Photochemical C–C Bond Formation
methyltetrahydro-[3,3Ј]bifuranyl-2,2Ј-dione (Dimer 5f-3), and
3S,4S,3ЈS,4ЈR- and 3R,4R,3ЈR,4ЈS-4,5,5,4Ј,5Ј,5Ј-Hexamethyltetra-
hydro-[3,3Ј]bifuranyl-2,2Ј-dione (Dimer 5f-4)[14a]
Data for 5f-3: White powder, m.p. 160.5–161 °C. 1H NMR
(400 MHz, CDCl3): δ = 1.07 (d, J = 7.3 Hz, 3 H), 1.18 (d, J =
6.9 Hz, 3 H), 1.28 (s, 3 H), 1.38 (s, 3 H), 1.43 (s, 3 H), 1.47 (s, 3
H), 2.47 (dd, J = 11.5, 7.3 Hz, 1 H), 2.60 (dd, J = 7.5, 6.9 Hz, 1
H), 2.78 (dd, J = 11.5, 7.3 Hz, 1 H), 3.13 (dd, J = 7.5, 7.3 Hz, 1
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 11.8, 14.1, 22.2, 23.8,
27.5, 27.6, 41.5, 43.2, 43.8, 43.9, 85.1, 85.4, 175.0, 175.7 ppm. IR
Method A: A solution of crotonic acid (1f; 85.94 mg, 0.10 mmol)
and DTBP (73.55 mg, 0.50 mmol) in 2-propanol (2a; 50 mL) was
prepared. Photolysis was conducted three times using 10 mL of the
solution each time. Irradiation time: 3 h. Yield according to NMR,
run 1: 51% (conversion: Ͼ 99%, dimers 5f-1 + 5f-2: 24%, dimer
5f-3: 9%, dimer 5f-4: 6%), run 2: 49% (conversion: Ͼ 99%, dimers
5f-1 + 5f-2: 31%, dimer 5f-3: 11%, dimer 5f-4: 10%), run 3: 46%
(conversion: Ͼ 99%, dimers 5f-1 + 5f-2: 24%, dimer 5f-3: 11%,
dimer 5f-4: 12%). The crude products of runs 1–3 were combined
and purified. Eluent for chromatography: hexane/ethyl acetate
(KBr): ν = 2974, 2934, 2876, 1769, 1468, 1452, 1441, 1393, 1385,
˜
1373, 1356, 1342, 1325, 1287, 1267, 1231, 1219, 1196, 1179, 1136,
1121, 1067, 1051, 1026, 953, 934, 908, 881, 868, 824, 737, 679, 633,
606, 598, 588, 529, 501, 461, 439, 405 cm–1. MS (EI): m/z = 53 (20),
55 (44), 57 (18), 59 (16), 67 (35), 69 (31), 70 (52), 77 (11), 79 (16),
81 (24), 82 (11), 83 (30), 95 (33), 109 (100), 110 (16), 111 (12), 113
(13), 123 (26), 124 (36), 125 (24), 127 (52), 128 (57), 140 (38), 141
(10), 151 (17), 193 (12), 221 (12), 239 (19), 254 (2) [M]+, 255 (4)
[M + 1]+.
1
(99:1 Ǟ 3:1). Isolated yield of 4f: 33.4 mg (44%). Colorless oil. H
NMR (400 MHz, CDCl3): δ = 1.07 (d, J = 6.9 Hz, 3 H), 1.26 (s, 3
H), 1.43 (s, 3 H), 2.27 (dd, J = 16.3, 10.3 Hz, 1 H), 2.36 (ddq, J =
10.3, 7.3, 6.9 Hz, 1 H), 2.64 (dd, J = 16.3, 7.3 Hz, 1 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 14.2, 21.5, 27.0, 36.7, 39.8, 86.9,
Data for 5f-4: White powder, m.p. 165.5–166 °C. 1H NMR
(400 MHz, CDCl3): δ = 1.09 (d, J = 6.8 Hz, 3 H), 1.16 (d, J =
7.7 Hz, 3 H), 1.26 (s, 3 H), 1.43 (s, 3 H), 1.44 (s, 3 H), 1.48 (s, 3
H), 2.47 (dd, J = 9.6, 7.7 Hz, 1 H), 2.56 (dd, J = 12.9, 1.4 Hz, 1
H), 2.66 (dd, J = 12.9, 6.8 Hz, 1 H), 3.08 (dd, J = 9.6, 1.4 Hz, 1
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 12.7, 12.7, 21.5, 23.6,
27.1, 28.7, 41.9, 42.1, 44.8, 44.8, 85.0, 85.7, 174.9, 175.8 ppm. IR
175.7 ppm. IR (liquid film): ν = 2976, 2936, 2882, 1771, 1456, 1423,
˜
1391, 1375, 1273, 1260, 1231, 1175, 1132, 1113, 1084, 1040, 1018,
962, 934, 918, 833, 727, 667, 637, 598, 544, 525, 500 cm–1. MS (EI):
m/z = 55 (13), 59 (100), 69 (60), 70 (24), 84 (22), 85 (11), 95 (13),
113 (59), 128 (11) [M + 1]+. The mixture of the four dimers 5f-1–5f-
4[14a] was also isolated, 33 mg (43%). The four dimers were further
purified and isolated.
(KBr): ν = 2982, 2936, 2897, 1749, 1470, 1387, 1377, 1358, 1335,
˜
1314, 1265, 1229, 1211, 1196, 1179, 1148, 1132, 1096, 1072, 1109,
1030, 961, 947, 932, 908, 889, 804, 785, 752, 733, 679, 650, 606,
592, 571, 532, 503, 480, 432 cm–1. MS (EI): m/z = 53 (25), 55 (54),
57 (21), 59 (15), 67 (41), 69 (39), 70 (75), 77 (12), 79 (19), 81 (26),
82 (14), 83 (33), 91 (10), 95 (38), 109 (100), 110 (11), 123 (27), 124
(39), 125 (25), 127 (22), 128 (31), 140 (33), 141 (11), 151 (19), 193
(9), 239 (9), 254 (1) [M]+, 255 (1) [M + 1]+. HRMS (EI): calcd. for
C14H22O4 254.1518; found 254.1467.
Method B: Crotonic acid (1f; 22.46 mg, 0.26 mmol) and DTBP
(18.29 mg, 0.13 mmol) in 2-propanol (2a; 25 mL) was prepared.
Photolysis was conducted using 10 mL of the solution. Irradiation
time: 3 h. Yield according to NMR: 57% (conversion: Ͼ 99%, di-
mers 5f-1 + 5f-2: 22%, dimer 5f-3: 10%, dimer 5f-4: 5%).
Method C: Crotonic acid (1f; 22.46 mg, 0.26 mmol) and DTBP
(18.29 mg, 0.13 mmol) in 2-propanol (2a; 25 mL) was prepared. A
portion (5 mL) of the solution was diluted to 10 mL with 2-prop-
anol, and the resulting solution was subjected to photolysis. Irradi-
ation time: 3 h. Yield according to NMR: 56% (conversion:
Ͼ 99%, dimers 5f-1 + 5f-2: 13%, dimer 5f-3: 5%, dimer 5f-4: 4%).
Data for 5f-1: White powder, m.p. 179.5–180 °C. 1H NMR
(400 MHz, CDCl3): δ = 1.02 (d, J = 6.8 Hz, 6 H), 1.28 (s, 6 H),
1.48 (s, 6 H), 2.41 (dd, J = 12.8, 6.8 Hz, 2 H), 2.82 (d, J = 12.8 Hz,
2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 12.6, 21.4, 27.0, 41.9,
44.2, 85.4, 175.7 ppm. IR (KBr): ν = 2986, 2976, 2928, 2884, 2853,
˜
1767, 1474, 1385, 1371, 1329, 1308, 1263, 1236, 1221, 1177, 1136,
1121, 1074, 1042, 961, 947, 934, 908, 889, 725, 669, 638, 588, 577,
501, 405 cm–1. MS (EI): m/z = 53 (27), 55 (49), 57 (19), 59 (13), 67
(44), 69 (34), 70 (33), 77 (14), 79 (21), 81 (27), 82 (11), 83 (23), 91
(12), 95 (30), 109 (100), 110 (11), 123 (28), 124 (38), 125 (18), 127
(32), 128 (28), 140 (14), 151 (14), 254 (0.7) [M]+, 255 (1) [M + 1]+.
2-(1-Hydroxy-1-methylethyl)succinonitrile (3g): (i) A solution of
fumaronitrile (1e; 37.65 mg, 0.48 mmol) and DTBP (37.71 mg,
0.26 mmol) in 2-propanol (2a; 25 mL) was prepared. Photolysis
was conducted using 10 mL of the solution. Irradiation time: 1 h.
Yield according to NMR, run 1: 91% (conversion: Ͼ 99%). (ii)
A solution of fumaronitrile (1e; 37.01 mg, 0.47 mmol) and DTBP
(37.11 mg, 0.25 mmol) in 2-propanol (2a; 25 mL) was prepared.
Photolysis was conducted twice using 10 mL of the solution each
time. Irradiation time: 1 h. Yield according to NMR, run 2: 90%
(conversion: Ͼ 99%), run 3: 91% (conversion: Ͼ 99%). (iii) The
crude products of runs 1–3 were combined and purified. Eluent for
chromatography: hexane/ethyl acetate (7:1 Ǟ 5:1). Isolated yield:
68 mg (86%). Pale brown oil. 1H NMR (500 MHz, CDCl3): δ =
1.44 (s, 6 H), 2.39 (br. s, 1 H), 2.79 (dd, J = 17.0, 9.1 Hz, 1 H),
2.90 (dd, J = 17.0, 5.1 Hz, 1 H), 2.98 (dd, J = 9.1, 5.1 Hz, 1 H)
Data for 5f-2: White powder, m.p. 150–151 °C. 1H NMR
(400 MHz, CDCl3): δ = 1.11 (d, J = 6.8 Hz, 6 H), 1.27 (s, 6 H),
1.46 (s, 6 H), 2.29 (ddd, J = 14.2, 6.8, 1.8 Hz, 2 H), 2.81 (dd, J =
14.2, 1.8 Hz, 2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 13.7,
21.7, 27.1, 42.5, 45.6, 85.2, 175.0 ppm. IR (KBr): ν = 2976, 2941,
˜
2884, 2851, 1765, 1476, 1460, 1393, 1375, 1317, 1306, 1265, 1254,
1240, 1227, 1196, 1180, 1132, 1125, 1080, 1069, 1043, 964, 951,
908, 897, 880, 725, 664, 638, 610, 588, 571, 503, 467 cm–1. MS (EI):
m/z = 53 (20), 55 (49), 57 (20), 59 (15), 67 (34), 69 (32), 70 (59), 77
(10), 79 (16), 81 (24), 82 (15), 83 (65), 95 (38), 109 (100), 110 (12), ppm. 13C NMR (125 MHz, CDCl3): δ = 16.4, 26.5, 28.1, 40.8, 70.8,
111 (12), 113 (14), 123 (28), 124 (47), 125 (28), 127 (32), 128 (81),
140 (45), 141 (16), 151 (17), 193 (12), 221 (12), 239 (13), 254 (0.2)
[M]+, 255 (5) [M + 1]+.
116.8, 117.9 ppm. IR (liquid film): ν = 3465, 2982, 2943, 2884,
˜
2249, 1634, 1470, 1423, 1383, 1273, 1196, 1146, 1055, 1013, 966,
935, 907, 881, 864, 822, 781, 685, 596, 503 cm–1. MS (EI): m/z =
Eur. J. Org. Chem. 2013, 3807–3816
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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