S. Zhu et al. / Tetrahedron 67 (2011) 5507e5515
5513
2957, 2924, 2655, 1750, 1644, 1516, 1442, 1325, 1214, 1171, 1130,
1069, 1017, 849, 768, 697, 603. HRMS (ESI): calcd for
C19H16F3NO7[M þ Na]þ, 450.0771, found. 450.0781.
NMR (400 MHz, CDCl3):
d
7.39e7.28 (m, 2H), 6.93e6.88 (m, 2H),
6.24 (s, 1H), 3.87 (s, 3H), 3.81 (s, 3H), 3.70 (s, 3H), 1.56 (s, 9H). 13C
NMR (100 MHz, CDCl3):
129.0, 126.9, 114.8, 114.4, 90.9, 86.0, 84.4, 55.3, 53.1, 53.0, 27.6.
trans-1H NMR (400 MHz, CDCl3):
7.39e7.28 (m, 2H), 6.93e6.88
(m, 2H), 6.23 (s, 3H), 3.89 (s, 3H), 3.82 (s, 3H), 3.71 (s, 3H), 1.55 (s,
9H). 13C NMR (100 MHz, CDCl3):
162.4, 161.4, 160.8, 159.5, 147.1,
129.5, 129.1, 126.8, 114.7, 114.2, 91.5, 86.1, 84.6, 55.3, 53.1, 53.0, 27.6.
IR: 2959, 2844, 1748, 1616, 1515, 1441, 1259, 1160, 1028, 984,
837, 778, 734, 609, 540. HRMS (ESI): calcd for C21H23NO8[M þ Na]þ,
440.1316, found 440.1316.
d 162.5, 161.6, 160.8, 159.7, 146.2, 129.7,
4.3.7. 2-Ethyl 3,4-dimethyl 2-cyano-5-(4-nitrophenyl)-2,5-
d
dihydrofuran-2,3,4-tricarboxylate (10e). Yellow oil, cis-1H NMR
(400 MHz, CDCl3):
(s, 1H), 4.46e4.38 (m, 2H), 3.91 (s, 3H), 3.75 (s, 3H), 1.39 (t, J¼7.2 Hz,
3H). 13C NMR (100 MHz, CDCl3):
163.2, 160.7, 159.2, 148.8, 144.7,
141.7, 130.1, 128.3, 124.3, 123.1, 114.1, 90.4, 84.5, 64.6, 53.5, 53.4, 13.9.
trans-1H NMR (400 MHz, CDCl3):
8.26 (d, J¼8.8 Hz, 2H), 7.70 (d,
d
8.29 (d, J¼8.8 Hz, 2H), 7.59 (d, J¼8.8 Hz, 2H), 6.40
d
d
d
J¼8.8 Hz, 2H), 6.42(s,1H), 4.46e4.38(m, 2H), 3.89(s, 3H), 3.73(s, 3H),
1.39 (t, J¼7.2 Hz, 3H).13C NMR (100 MHz, CDCl3):
d
163.4,160.8,159.1,
4.3.13. 2-tert-Butyl 3,4-dimethyl 5-(4-bromophenyl)-2-cyano-2,5-
148.9,145.4,141.4,130.5,129.1,124.1,113.8, 90.0, 84.3, 64.7, 53.5, 53.4,
13.9. IR: 2959, 2853, 1752, 1641, 1528, 1441, 1350, 1262, 1208, 1139,
1098, 1055, 1020, 926, 859, 822, 782, 746, 697, 617, 486. HRMS (ESI):
calcd for C18H16N2O9[M þ Na]þ, 427.0748, found 427.0750.
dihydrofuran-2,3,4-tricarboxylate (10c0). Pale yellow oil, cis-1H NMR
(400 MHz, CDCl3):
3.73 (2, 3H), 1.55 (s, 9H). 13C NMR (100 MHz, CDCl3):
159.6, 145.1, 134.1, 132.3, 130.3, 129.0, 124.2, 114.5, 91.0, 86.5, 84.7,
53.2, 53.1, 27.6. trans-1H NMR (400 MHz, CDCl3):
7.56e7.24 (m,
4H), 6.24 (s, 1H), 3.88 (s, 3H), 3.71 (2, 3H), 1.57 (s, 9H). 13C NMR
(100 MHz, CDCl3): 162.2, 161.2, 159.3, 146.0, 133.9, 132.1, 129.9,
d
7.56e7.24 (m, 4H), 6.23 (s, 1H), 3.89 (s, 3H),
d
162.2, 161.1,
d
4.3.8. 2-Ethyl 3,4-dimethyl 2-cyano-5-(perfluorophenyl)-2,5-
dihydrofuran-2,3,4-tricarboxylate (10f). Yellow oil, 1H NMR
d
(400 MHz, CDCl3)
d
6.61 (s, 1H), 4.36 (q, J¼8 Hz, 2H), 3.92 (s, 3H),
129.8, 124.33, 114.4, 90.4, 86.4, 84.9, 53.2, 53.1, 27.6. IR: 2984, 2955,
1752, 1644, 1591, 1486, 1439, 1399, 1369, 1337, 1278, 1208, 1154,
1095, 1011, 921, 833, 784, 476. HRMS (ESI): calcd for
C20H20BrNO7[M þ Na]þ, 488.0315, found 488.0321.
3.81 (s, 3H), 1.34 (t, J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3) 162.0,
160.1, 159.4, 152.2, 147.0 (m), 144.5 (m), 140.1, 136.5 (m), 133.2,113.4,
84.2, 79.7, 64.5, 53.5, 53.5, 13.7. 19F NMR (360 MHz, CDDCl3)
d
ꢀ140.74 to ꢀ140.82 (m, 2F), ꢀ149.64 to ꢀ149.77 (m, 1F), ꢀ160.51
to ꢀ160.64 (m, 2F). IR: 2959, 2362, 1751, 1653, 1510, 1440, 1264,
1207, 1128, 1100, 1027, 999, 926, 853, 768, 621. HRESI: calcd for
C18H12NO7[M þ Na]þ, 472.0426, found 472.0427.
4.3.14. 2-tert-Butyl 3,4-dimethyl 2-cyano-5-(4-(trifluoromethyl)-
phenyl)-2,5-dihydrofuran-2,3,4-tricarboxylate (10d0). Yellow oil,
cis-1H NMR (400 MHz, CDCl3):
d
7.69e7.50 (m, 4H), 6.34 (s, 1H),
3.89 (s, 3H), 3.71 (s, 3H), 1.58 (s, 9H). 13C NMR (100 MHz, CDCl3):
162.1, 161.1, 159.3, 145.6, 138.8, 132.12, 131.8, 130.3, 128.5, 125.8
(m), 114.3, 90.3, 86.5, 85.0, 53.2, 53.1, 27.6. trans-1H NMR (400 MHz,
CDCl3): 7.69e7.50 (m, 4H), 6.33 (s, 1H), 3.90 (s, 1H), 3.73 (s, 1H),
1.56 (s, 1H). 13C NMR (100 MHz, CDCl3):
162.1, 160.91, 159.5, 144.6,
4.3.9. (E)-2-Ethyl 3,4-dimethyl 2-cyano-5-styryl-2,5-dihydrofuran-
d
2,3,4-tricarboxylate (10g). Brown oil, 1H NMR (400 MHz, CDCl3):
d
7.58e5.92 (m, 8H), 4.43e4.35 (m, 2H), 3.88e3.84 (m, 3H), 3.81e3.74
d
(m, 3H),1.39 (t, J¼7 Hz, 3H).13C NMR (100 MHz, CDCl3):
d
168.1,163.7,
d
163.3, 162.1, 140.8, 135.0, 130.2, 128.9, 128.1, 115.2, 113.6, 102.6, 79.3,
64.6, 58.1, 53.2, 51.9,13.9. IR: 2956, 2852,1750,1709,1641,1600,1443,
1346,1261,1207,1134,1083,1019, 855, 758, 693, 613, 491. HRMS (ESI):
calcd for C20H19NO7[M þ Na]þ, 408.1054, found 408.1063.
139.5,132.1,131.8,130.3,127.8,126.1 (m),114.4, 90.7, 86.6, 84.9, 53.2,
53.2, 27.6. IR: 2986, 2362, 1751, 1673, 1625, 1440, 1372, 1328, 1271,
1166, 1132, 1069, 1024, 990, 837, 775, 734, 672, 608. HRMS (ESI):
calcd for C20H20NO7[M þ Na]þ, 478.1084, found 478.1094.
4.3.10. 2-Ethyl 3,4-dimethyl 2-cyano-5-(furan-2-yl)-2,5-
4.3.15. 2-tert-Butyl 3,4-dimethyl 2-cyano-5-(4-nitrophenyl)-2,5-di-
dihydrofuran-2,3,4-tricarboxylate (10h). Brown oil, cis-1H NMR
hydrofuran-2,3,4-tricarboxylate (10e0). Yellow oil, cis-1H NMR
(400 MHz, CDCl3):
d
7.50e7.46 (m, 1H), 6.55e6.56 (m, 1H),
(400 MHz, CDCl3):
1H), 3.90 (s, 3H), 3.72 (s, 3H), 1.59 (s, 9H). 13C NMR (100 MHz,
CDCl3): 162.0, 160.7, 159.2, 184.8, 144.8, 141.8, 130.82, 129.1, 124.0,
114.1, 89.7, 86.8, 85.1, 53.3, 53.2, 27.6. trans-1H NMR (400 MHz,
CDCl3): 8.29e8.25 (m, 2H), 7.73e7.58 (m, 2H), 6.38 (s, 1H), 3.91 (s,
3H), 3.74 (s, 3H), 1.57 (s, 9H). 13C NMR (100 MHz, CDCl3):
161.9,
160.7, 159.4, 148.4, 143.8, 142.0, 131.3, 128.3, 124.2, 114.2, 90.2, 86.8,
85.0, 53.3, 53.3, 27.6. HRMS (ESI): calcd for C20H20N2O9[M þ Na]þ,
455.1061, found 455.1070.
d 8.29e8.25 (m, 2H), 7.73e7.58 (m, 2H), 6.40 (s,
6.41e6.39 (m, 1H), 6.38 (s, 1H), 4.40e4.31 (m, 2H), 3.88 (s, 3H), 3.79
(s, 3H), 1.33 (t, J¼7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3):
d
163.1,
d
161.0, 159.3, 147.2, 144.4, 143.4, 130.6, 114.1, 111.9, 111.1, 83.7, 83.7,
64.2, 53.3, 53.3, 13.8. trans-1H NMR (400 MHz, CDCl3):
d
7.50e7.46
d
(m, 1H), 6.55e6.56 (m, 1H), 6.41e6.39 (m, 1H), 6.30 (s, 1H),
4.40e4.31 (m, 2H), 3.89 (s, 3H), 3.79 (s, 3H), 1.36 (t, J¼7.2 Hz, 3H).
d
13C NMR (100 MHz, CDCl3):
d 163.5, 160.9, 159.3, 147.2, 144.7, 142.9,
131.1, 113.9, 111.6, 112.0, 84.0, 83.4, 64.3, 53.3, 53.2, 13.9. IR: 2956,
2921, 2851, 1740, 1676, 1444, 1256, 1024, 744. HRMS (ESI): calcd for
C16H15NO8[M þ Na]þ, 372.0690, found 372.0704.
4.3.16. 2-tert-Butyl 3,4-dimethyl 2-cyano-5-(perfluorophenyl)-2,5-
dihydrofuran-2,3,4-tricarboxylate (10f0). Yellow oil, cis-1H NMR
4.3.11. 2-tert-Butyl 3,4-dimethyl 2-cyano-5-phenyl-2,5-
(400 MHz, CDCl3):
9H). 13C NMR (100 MHz, CDCl3):
144.5 (m), 139.0, 136.4 (m), 134.3, 113.7, 86.8, 84.9, 79.4, 53.4, 53.4,
53.4, 27.5. trans-1H NMR (400 MHz, CDCl3):
6.60 (s, 1H), 3.94 (s,
3H), 3.78 (s, 3H), 1.56 (s, 9H). 13C NMR (100 MHz, CDCl3):
161.9,
160.6, 159.6, 143.8 (m), 141.3 (m), 139.2, 138.9 (m), 133.9, 113.3, 87.1,
84.9, 80.3, 53.4, 53.34, 53.4, 27.7. IR: 2958, 1751, 1512, 1443, 1262,
1207, 1154, 1101, 996, 834, 782. HRMS (ESI): calcd for
C20H16F5NO7[M þ Na]þ, 500.0739, found 500.0747.
d
6.58 (s, 1H), 3.94 (s, 3H), 3.79 (s, 3H), 1.51 (s,
dihydrofuran-2,3,4-tricarboxylate (10a0). Yellow oil, cis-1H NMR
d
161.9, 160.2, 159.8, 147.0 (m),
(400 MHz, CDCl3):
(s, 3H), 1.57 (s, 9H). 13C NMR (100 MHz, CDCl3):
146.9, 134.7, 130.0, 129.4, 128.8, 128.1, 114.6, 91.2, 86.1, 84.9, 53.1,
54.0, 27.6. trans-1H NMR (400 MHz, CDCl3):
7.47e7.38 (m, 5H), 6.27
(s, 1H), 3.89 (s, 3H), 3.71 (s, 3H), 1.55 (s, 9H). 13C NMR (100 MHz,
CDCl3): 162.4, 161.3, 159.7, 146.0, 135.0, 129.9, 129.7, 129.1, 127.4,
d
7.47e7.38 (m, 5H), 6.29 (s,1H), 3.87 (s, 3H), 3.69
d
162.3, 161.5, 159.4,
d
d
d
d
114.7, 91.8, 86.3, 84.8, 53.1, 53.0, 27.6. IR: 2960, 1750, 1673, 1440,
1266, 1205, 1157, 1026, 986, 923, 834, 748, 699, 620. HRMS (ESI):
calcd for C20H21NO7[M þ Na]þ, 410.1210, found 410.1222.
4.3.17. (E)-2-tert-Butyl 3,4-dimethyl 2-cyano-5-styryl-2,5-
dihydrofuran-2,3,4-tricarboxylate (10g0). Yellow oil, 1H NMR
4.3.12. 2-tert-Butyl 3,4-dimethyl 2-cyano-5-(4-methoxyphenyl)-2,5-
(400 MHz, CDCl3):
d
7.57e7.38 (m, 8H), 3.80e3.75 (m, 6H),
168.2, 163.8, 163.3,
dihydrofuran-2,3,4-tricarboxylate (10b0). Pale yellow oil, cis-1H
1.56e1.54 (s, 9H). 13C NMR (100 MHz, CDCl3):
d