(m, 2H), 4.16–4.21 (m, 1H), 5.73 (s, 1H), 6.31 (d, J = 4.4 Hz,
1H), 7.10–7.14 (m, 1H), 7.16 (dd, J = 7.6 Hz, 1.6 Hz, 1H),
7.26–7.30 (m, 1H), 7.57 (dd, J = 7.6 Hz, 1.6 Hz, 1H); 13C NMR
(CDCl3, 100 MHz, TMS) δ 14.2, 28.0, 28.2, 35.2, 59.8, 82.6,
101.3, 114.1, 124.0, 127.9, 128.4, 128.8, 133.1, 140.2, 143.1,
160.1, 164.1, 166.7; IR (CH2Cl2) ν 2980, 2360, 2342, 1734,
1717, 1654, 1472, 1372, 1275, 1260, 1165, 1113, 848, 750,
669 cm−1; MS (ESI) m/z 423.0 (M + H+); HRMS (ESI) Calcd
for C20H24BrO5 requires (M + H+): 423.0802, Found: 423.0810;
[α]2D0 = −52.9 (c 2.00, CH2Cl2) (80% ee); Chiralcel IC, hexane/
iPrOH = 98/2, 0.6 mL min−1, 254 nm, tmajor = 29.29 min, tminor
= 25.58 min.
351.1261, Found: 351.1275; [α]2D0 = −178.8 (c 0.50, CH2Cl2)
(91% ee); Chiralcel IC, hexane/iPrOH = 98/2, 0.6 mL min−1
,
254 nm, tmajor = 26.81 min, tminor = 30.47 min.
(E)-Ethyl
4-cyclopropyl-2-(2-ethoxy-2-oxoethylidene)-3,4-
dihydro-2H-pyran-6-carboxylate 3oa. A slightly yellow liquid
(26.0 mg, 83%); This is a known compound;8f 1H NMR
(CDCl3, 400 MHz, TMS) δ 0.23–0.26 (m, 2H), 0.52–0.56 (m,
2H), 0.70–0.76 (m, 1H), 1.28 (t, J = 7.2 Hz, 3H), 1.35 (t, J = 7.2
Hz, 3H), 1.72–1.79 (m, 1H), 2.92 (dd, J = 15.2 Hz, 8.4 Hz, 1H),
3.48 (dd, J = 15.2 Hz, 5.6 Hz, 1H), 4.16 (q, J = 7.2 Hz, 2H),
4.27–4.32 (m, 2H), 5.70 (s, 1H), 6.32 (d, J = 4.0 Hz, 1H); [α]D20
= −69.1 (c 1.00, CH2Cl2) (86% ee); Chiralcel OJ-H, hexane/
iPrOH = 98/2, 0.6 mL min−1, 254 nm, tmajor = 17.47 min, tminor
= 22.76 min.
(E)-tert-Butyl 2-(2-ethoxy-2-oxoethylidene)-4-(naphthalen-2-
yl)-3,4-dihydro-2H-pyran-6-carboxylate 3la. A slightly yellow
1
liquid (46.2 mg, 90%); H NMR (CDCl3, 400 MHz, TMS) δ
1.21 (t, J = 7.2 Hz, 3H), 1.55 (s, 9H), 3.27 (dd, J = 15.6 Hz, 8.0
Hz, 1H), 3.69 (dd, J = 15.6 Hz, 6.0 Hz, 1H), 3.83–3.87 (m, 1H),
4.04–4.12 (m, 2H), 5.75 (s, 1H), 6.42 (d, J = 4.0 Hz, 1H), 7.34
(dd, J = 8.4 Hz, 1.6 Hz, 1H), 7.43–7.50 (m, 2H), 7.64 (s, 1H),
7.78–7.83 (m, 3H); 13C NMR (CDCl3, 100 MHz, TMS) δ 14.2,
28.0, 29.5, 35.9, 59.8, 82.5, 100.8, 115.3, 125.5, 125.80, 125.84,
126.2, 127.6, 127.7, 128.6, 132.5, 133.4, 138.8, 142.5, 160.2,
164.8, 167.0; IR (CH2Cl2) ν 2979, 2931, 2359, 2341, 1733,
1717, 1654, 1508, 1457, 1394, 1373, 1260, 1163, 1113, 847,
749 cm−1; MS (ESI) m/z 395.1 (M + H+); HRMS (ESI) Calcd
for C24H27O5 requires (M + H+): 395.1853, Found: 395.1865;
[α]2D0 = −301.6 (c 1.50, CH2Cl2) (91% ee); Chiralcel IC,
hexane/iPrOH = 98/2, 0.6 mL min−1, 254 nm, tmajor = 34.00 min,
Acknowledgements
We thank the Shanghai Municipal Committee of Science and
Technology (11JC1402600), National Basic Research Program
of China (973)-2009CB825300, the Fundamental Research
Funds for the Central Universities and the National Natural
Science Foundation of China for financial support (21072206,
20472096, 20872162, 20672127, 21121062 and 20732008).
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tminor = 30.70 min.
(E)-tert-Butyl 2-(2-ethoxy-2-oxoethylidene)-4-(furan-2-yl)-3,4-
dihydro-2H-pyran-6-carboxylate 3ma. A slightly yellow liquid
1
(24.0 mg, 72%); H NMR (CDCl3, 400 MHz, TMS) δ 1.27 (t, J
= 7.2 Hz, 3H), 1.52 (s, 9H), 3.35 (dd, J = 15.6 Hz, 7.6 Hz, 1H),
3.52 (dd, J = 15.6 Hz, 6.0 Hz, 1H), 3.76–3.80 (m, 1H), 4.15 (dq,
J = 7.2 Hz, 1.6 Hz, 2H), 5.73 (s, 1H), 6.12 (d, J = 3.2 Hz, 1H),
6.30 (dd, J = 3.2 Hz, 1.6 Hz, 1H), 6.34 (d, J = 4.4 Hz, 1H), 7.35
(d, J = 1.6 Hz, 1H); 13C NMR (CDCl3, 100 MHz, TMS) δ 14.3,
26.4, 28.0, 29.7, 59.9, 82.6, 101.1, 105.6, 110.3, 112.5, 142.0,
142.5, 153.7, 160.1, 164.4, 167.0; IR (CH2Cl2) ν 2360, 2342,
1733, 1716, 1275, 1260, 1116, 846, 750, 669, cm−1; MS (ESI)
m/z 357.1 (M + Na+); HRMS (ESI) Calcd for C18H22O6Na
requires (M + Na+): 357.1309, Found: 357.1322; [α]2D0 = −42.0
(c 0.30, CH2Cl2) (90% ee); Chiralcel IC, hexane/iPrOH = 98/2,
0.6 mL min−1, 254 nm, tmajor = 23.11 min, tminor = 26.68 min.
(E)-tert-Butyl 2-(2-ethoxy-2-oxoethylidene)-4-(thiophen-2-yl)-
3,4-dihydro-2H-pyran-6-carboxylate 3na. A slightly yellow
1
liquid (26.3 mg, 75%); H NMR (CDCl3, 400 MHz, TMS) δ
1.25 (t, J = 7.2 Hz, 3H), 1.53 (s, 9H), 3.40 (dd, J = 15.6 Hz, 7.2
Hz, 1H), 3.54 (dd, J = 15.6 Hz, 6.0 Hz, 1H), 3.96–4.00 (m, 1H),
4.13 (dq, J = 7.2 Hz, 2.4 Hz, 2H), 5.75 (s, 1H), 6.37 (d, J = 4.4
Hz, 1H), 6.90 (d, J = 3.2 Hz, 1H), 6.95 (dd, J = 5.2 Hz, 3.2 Hz,
1H), 7.20 (d, J = 5.2 Hz, 1H); 13C NMR (CDCl3, 100 MHz,
TMS) δ 14.2, 28.0, 29.7, 31.2, 59.9, 82.6, 101.4, 114.8, 124.3,
124.4, 126.9, 142.1, 144.4, 160.1, 164.2, 166.9; IR (CH2Cl2) ν
2983, 2360, 2342, 1733, 1715, 1659, 1507, 1372, 1276, 1260,
1115, 848, 750, 668 cm−1; MS (ESI) m/z 351.1 (M + H+);
HRMS (ESI) Calcd for C18H23SO5 requires (M + H+):
4360 | Org. Biomol. Chem., 2012, 10, 4355–4361
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