1544
W. H. Miles et al.
PAPER
cis-5-(Methylethyl)-7-(4-methylphenyl)-4,5-dihydro-7H-fura-
no[2,3,-c]pyran (2c)
(dd, 1 H, J = 3.7, 15.4 Hz), 2.34 (ddd, 1 H, J = 1.5, 9.2, 15.4 Hz),
1.2–1.8 (m, 22 H), 0.92 (t, 3 H, J = 7.1 Hz), 0.87 (t, 3 H, J = 6.6 Hz).
IR (film): 2960, 2872, 1606, 1515, 1469, 1370, 1133, 1058, 884,
730 cm–1.
cis-7-(tert-Butyl)-5-nonyl-4,5-dihydro-7H-furano[2,3-c]pyran
(2f)
1H NMR (400 MHz, CDCl3): = 7.27 (d, 2 H, J = 8.0 Hz), 7.22 (dd,
1 H, J = 0.7, 1.8 Hz), 7.16 (d, 2 H, J = 7.7 Hz), 6.26 (d, 1 H, J = 1.8
Hz), 5.56 (br s, 1 H), 3.49 (m, 1 H), 2.60 (ddd, 1 H, J = 2.8, 10.4,
15.4 Hz), 2.51 (ddd, 1 H, J = 2.2, 3.3, 15.4 Hz), 2.34 (s, 3 H), 1.89
(app. octet, 1 H, J = 6.7 Hz), 1.03 (d, 3 H, J = 6.6 Hz), 0.98 (d, 3 H,
J = 6.6 Hz).
IR (film): 2926, 2855, 1502, 1465, 1365, 1138, 1074, 723 cm–1.
1H NMR (400 MHz, CDCl3): = 7.26 (m, 1 H), 6.21 (d, 1 H, J = 1.8
Hz), 4.19 (m, 1 H), 3.47 (m, 1 H), 2.30–2.39 (m, 2 H), 1.25–1.70 (m,
16 H), 0.99 (s, 9 H), 0.88 (t, 3 H, J = 6.8 Hz).
13C NMR (100 MHz, CDCl3): = 151.2, 140.6, 117.1, 109.8, 81.4,
75.0, 35.7, 35.4, 31.9, 29.7, 29.6 (3 C), 29.3, 25.8, 22.7, 14.1.
13C NMR (100 MHz, CDCl3): = 150.3, 141.5, 138.0, 136.2, 129.1,
127.7, 115.9, 110.0, 81.0, 76.3, 32.7, 26.2, 21.2, 19.1, 18.2.
Anal. Calcd for C20H34O2 (306.5): C, 78.38; H, 11.18. Found: C,
78.41; H, 11.13.
Anal. Calcd for C17H20O2 (256.4): C, 79.65; H, 7.86. Found: C,
79.46; H, 7.98.
7,7-Dimethyl-5-nonyl-4,5-dihydro-7H-furano[2,3-c]pyran (2g)
IR (film): 2921, 2857, 1504, 1466, 1377, 1287, 1156, 1095, 726
cm–1.
cis-7-(Methylethyl)-5-nonyl-4,5-dihydro-7H-furano[2,3-c]pyr-
an (2d)
Flash chromatography of the crude product gave pure 2d (78%) and
a mixture of 2d and the trans-isomer of 2d (7%). Pure trans-isomer
of 2d was isolated by flash chromatography of the enriched fraction.
IR (film): 2922, 2855, 1502, 1466, 1385, 1142, 1068, 722 cm–1.
1H NMR (400 MHz, CDCl3): = 7.23 (d, 1 H, J = 1.8 Hz), 6.17 (d,
1 H, J = 1.8 Hz), 3.73 (m, 1 H), 2.37 (dd, 1 H, J = 3.8, 15.3 Hz),
2.34 (d, 1 H, J = 9.9, 15.4 Hz), 1.25–1.70 (m, 16 H), 1.46 (s, 3 H),
1.43 (s, 3 H), 0.87 (t, 3 H, J = 6.8 Hz).
1H NMR (400 MHz, CDCl3): = 7.26 (dd, 1 H, J = 0.7, 1.8 Hz),
6.21 (d, 1 H, J = 1.8 Hz), 4.43 (m, 1 H), 3.52 (m, 1 H), 2.31–2.42
(m, 2 H), 2.12 (d sept, 1 H, J = 3.9, 6.9 Hz), 1.20–1.70 (m, 16 H),
1.01 (d, 3 H, J = 7.0 Hz), 0.89 (d, 3 H, J = 7.0 Hz), 0.88 (t, 3 H,
J = 7.0 Hz).
13C NMR (100 MHz, CDCl3): = 154.8, 140.6, 113.3, 109.8, 72.7,
70.1, 35.7, 31.9, 29.8, 29.6 (3 C), 29.3, 28.0, 25.8, 25.1, 22.7, 14.1.
Anal. Calcd for C18H30O2 (278.4): C, 77.65; H, 10.86. Found: C,
77.69; H, 11.06.
13C NMR (100 MHz, CDCl3): = 151.1, 140.8, 116.2, 109.8, 78.0,
75.1, 35.7, 31.9, 31.7, 29.7 (2 C), 29.6, 29.5, 29.4, 25.8, 22.7, 18.1,
17.0, 14.1.
cis-7-(Methylethyl)-5-(4-methylphenyl)-4,5-dihydro-7H-fura-
no[2,3-c]pyran (2h)
IR (film): 2963, 2923, 1516, 1502, 1460, 1367, 1134, 1067, 815,
725 cm–1.
Anal. Calcd for C19H32O2 (292.5): C, 78.02; H, 11.03. Found: C,
78.00; H, 11.25.
1H NMR (400 MHz, CDCl3): = 7.32 (m, 3 H), 7.17 (d, 2 H, J = 7.7
Hz), 6.26 (d, 1 H, J = 1.5 Hz), 4.68 (m, 1 H), 4.62 (dd, 1 H, J = 5.7,
8.2 Hz), 2.62–2.72 (m, 2 H), 2.35 (s, 3 H), 2.23 (d sept, 1 H, J = 3.4,
7.0 Hz), 1.07 (d, 3 H, J = 7.0 Hz), 0.95 (d, 3 H, J = 7.0 Hz).
13C NMR (100 MHz, CDCl3): = 150.7, 141.1, 139.6, 137.0, 128.9,
125.7, 116.4, 109.7, 78.3, 76.3, 31.9, 31.7, 21.2, 18.2, 16.8.
trans-7-(Methylethyl)-5-nonyl-4,5-dihydro-7H-furano[2,3-
c]pyran (trans-Isomer of 2d)
IR (film): 2920, 2855, 1502, 1467, 1385, 1141, 1059, 723 cm–1.
1H NMR (400 MHz, CDCl3): = 7.28 (d, 1 H, J = 1.5 Hz), 6.22 (d,
1 H, J = 1.2 Hz), 4.23 (d, 1 H, J = 8.1 Hz), 3.82 (m, 1 H), 2.50 (dd,
1 H, J = 3.7, 14.7 Hz), 2.32 (dd, 1 H, J = 8.7, 14.7 Hz), 2.12 (app.
octet, 1 H, J = 7.0 Hz),), 1.20–1.70 (m, 16 H), 1.05 (d, 3 H, J = 6.6
Hz), 1.03 (d, 3 H, J = 6.6 Hz), 0.88 (t, 3 H, J = 6.8 Hz).
13C NMR (100 MHz, CDCl3): = 150.9, 141.0, 114.8, 109.7, 76.6,
69.9, 35.2, 31.9, 31.8, 29.7 (2 C), 29.6, 29.5 (2 C), 26.2, 22.7, 19.2,
18.6, 14.1.
Anal. Calcd for C17H20O2 (256.4): C, 79.65; H, 7.86. Found: C,
79.73; H, 7.96.
cis-7-Butyl-5-(4-methylphenyl)-4,5-dihydro-7H-furano[2,3-
c]pyran (2i)
IR (film): 2929, 2860, 1517, 1503, 1458, 1136, 1078, 726 cm–1.
1H NMR (400 MHz, CDCl3): = 7.37 (d, 2 H, J = 8.0 Hz), 7.34 (d,
1 H, J = 1.1 Hz), 7.21 (d, 2 H, J = 8.0 Hz), 6.30 (d, 1 H, J = 1.5 Hz),
4.85 (m, 1 H), 4.68 (dd, 1 H, J = 4.6, 9.4 Hz), 2.68–2.82 (m, 2 H),
2.39 (s, 3 H), 2.01 (m, 1 H), 1.83 (m, 1 H), 1.27–1.62 (m, 4 H), 0.96
(t, 3 H, J = 7.3 Hz).
13C NMR (100 MHz, CDCl3): = 151.2, 141.0, 139.3, 137.1, 129.0,
125.8, 115.3, 109.9, 76.8, 74.2, 33.1, 31.5, 26.8, 22.8, 21.1, 14.1.
cis-7-Butyl-5-nonyl-4,5-dihydro-7H-furano[2,3-c]pyran (2e)
Flash chromatography of the crude product gave pure 2e (63%) and
a mixture of 2e and the trans-isomer of 2e (24%). The trans-isomer
of 2e uncontaminated with 2e could not be obtained.
IR (film): 2954, 2927, 1503, 1466, 1378, 1082, 722 cm–1.
1H NMR (400 MHz, CDCl3): = 7.25 (m, 1 H), 6.21 (d, 1 H, J = 1.4
Hz), 4.56 (d, 1 H, J = 2.9 Hz), 3.55 (m, 1 H), 2.39 (m, 2 H), 1.70–
1.20 (m, 22 H), 0.91 (t, 3 H, J = 7.3 Hz), 0.87 (t, 3 H, J = 6.9 Hz).
Anal. Calcd for C18H22O2 (270.4): C, 79.96; H, 8.20. Found: C,
80.17; H, 8.26.
13C NMR (100 MHz, CDCl3): = 151.6, 140.9, 115.2, 110.0, 75.6,
73.9, 35.7, 33.1, 31.9, 29.6 (3 C), 29.5, 29.4, 27.1, 25.9, 22.7, 22.6,
14.2, 14.1.
cis-5,7-Bis(methylethyl)-4,5-dihydro-7H-furano[2,3-c]pyran
(2a) Using Scandium Triflate as Catalyst (Table)
Sc(OTf)3 (0.115 g, 0.0234 mmol) was added to a stirred solution of
the alcohol 1a (0.310 g, 2.01 mmol) in nitromethane (10 mL) and
CH2Cl2 (10 mL) containing MgSO4 (1 g) at 0 °C. After the addition
was complete, isobutyraldehyde (0.19 mL, 2.1 mmol) was added
dropwise over 10 min at 0 °C. The reaction mixture was stirred for
1 h at 0 °C, quenched with H2O (40 mL) and transferred to a sepa-
ratory funnel with EtOAc (40 mL). The organic phase was separat-
ed and washed with H2O (4 20 mL). The combined organic
phases were dried (Na2SO4) and evaporated on the rotary evapora-
Anal. Calcd for C20H34O2 (306.5): C, 78.37; H, 11.18. Found: C,
78.24; H, 11.37.
trans-7-Butyl-5-nonyl-4,5-dihydro-7H-furano[2,3-c]pyran
(trans-Isomer of 2e)
1H NMR (400 MHz, CDCl3): = 7.25 (d, 1 H, J = 1.5 Hz), 6.21 (d,
1 H, J = 1.4 Hz), 4.56 (dd, 1 H, J = 5.5, 7.7 Hz), 3.76 (m, 1 H), 2.45
Synthesis 2002, No. 11, 1541–1545 ISSN 0039-7881 © Thieme Stuttgart · New York