(m, 4H, signal obscured with moisture peak), 2.10–2.37 (m, 1H),
3.47–3.58 (m, 1H), 3.64–3.75 (m, 2H);13C NMR (100 MHz
CDCl3): δ 11.64 (CH3), 11.82 (CH3), 13.46 (CH3), 14.62 (CH3),
24.82 (CH2), 25.83 (CH2), 29.56 (CH2, C-4), 29.81 (CH2, C-4),
30.36 (CH2, C-3), 31.43 (CH2, C-3), 40.44 (CH), 40.69 (CH),
62.96 (CH2, C-5), 63.00 (CH2, C-5), 75.08 (CH, C-2), 75.72
(CH, C-2); GC MS (EI) m\z (relative intensity): 127.2 (19.8),
95.2 (29.3), 84.2 (11.1), 82.2 (10.9), 71.2 (57.2), 69.3 (21.2),
67.3 (21.8), 61.2 (15.0), 43.1 (99.9), 41.2 (85.0).
3.80–3.89 (m, CH of 6b/f and OCH3 of both 6b/f and 7b/f),
4.62–4.69 (m, CH of 6b/f), 6.85–7.35 (m, aromatic protons);
13C NMR (100 MHz, CDCl3): 23.18 (CH3, 6b/f), 23.51 (CH3,
6b/f), 27.16 (CH2, C-4, 7b/f), 30.40 (CH3, 7b/f), 34.90 (CH2,
C-3, 6b/f), 34.92 (CH2, C-3, 6b/f), 35.96 (CH2, C-4, 6b/f),
36.03 (CH2, C-4, 6b/f), 41.08 (CH2, C-3, 7b/f), 55.21 (OCH3),
55.24 (OCH3), 55.35 (OCH3), 62.69 (CH2, C-5, 7b/f), 67.54
(CH, C-5, 6b/f), 68.06 (CH, C-5, 6b/f), 73.59 (CH, C-2, 6b/f),
73.93 (C, C-2, 7b/f), 74.11 (CH, C-2, 6b/f), 111.40 (C-Ar),
113.38 (C-Ar), 113.71 (C-Ar), 120.90 (C-Ar), 126.05 (C-Ar),
126.80 (C-Ar), 127.06 (C-Ar), 127.09 (C-Ar), 128.10 (C-Ar),
136.96 (C-Ar), 137.17 (C-Ar), 140.30 (C-Ar), 156.60 (C-Ar),
158.00 (C-Ar), 158.76 (C-Ar); GC MS for 6b/f (EI) m\z (relative
intensity): 191.1 (M-1, 29.4), 177.1 (12.7), 175.2 (45.0), 150.2
(10.0), 147.2 (21.6), 135.3 (99.9), 134.4 (32.2), 121.3 (16.0),
109.3 (38.5), 107.3 (7.1), 91.1 (21.3), 77.1 (33.9), 78.1 (13.4),
43.0 (8.0); for 7b/f: 193.1 (M+1, 13.1), 177.1 (99.9), 175.3
(11.6), 151.2 (30.9), 148.3 (18.4), 135.3 (81.9), 115.3 (6.2), 92.0
(6.6), 77.1 (18.3), 63.1 (6.3), 43.0 (18.1).
General procedure for cross-coupling of organometallic species
with 2-methyl THF
In an oven dried flask, dried halo group-containing compounds
(10 mmol) were added in dry 2-methyl THF containing mag-
nesium or lithium (15 mmol, catalytic amount of iodine in case
of magnesium) at 0 °C. The whole reaction mixture was stirred
vigorously until organometallic species generation occurred. The
reaction mixture was stirred at rt for an additional one hour. The
resulting mixture was then added dropwise to a solution contain-
ing 1 mol% ferric oxide in dry 2-methyl THF at 0 °C and then
allowed to stir at rt, the progress of the reaction was monitored
by TLC. After completion, saturated NH4Cl solution was added
and the reaction mixture was extracted with ethyl acetate (3 ×
25 ml). The organic layer was dried over sodium sulphate. The
volatiles were removed in vaccuo. The resultant compounds
were purified on flash silica gel column chromatography using
hexane/EtOAc as the eluent. Pure compounds were analyzed by
NMR (1H/13C/DEPT) and mass spectroscopy.
2-Methyl-5-(naphthalen-1-yl)-tetrahydrofuran (6c/g) and
2-methyl-2-(naphthalen-1-yl)-tetrahydrofuran (7c/g) (Table 3,
entries c and g). White solid; m.p. = 110 °C TLC (EtOAc:
hexane 3 : 7): Rf 0.42; 1H NMR (400 MHz, CDCl3): δ 1.20–1.21
(d, CH3 of 6c/g), 1.43–1.71 (m, CH2 of 2-MTHF), 1.84 (s, 3H
of 7c/g), 2.14–2.46 (m, CH2 of 2-MTHF), 3.56–3.59 (m, 2H of
7c/g), 3.87–3.95 (m, CH of 6c/g), 5.47–5.54 (m, CH of 6c/g),
7.39–8.66 (m, aromatic protons); 13C NMR (100 MHz, CDCl3):
23.15 (CH3, 6c/g), 23.52 (CH3, 6c/g), 27.52 (CH2, C-4, 7c/g),
29.80 (CH3, 7c/g), 34.20 (CH2, C-3, 6c/g), 35.02 (CH2, C-3,
6c/g), 35.45 (CH2, C-4, 6c/g), 36.22 (CH2, C-4, 6c/g), 39.58
(CH2, C-3, 7c/g), 62.58 (CH2, C-5, 7c/g), 67.67 (CH, C-5, 6c/g),
68.13 (CH, C-5, 6c/g), 70.47 (CH, C-2, 6c/g), 71.06 (CH, C-2,
6c/g), 75.81 (C, C-2, 7c/g), 122.88 (C-Ar), 123.07 (C-Ar),
123.22 (C-Ar), 123.90 (C-Ar), 124.97 (C-Ar), 125.07 (C-Ar),
125.26 (C-Ar), 125.46 (C-Ar), 125.52 (C-Ar), 125.94 (C-Ar),
126.78 (C-Ar), 127.64 (C-Ar), 128.36 (C-Ar), 128.92 (C-Ar),
129.24 (C-Ar), 130.35 (C-Ar), 130.84 (C-Ar), 133.80 (C-Ar),
134.89 (C-Ar), 140.46 (C-Ar), 140.70 (C-Ar), 142.83 (C-Ar);
GC MS for 6c/g (EI) m\z (relative intensity): 212 (M+, 26.5),
197.1 (17.9), 195.1 (9.7), 167.2 (18.5), 157.2 (66.5), 155.3
(51.6), 153.4 (32.0), 152.4 (24.9), 141.3 (16.4), 129.3 (99.9),
127.4 (39.0), 115.4 (13.0), 77.1 (7.9), 43.0 (14.9); for 7c/g: 212
(M+, 16.4), 197.1 (99.9), 178.2 (10.7), 167.3 (21.7), 166.3
(37.9), 165.3 (56.9), 155.3 (86.0), 128.3 (25.1), 127.3 (54.9),
102.3 (5.4), 77.1 (8.6), 43.0 (14.9).
2-Methyl-5-phenyl-tetrahydrofuran (6a/e) and 2-methyl-2-
phenyl-tetrahydrofuran (7a/e) (Table 3, entries a and e). Brown-
ish liquid TLC (EtOAc: hexane 3 : 7): Rf 0.37; 1H NMR
(400 MHz, CDCl3): δ 1.18–1.20 (d, CH3 of 6a/e), 1.47–1.53
(m, CH2 of 2-MTHF), 1.57 (s, 3H of 7a/e), 1.80–2.05 (m, CH2
of 2-MTHF), 3.55–3.65 (m, 2H of 7a/e), 3.82–3.89 (m, CH of
6a/e), 4.68–4.75 (m, CH of 6a/e), 7.21–7.44 (m, aromatic
protons); 13C NMR (100 MHz, CDCl3): 23.04 (CH3, 6a/e),
23.39 (CH3, 6a/e), 26.97 (CH2, C-4, 7a/e), 30.28 (CH3, 7a/e),
34.69 (CH2, C-3, 6a/e), 34.88 (CH2, C-3, 6a/e), 35.78 (CH2,
C-4, 6a/e), 36.01 (CH2, C-4, 6a/e), 40.89 (CH2, C-3, 7a/e),
62.49 (CH2, C-5, 7a/e), 67.47 (CH, C-5, 6a/e), 67.98 (CH, C-5,
6a/e), 73.83 (CH, C-2, 6a/e), 74.18 (C, C-2, 7a/e), 74.39 (CH,
C-2, 6a/e), 124.85 (C-Ar), 125.85 (C-Ar), 125.87 (C-Ar),
126.28 (C-Ar), 127.16 (C-Ar), 127.21 (C-Ar), 128.01 (C-Ar),
128.24 (C-Ar), 128.26 (C-Ar), 144.67 (C-Ar), 144.87 (C-Ar),
148.00 (C-Ar); GC MS for 6a/e (EI) m\z (relative intensity):
162.2 (M+, 21.7), 145.3 (53.3), 117.3 (27.7), 107.3 (63.2), 91.1
(20.8), 85.2 (7.5), 79.2 (99.9), 77.2 (64.4), 43.2 (15.6); for 7a/e:
163.2 (M+1, 28.2), 147.2 (50.6), 146.3 (11.9), 145.3 (99.9),
121.3 (67.5), 117.4 (11.7), 105.3 (53.0), 91.2 (14.1), 77.2 (26.1),
51.1 (6.8), 43.1 (52.0).
2-(4-Chlorophenyl)-5-methyl-tetrahydrofuran (6d/h) and 2-(4-
chlorophenyl)-2-methyl-tetrahydrofuran (7d/h) (Table 3, entries
d and h). Brownish liquid TLC (EtOAc : hexane 3 : 7): Rf 0.34;
1H NMR (400 MHz, CDCl3): δ 1.16–1.17 (d, CH3 of 6d/h),
1.45–1.58 (m, CH2 of 2-MTHF), 1.52 (s, 3H of 7d/h),
1.80–2.00 (m, CH2 of 2-MTHF), 3.56–3.60 (m, 2H of 7d/h),
3.81–3.87 (m, CH of 6d/h), 4.68–4.71 (m, CH of 6d/h),
7.25–7.35 (m, aromatic protons); 13C NMR (100 MHz, CDCl3):
23.25 (CH3, 6d/h), 23.59 (CH3, 6d/h), 26.93 (CH2, C-4, 7d/h),
30.49 (CH3, 7d/h), 34.55 (CH2, C-3, 6d/h), 34.96 (CH2, C-3,
6d/h), 35.77 (CH2, C-4, 6d/h), 36.21 (CH2, C-4, 6d/h), 41.05
(CH2, C-3, 7d/h), 62.64 (CH2, C-5, 7d/h), 67.63 (CH, C-5,
2-(4-Methoxyphenyl)-5-methyl-tetrahydrofuran (6b/f) and
2-(4-methoxyphenyl)-2-methyl-tetrahydrofuran (7b/f) (Table 3,
entries b and f). Brownish liquid TLC (EtOAc : hexane 3 : 7): Rf
0.28; 1H NMR (400 MHz, CDCl3): δ 1.17–1.19 (d, CH3 of
6b/f), 1.46–1.58 (m, CH2 of 2-MTHF and CH3 of 7b/f),
1.83–1.98 (m, CH2 of 2-MTHF), 3.57–3.61 (m, 2H of 7b/f),
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Org. Biomol. Chem., 2012, 10, 1587–1597 | 1595