 113.9, 112.9, 74.8, 72.9, 69.3, 68.9,
55.4, 45.3, 44.6, 39.1, 36.5, 34.2, 30.0, 26.1, 21.3, 20.0, 18.2, 16.5, −3.8, −4.0; HRMS (ESI+) [M + Na]+ m/z: calcd. for
C33H54NaO5Si+ 581.3633, found: 581.3626.
Characterisation of 37:
Rf 0.59 (petroleum ether/EtOAc, 9:1); [α]ꢀꢁꢄ +4.0 (c 0.10, CHCl3); IR νmax/cm-1 2957, 2929, 2857, 1722, 1654, 1614,
1514, 1463, 1361, 1249, 1172, 1102, 1039, 913, 835, 774; 1H NMR (400 MHz, CDCl3) δ 7.23 (d, J = 8.7 Hz, 2H), 6.97–
16
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