11092
S. Kitagaki et al. / Tetrahedron 64 (2008) 11086–11095
13C NMR
d
167.0, 140.3, 136.0, 128.4, 128.1, 127.9, 125.1, 66.3, 62.5,
104.7, 71.6, 71.1, 66.0, 37.8, 29.5; MS m/z 369 (Mþ, 7.3); HRMS calcd
for C20H19O6N 369.1212, found 369.1207.
32.1, 31.4, 24.5; MS m/z 234 (Mþ, 2.0); HRMS calcd for C14H18O3
234.1256, found 234.1259.
4.6.3. Benzyl 2-[2-hydroxy-2-(4-chlorophenyl)ethyl]-4,
4.4.4. Benzyl 7-hydroxy-2-methyleneheptanoate (10d)
5-dihydrofuran-3-carboxylate (14
A pale yellow oil: IR 3599, 3408, 1690, 1637 cmꢂ1
7.37–7.25 (m, 9H), 5.18 (s, 2H), 4.95 (dd, 1H, J¼9.2, 3.1 Hz), 4.43 (t,
gc)
A colorless oil: IR 3620, 3446, 1712, 1629 cmꢂ1; 1H NMR
d
7.35–
;
1H NMR
7.29 (m, 5H), 6.17 (d, 1H, J¼1.5 Hz), 5.53 (d, 1H, J¼1.5 Hz), 5.17 (s,
d
2H), 3.59 (t, 2H, J¼6.6 Hz), 2.31 (t, 2H, J¼7.3 Hz), 1.61–1.32 (m, 6H);
2H, J¼9.8 Hz), 3.06 (dd, 1H, J¼14.1, 9.2 Hz), 2.98 (dd, 1H, J¼14.1,
13C NMR
d
167.0, 140.4, 136.0, 128.4, 128.0, 127.9, 125.0, 66.3, 62.6,
3.1 Hz), 2.94 (t, 2H, J¼9.8 Hz); 13C NMR
d 168.9, 166.5, 142.2, 136.2,
32.4, 31.7, 28.1, 25.2; MS m/z 248 (Mþ, 2.4); HRMS calcd for
133.1, 128.6, 128.5, 127.6, 127.0, 126.9, 104.2, 71.8, 70.9, 65.9, 37.9,
29.5; MS m/z 358 (Mþ, 2.4); HRMS calcd for C20H19O4Cl 358.0972,
found 358.0962.
C15H20O3 248.1413, found 248.1410.
4.5. Ring-closing reaction of benzyl
methylenealkanoates
u-hydroxy-2-
4.6.4. Benzyl 2-(2-hydroxy-4-phenylbut-3-enyl)-4,5-dihydrofuran-
3-carboxylate (14ge)
A pale yellow oil: IR 3605, 3433, 1726, 1688, 1637 cmꢂ1; 1H NMR
According to the procedure described for ring-closing reaction
of 1-(benzyloxycarbonyl)-1-( -hydroxyalkyl)allenes, benzyl -hy-
d
7.39–7.22 (m, 10H), 6.61 (d, 1H, J¼15.9 Hz), 6.21 (dd, 1H, J¼15.9,
u
u
6.1 Hz), 5.18 (s, 2H), 4.59–4.58 (m, 1H), 4.45 (t, 2H, J¼9.8 Hz), 3.02
(dd, 1H, J¼13.4, 7.9 Hz), 2.96 (dd, 1H, J¼13.4, 4.8 Hz), 2.94 (t, 2H,
droxy-2-methylenealkanoates were exposed to the standard ring-
closing conditions (0.025 M solution was used).
J¼9.8 Hz); 13C NMR
d 169.2, 166.5, 140.9, 136.7, 131.3, 130.1, 128.6,
128.5, 127.7, 127.0, 126.5, 104.1, 70.9, 70.9, 65.4, 36.0, 29.6; MS m/z
4.5.1. 2-(Benzyloxymethyl)-4-butanolide (11a)22
350 (Mþ, 24.1); HRMS calcd for C22H22O4 350.1518, found 350.1512.
A colorless oil: 1H NMR
d 7.25–7.13 (m, 5H), 4.56 (s, 2H), 4.23 (t,
2H, J¼7.3 Hz), 3.56–3.52 (m, 2H), 2.74–2.71 (m, 1H), 2.36 (t, 2H,
4.6.5. Benzyl 2-(2-hydroxyhexyl)-4,5-dihydrofuran-3-
J¼7.3 Hz); 13C NMR
d 177.7, 137.3, 129.2, 128.5, 127.7, 74.6, 71.7, 69.1,
carboxylate (14
gf)
45.1, 24.3.
A pale yellow oil: IR 3600, 3439, 1686, 1637 cmꢂ1
;
1H NMR
d
7.37–7.29 (m, 5H), 5.17 (s, 2H), 4.45 (t, 2H, J¼9.7 Hz), 3.88–3.83 (m,
4.5.2. 2-Methylene-5-pentanolide (12b0)23
A colorless oil: 1H NMR
6.42 (d, 1H, J¼1.6 Hz), 5.56 (d, 1H,
J¼1.6 Hz), 4.37 (t, 2H, J¼5.3 Hz), 2.68 (tt, 2H, J¼6.3, 1.6 Hz), 1.99–
1.90 (m, 2H); 13C NMR
167.2, 131.9, 127.1, 63.6, 25.4, 22.5.
1H), 2.94 (t, 2H, J¼9.7 Hz), 2.84 (dd, 1H, J¼14.1, 3.9 Hz), 2.79 (dd, 1H,
d
J¼14.1, 7.8 Hz), 1.47–1.25 (m, 6H), 0.94–0.88 (m, 3H); 13C NMR
d
170.2, 166.4, 136.4, 128.5, 128.0, 127.0, 103.5, 70.8, 70.3, 65.4, 37.2,
d
35.6, 29.5, 27.6, 22.6, 14.0; MS m/z 304 (Mþ, 3.7); HRMS calcd for
C18H24O4 304.1675, found 304.1677.
4.5.3. 2-Methylene-6-hexanolide (12c0)23
A colorless oil: 1H NMR
d 5.78 (s, 1H), 5.39 (s, 1H), 4.15 (t, 2H,
4.6.6. Benzyl 2-(2-hydroxy-4-methylpentyl)-4,5-dihydrofuran-3-
J¼4.3 Hz), 2.36 (t, 2H, J¼7.4 Hz), 1.92–1.78 (m, 4H); 13C NMR
d 170.7,
carboxylate (14
gg)
142.1, 122.0, 66.7, 29.4, 26.9, 26.7.
A colorless oil: IR 3593, 3445, 1682, 1636 cmꢂ1; 1H NMR
d
7.35–
7.25 (m, 5H), 5.15 (s, 2H), 4.43 (t, 2H, J¼9.7 Hz), 3.95–3.90 (m, 1H),
2.92 (t, 2H, J¼9.7 Hz), 2.81 (dd, 1H, J¼14.1, 3.6 Hz), 2.75 (dd, 1H,
J¼14.1, 7.8 Hz), 1.79–1.72 (m, 1H), 1.24–1.18 (m, 2H), 0.89 (d, 3H,
4.6. General procedure for the ring-closing reaction in the
presence of aldehyde
J¼6.6 Hz), 0.87 (d, 3H, J¼6.6 Hz); 13C NMR
d 170.1, 166.4, 136.4,
To a solution of allene (0.1 mmol) and aldehyde (0.15 mmol) in
solvent (1 mL) was added base (0.1 or 0.15 mmol) at room tem-
perature. The reaction mixture was stirred at that temperature until
the complete disappearance of the starting material as indicated by
TLC. The reaction was quenched by addition of 1% aqueous HCl, and
the mixture was extracted with AcOEt. The extract was washed
with water and brine, dried, and concentrated to dryness. The
residue was chromatographed on silica gel.
128.5, 128.0, 127.0, 103.6, 70.8, 68.4, 65.4, 46.6, 36.0, 29.5, 24.5, 23.2,
22.1; MS m/z 304 (Mþ, 13.3); HRMS calcd for C18H24O4 304.1675,
found 304.1668.
4.6.7. Benzyl 2-(2-hydroxy-3,3-dimethylbutyl)-4,5-dihydrofuran-3-
carboxylate (14
gh)
A colorless oil: IR 3566, 3431, 1680, 1636 cmꢂ1; 1H NMR
d
7.36–
7.33 (m, 5H), 5.17 (s, 2H), 4.46 (t, 2H, J¼9.7 Hz), 3.48 (dd, 1H, J¼10.0,
2.9 Hz), 2.95 (t, 2H, J¼9.7 Hz), 2.81 (dd,1H, J¼13.9,10.0 Hz), 2.72 (dd,
4.6.1. Benzyl 2-(2-hydroxy-2-phenylethyl)-4,5-dihydrofuran-3-
1H, J¼13.9, 2.9 Hz), 0.90 (s, 9H); 13C NMR
d 171.4, 166.7, 136.3, 128.5,
128.1, 128.1, 103.4, 78.0, 70.8, 65.7, 35.2, 30.9, 29.6, 25.4; MS m/z 304
carboxylate (14
g
a)
A colorless oil: IR 3597, 3423, 1686, 1637 cmꢂ1; 1H NMR
d
7.37–
(Mþ, 3.1); HRMS calcd for C18H24O4 304.1675, found 304.1668.
7.28 (m, 10H), 5.18 (s, 2H), 4.98 (dd, 1H, J¼9.3, 3.4 Hz), 4.44 (t, 2H,
J¼9.8 Hz), 3.23 (br s, 1H), 3.13 (dd, 1H, J¼14.1, 9.3 Hz), 2.99 (dd, 1H,
4.6.8. 1-Phenyl-2-(3-phenylsulfonyl-4,5-dihydrofuran-2yl)-
J¼14.1, 3.4 Hz), 2.94 (t, 2H, J¼9.8 Hz); 13C NMR
d
169.2, 166.4, 143.7,
ethanol (16ga)
136.3, 128.6, 128.4, 128.1, 128.1, 127.5, 125.5, 104.0, 72.5, 70.9, 65.8,
38.1, 29.6; MS m/z 324 (Mþ,1.5); HRMS calcd for C20H20O4 324.1362,
found 324.1363.
A pale yellow oil: IR 3597, 3504, 1632 cmꢂ1; 1H NMR
d 7.82–7.79
(m, 2H), 7.61–7.27 (m, 8H), 5.06 (dd, 1H, J¼9.0, 3.9 Hz), 4.43 (t, 2H,
J¼9.6 Hz), 3.25 (dd, 1H, J¼14.2, 9.0 Hz), 3.06 (dd, 1H, J¼14.2, 3.9 Hz),
2.86 (t, 2H, J¼9.6 Hz); 13C NMR
d 166.2, 143.3, 141.3, 132.9, 129.1,
128.5, 127.8, 126.9, 125.6, 110.8, 71.9, 70.3, 37.0, 30.2; MS m/z 330
4.6.2. Benzyl 2-[2-hydroxy-2-(3-nitrophenyl)ethyl]-4,
5-dihydrofuran-3-carboxylate (14
g
b)
(Mþ, 9.2); HRMS calcd for C18H18O4S 330.0926, found 330.0936.
A colorless oil: IR 3549, 3387, 1691, 1637 cmꢂ1; 1H NMR
d
8.26 (s,
1H), 8.12–8.11 (m, 1H), 7.65 (d, 1H, J¼7.9 Hz), 7.47 (t, 1H J¼7.9 Hz),
4.6.9. 1-(4-Methoxyphenyl)-2-(3-phenylsulfonyl-4,5-dihydrofuran-
7.36–7.33 (m, 5H), 5.19 (s, 2H), 5.09 (t, 1H, J¼6.1 Hz), 4.45–4.40 (m,
2yl)ethanol (16
A pale yellow oil: IR 3599, 3508, 1632 cmꢂ1; 1H NMR
(m, 2H), 7.58–7.44 (m, 3H), 7.32 (d, 2H, J¼8.7 Hz), 6.87 (d, 2H,
gd)
2H), 3.09 (d, 2H, J¼6.1 Hz), 2.95 (t, 2H, J¼9.2 Hz); 13C NMR
d
168.3,
d 7.77–7.74
166.7,148.4,145.8,136.1,131.7,129.3,128.6,128.3,128.1,122.5,120.7,