2334
Y. Oonishi et al.
PAPER
1H NMR (400 MHz, CDCl3): d = 1.39–1.46 (m, 2 H), 1.57–1.74 (m,
5 H), 1.80–1.87 (m, 1 H), 2.49 (ddd, J = 7.9, 4.1, 4.1 Hz, 1 H), 2.74–
2.79 (m, 1 H), 5.02 (d, J = 10.2 Hz, 1 H), 5.13 (d, J = 16.9 Hz, 1 H),
5.87 (dd, J = 15.2, 7.9 Hz, 1 H), 6.11 (dd, J = 15.2, 10.2 Hz, 1 H),
6.30 (dt, J = 16.9, 10.2 Hz, 1 H), 9.68 (s, 1 H).
13C NMR (100 MHz, CDCl3): d = 23.1, 23.6, 23.8, 30.4, 39.3, 52.4,
116.2, 131.8, 134.7, 136.9, 205.2.
J = 6.0, 6.0, 6.0 Hz, 2 H), 2.56 (dd, J = 6.3, 6.3 Hz, 2 H), 6.44 (dd,
J = 6.0, 6.0 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 21.7, 25.2, 26.5, 26.9, 27.6, 30.5,
33.4, 37.0, 37.7, 42.7, 140.4, 144.1, 204.9.
LRMS (EI): m/z = 220 [M+], 137, 125, 121, 110, 98, 95, 81.
HRMS (EI): m/z calcd for C15H24O: 220.1827; found: 220.1818.
LRMS (EI): m/z = 164 [M+], 149, 121, 109.
(E)-2-(4-Cyclohexylbutylidene)cyclopentanone (6b¢)
HRMS (EI): m/z calcd for C11H16O: 164.1201; found: 164.1199.
IR (neat): 2923, 1721, 1651, 1448 cm–1.
1H NMR (400 MHz, CDCl3): d = 0.84–0.86 (m, 2 H), 1.11–1.25 (m,
6 H), 1.55–1.69 (m, 7 H), 1.93 (dddd, J = 7.6, 7.6, 7.6, 7.6 Hz, 2 H),
2.11 (dt, J = 7.5, 7.5 Hz, 2 H), 2.33 (dd, J = 7.6, 7.6 Hz, 2 H), 2.56–
2.59 (m, 2 H), 6.54 (tdd, J = 7.5, 2.6, 2.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 21.7, 25.2, 26.5, 26.8, 27.6, 30.6,
33.4, 37.0, 37.8, 42.7, 140.4, 144.0, 204.9.
Cyclization of (4E,6E)-1a; Typical Procedure
A soln of [Rh(dppe)(nbd)]ClO4 (18.0 mg, 0.026 mmol) in degassed
DCE (1.0 mL) was stirred under a H2 atmosphere at r.t. for 1 h. The
reaction vessel was flushed with argon gas, and a soln of (4E,6E)-
7a (55.0 mg, 0.26 mmol) in degassed DCE (1.6 mL) was added to
the soln. The mixture was stirred at 65 °C for 18 h. After removal of
the solvent, the residue was purified by column chromatography
(silica gel) to afford 2a (62%) along with 6a (13%) and 6a¢ (6%).
All cyclization reactions were carried out by this procedure. The
spectral data of the new cyclized products are given below. The
spectral data of the known compounds cyclohept-3-enone (2e) and
(E)-2-ethylidenecyclopentanone [(E)-6e¢] are consistent with those
reported in the literature.22,23
LRMS (EI): m/z = 220 [M+], 177, 123, 110, 97, 84.
HRMS (EI): m/z calcd for C15H24O: 220.1827; found: 220.1827.
2-[(Benzyloxy)methyl]cyclohept-3-enone (2c)
IR (neat): 2933, 2858, 1705, 1456, 1362, 1112, 1027, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.76–1.84 (m, 1 H), 2.08–2.20 (m,
2 H), 2.46–2.56 (m, 2 H), 2.62–2.69 (m, 1 H), 3.56 (dd, J = 9.1, 7.0
Hz, 1 H), 3.87 (dd, J = 9.1, 7.0 Hz, 1 H), 3.97–4.02 (m, 1 H), 4.52
(d, J = 12.0 Hz, 1 H), 4.58 (d, J = 12.0 Hz, 1 H), 5.28 (dddd,
J = 11.1, 3.2, 1.8, 1.8 Hz, 1 H), 5.72–5.78 (m, 1 H), 7.27–7.34 (m,
5 H).
2-Phenethylcyclohept-3-enone (2a)
IR (neat): 3024, 2934, 1708, 1654, 1496, 1456 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.67–1.82 (m, 2 H), 2.03–2.18 (m,
3 H), 2.31–2.76 (m, 5 H), 3.61–3.66 (m, 1 H), 5.23 (dddd, J = 11.1,
3.2, 2.0, 2.0 Hz, 1 H), 5.76 (dddd, J = 11.1, 6.7, 6.7, 1.9 Hz, 1 H),
7.16–7.31 (m, 5 H).
13C NMR (100 MHz, CDCl3): d = 21.6, 39.8, 44.0, 49.9, 69.6, 73.5,
123.2, 127.4, 127.6, 128.1, 131.4, 137.9, 207.2.
LRMS (EI): m/z = 230 [M+], 139, 122, 108, 91, 79.
13C NMR (100 MHz, CDCl3): d = 21.8, 29.4, 31.8, 33.2, 44.0, 48.4,
125.7, 126.8, 128.2, 128.4, 131.2, 141.8, 208.9.
HRMS (EI): m/z calcd for C15H18O2: 230.1307; found: 230.1311.
LRMS (EI): m/z = 214 [M+], 123, 110, 104, 91.
2-[(Benzyloxy)methyl]cyclohept-2-enone (2c¢)
HRMS (EI): m/z calcd for C15H18O: 214.1358; found: 214.1346.
IR (neat): 2935, 2862, 1662, 1453, 1260, 1108, 796, 737, 698 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.75–1.82 (m, 4 H), 2.45–2.46 (m,
2 H), 2.61–2.64 (m, 2 H), 4.19 (s, 2 H), 4.55 (s, 2 H), 6.80 (dd,
J = 6.0, 6.0 Hz, 1 H), 7.26–7.35 (m, 5 H).
13C NMR (100 MHz, CDCl3): d = 21.5, 25.2, 27.8, 42.9, 69.7, 72.9,
127.5, 127.7, 128.3, 138.3, 139.8, 143.3, 203.8
(E)-2-(4-Phenylbut-1-enyl)cyclopentanone (6a)
IR (neat): 2960, 2854, 1740, 1453, 1149 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.68–1.88 (m, 2 H), 2.00–2.42 (m,
6 H), 2.68–2.76 (m, 3 H), 5.47 (dd, J = 15.6, 6.1 Hz, 1 H), 5.60 (dt,
J = 15.6, 6.3 Hz, 1 H), 7.17–7.38 (m, 5 H).
LRMS (EI): m/z = 230 [M+], 139, 124, 107, 91, 79.
13C NMR (100 MHz, CDCl3): d = 20.7, 29.8, 34.4, 35.7, 37.7, 52.2,
125.8, 126.6, 128.2, 128.4, 132.4, 141.8, 218.9.
HRMS (EI): m/z calcd for C15H18O2: 230.1307; found: 230.1310.
LRMS (EI): m/z = 214 [M+], 123, 110, 105, 91.
2-[3-(Benzyloxy)propylidene]cyclopentanone (6c¢)
HRMS (EI): m/z calcd for C15H18O: 214.1358; found: 214.1362.
IR (neat): 2925, 2862, 1718, 1649, 1260, 1108 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.93 (dddd, J = 7.8, 7.8, 7.8, 7.8
Hz, 2 H), 2.32 (dd, J = 7.8, 7.8 Hz, 2 H), 2.46 (dt, J = 6.2, 6.2 Hz, 2
H), 2.56–2.61 (m, 2 H), 3.58 (t, J = 6.2 Hz, 2 H), 4.51 (s, 2 H), 6.52–
6.59 (m, 1 H), 7.24–7.34 (m, 5 H).
(E)-2-(4-Phenylbutylidene)cyclopentanone (6a¢)
IR (neat): 2924, 2856, 1718, 1648, 1096 cm–1.
1H NMR (400 MHz, CDCl3): d = 1.81 (tt, J = 7.6, 7.6 Hz, 2 H), 1.93
(dddd, J = 7.6, 7.6, 7.6, 7.6 Hz, 2 H), 2.18 (dt, J = 7.6, 7.6, Hz, 2 H),
2.34 (dd, J = 7.6, 7.6 Hz, 2 H), 2.52–2.57 (m, 2 H), 2.67 (t, J = 7.6
Hz, 2 H), 6.57 (dddd, J = 7.6, 7.6, 2.7, 2.7 Hz, 1 H), 7.15–7.32 (m,
5 H).
LRMS (EI): m/z = 230 [M+], 139, 122, 107, 91, 77.
HRMS (EI): m/z calcd for C15H18O2: 230.1307; found: 230.1311.
13C NMR (100 MHz, CDCl3): d = 20.0, 26.9, 29.3, 30.1, 35.6, 38.7,
2-{2,2-Bis[(benzyloxy)methyl]-4-methylpent-4-enyl}cyclohept-
3-enone (2d)
125.7, 128.1 128.2, 135.4, 137.4, 141.5, 206.7.
IR (neat): 2930, 2858, 1710, 1453, 1097, 1028, 735, 698 cm–1.
LRMS (EI): m/z = 214 [M+], 130, 123, 110, 91.
1H NMR (400 MHz, CDCl3): d = 1.41–1.46 (m, 1 H), 1.76 (s, 3 H),
1.90–1.92 (m,1 H), 2.03–2.22 (m, 4 H), 2.28–2.47 (m, 4 H), 3.20–
3.41 (m, 4 H), 3.99–4.02 (m, 1 H), 4.33–4.46 (m, 4 H), 4.69 (s, 1 H),
4.86 (s, 1 H), 5.13 (dddd, J = 11.1, 3.2, 2.0, 2.0 Hz, 1 H), 5.60 (dddd,
J = 11.1, 6.7, 6.7, 1.9 Hz, 1 H), 7.26–7.34 (m, 10 H).
HRMS (EI): m/z calcd for C15H18O: 214.1358; found: 214.1365.
2-(2-Cyclohexylethyl)cyclohept-2-enone (2b¢)
IR (neat): 2924, 2856, 1718, 1648, 1260, 1096, 800, 698 cm–1.
1H NMR (400 MHz, CDCl3): d = 0.85–0.90 (m, 2 H), 1.10–1.25 (m,
6 H), 1.61–1.78 (m, 9 H), 2.23 (t, J = 7.6 Hz, 2 H), 2.35 (ddd,
Synthesis 2007, No. 15, 2323–2336 © Thieme Stuttgart · New York