The Journal of Organic Chemistry
Page 14 of 20
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(2Z,5S,7S,8E,10E)-Methyl
7-[(tert-butyldimethylsilyl)oxy]-12-hydroxy-5-methoxy-2,9-
dimethyldodeca-2,8,10-trienoate (12). A solution of vinyl stannane 11 (929 mg, 1.44 mmol, 1
equiv) and (E)ꢀ3ꢀiodopropꢀ2ꢀenꢀ1ꢀol (794 mg, 4.32 mmol, 3 equiv) in freshly distilled DMF
was degassed for 45 min. The degassed solution was then added to a round bottom flask
containing flame dried [Ph2PO2][NBu4] (1.32 g, 2.88 mmol, 2 equiv). Copperꢀthiophene
carboxylate (CuTC) (549 mg, 2.88 mmol, 2 equiv) was then added, followed by Pd(PPh3)4
(166.3 mg, 0.144 mmol, 10 mol %) and the mixture was stirred at room temperature for 2 h.
The reaction was quenched with water and diluted with Et2O. The phases were separated and
the aqueous layer was extracted three times with Et2O. The combined organic layers were
washed with brine, dried over anhydrous Na2SO4, filtered and concentrated under vacuum.
The crude mixture was purified by silica gel column chromatography to yield the triene 12 as
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a yellow oil (502 mg, 85%).Error! Bookmark not defined.
[
α
]2ꢀ0 + 2.8 (c = 1.0, CHCl3); IR (neat)
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1716, 1459, 1435, 1362, 1249, 1217, 1137, 1083, 1064 cmꢀ1; HꢀNMR (400 MHz, CDCl3)
δ
(ppm) 6.25 (dt, J = 15.7, 1.5 Hz, 1H), 6.0 (ddd, J = 7.6, 6.4, 1.7 Hz, 1H), 5.79 (dt, J = 15.6,
6.0 Hz, 1H), 5.37 (d, J = 9.5 Hz, 1H), 4.62 (ddd, J = 9.0, 7.3, 6.3 Hz, 1H), 4.22 (dd, J = 6.0,
1.5 Hz, 2H), 3.72 (s, 3H), 3.27 (s, 3H), 3.27ꢀ3.22 (m, 1H), 2.82ꢀ2.65 (m, 2H), 1.91 (q, J =1.6
Hz, 3H), 1.85 (dd, J = 13.8, 7.1 Hz, 1H), 1.76 (d, J = 1.2 Hz, 3H) 1.45 (ddd, J = 13.8, 7.3, 5.1
Hz, 1H), 0.85 (s, 9H), 0.02 (s, 3H), ꢀ0.02 (s, 3H); 13CꢀNMR (100 MHz, CDCl3)
δ
(ppm)
168.2, 138.8, 136.0 (2C), 132.2, 128.5, 127.1, 77.0, 66.7, 63.8, 56.0, 51.3, 42.4, 32.6, 25.8
(3C), 20.8, 18.1, 12.8,
−4.2, −
4.8; HRMS (ESI) m/z calculated for (C22H40O5Si)Na+:
435.2537, found: 435.2539. The OH group was not detected in the 1HꢀNMR.
(1R,2R,4aR,5S,7S,8aR)-Methyl 5-[(tert-butyldimethylsilyl)oxy]-2-(hydroxymethyl)-7-methoxy
-1,4-dimethyl-1,2,4a,5,6,7,8,8a-octahydronaphthalene-1-carboxylate
(exoꢀ13)
and
(3aS,5aS,6S,8S,9aR,9bR)-6-[(tert-butyldimethylsilyl)oxy]-8-methoxy-5,9b-dimethyl-
3,3a,5a,6,7,8,9,9a-octahydronaphtho[1,2-c]furan-1(9bH)-one (endo-14). In a microwave vial
was added triene 12 (74.5 mg, 0.18 mmol, 1 equiv), followed by toluene (16 mL), argon was
then bubbled into the solution for 0.5 h. The vial was then fitted with a cap and heated at
210 °C in a microwave reactor for 3.5 h. The reaction was then concentrated under vacuum
and purified by silica gel column chromatography (PE/EtOAc = 8:2 to 7:3) to afford the exoꢀ
decalin 13 as a colorless oil (45 mg, 60%) along with a minor product, the endoꢀdecalin 14
(yellow oil, 6 mg, 8%). Major Product (exoꢀ13): [
α
]2ꢀ0 – 9.7 (c = 1.0, CHCl3); IR (neat) 1726,
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1462, 1377, 1255, 1209, 1146, 1118, 1078, 1006, 774, 736, 702, 669, 595 cmꢀ1; HꢀNMR
(400 MHz, benzeneꢀd6)
δ (ppm) 5.40 (dt, J = 5.8, 1.8, 1H), 3.57 (ddd, J =10.8, 9.5, 4.3 Hz,
1H), 3.48 (dd, J = 11.2, 4.6, 1H), 3.40 (dd, J = 11.2, 5.5 Hz, 1H), 3.24 (s, 3H), 3.19 (s, 3H),
2.98 (tt, J = 11.0, 4.4 Hz, 1H), 2.84ꢀ2.77 (m, 1H), 2.50ꢀ2.44 (m, 1H), 2.41 (t, J = 10.8 Hz,
1H), 2.26 (ddt, J = 12.2, 4.5, 2.2 Hz, 1H), 2.04 (s, 3H), 1.78 (q, J =12.1 Hz, 1H), 1.65 (q, J =
11.5 Hz, 1H), 1.48 (ddd, J = 12.7, 10.2, 2.3, 1H), 1.19 (s, 3H), 0.94 (s, 9H), 0.07 (s, 6H); 13Cꢀ
NMR (100 MHz, benzeneꢀd6)
δ (ppm) 176.4, 140.2, 124.9, 77.5, 74.7, 62.6, 55.6, 51.2, 49.7,
47.2, 45.4, 44.1, 40.2, 32.4, 26.4 (3C), 25.1, 22.2, 18.3, –3.1, –3.7; HRMS (ESI) m/z
calculated for (C22H40O5Si)Na+: 435.2537, found: 435.2536. The OH group was not detected
in the 1HꢀNMR.
Minor product (lactone endoꢀ14) [
α
]2ꢀ0 – 32.0 (c = 0.8, CHCl3); IR (neat) 1767, 1725, 1453,
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1381, 1255, 1223, 1108, 1086, 1003 cmꢀ1; HꢀNMR (400 MHz, CDCl3)
δ (ppm) 5.35 (br s,
1H), 4.38 (dd, J = 10.0, 8.8 Hz, 1H), 3.81 (dd, J = 10.4, 8.9 Hz, 1H), 3.72ꢀ3.67 (m, 1H), 3.30
(s, 3H), 3.11 (tt, J = 11.0, 4.5 Hz, 1H), 2.77ꢀ2.72 (m, 1H), 2.55 (br s, 1H), 2.08ꢀ2.03 (m, 1H),
1.91 (s, 3H), 1.77ꢀ1.73 (m, 1H), 1.63 (ddd, J = 13.1, 3.7, 3.1 Hz, 1H), 1.47ꢀ1.37 (m, 1H), 1.31
(s, 3H), 1.28ꢀ1.22 (m, 1H), 0.90 (s, 9H), 0.08 (2s, 6H); 13CꢀNMR (100 MHz, CDCl3)
δ (ppm)
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