1986
G. Molteni, P. Del Buttero / Tetrahedron: Asymmetry 16 (2005) 1983–1987
each signal) 1.8 s. Optical rotations were recorded on a
Perkin–Elmer 241 polarimeter at the sodium D-line.
Compounds 1 and 2 were used as purchased from Al-
drich. Compounds 3,6 99 and 1011 were prepared accord-
ing to the literature procedures.
4.2.2. Compound 8. 0.37 g, 96%. White powder; mp
25
79 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ107.2 (c
D
1
0.40, CHCl3); IR (Nujol) 1735, 1730 cmꢀ1; H NMR
(CDCl3) d 0.96 (3H, s), 1.25 (3H, s), 1.80–2.50 (6H, m),
3.70 (1H, dd, J 11.5, 5.0), 3.90 (3H, s), 4.21 (2H, AB, J
13.3), 5.74 (1H, dd, J 12.4, 2.1), 5.98 (1H, dd, J 18.2,
12.4), 6.27 (1H, dd, J 18.2, 2.1), 7.2–7.3 (5H, m); MS
m/z 382 (M+). Anal. Calcd for C22H26N2O3: C, 69.09;
H, 6.85; N, 7.32. Found: C, 69.06; H, 6.87; N, 7.28.
4.1. Cycloaddition between hydrazonoyl chloride 3 and
pinane derivatives 1 and 2
A solution of hydrazonoyl chloride 3 (0.53 g, 2.5 mmol)
and the appropriate pinane derivative 1 or 2 (0.26 g,
1.7 mmol) in dry toluene (25 mL) was treated with tri-
ethylamine (1.26 g, 12.5 mmol) and refluxed for 48 h.
The crude was evaporated under reduced pressure and
the residue chromatographed on a silica gel column with
ethyl acetate–hexane–dichloromethane 10:2:1. The first
fractions contained the starting pinane derivative 1 or
2 in a 10–15% amount, followed by decomposition
products of hydrazonoyl chloride 3. Further elution
gave cycloadducts 5 and 6.
4.3. Cycloadditions between acrylates 7 and 8 and
hydrazonoyl chloride 9
A solution of 7 or 8 (0.46 g, 1.2 mmol) and hydrazonoyl
chloride 9 (0.34 g, 1.5 mmol) in dry toluene (12 mL) was
treated with triethylamine (0.61 g, 6.0 mmol) and re-
fluxed for 24 h. The crude was evaporated under re-
duced pressure and the residue was chromatographed
on a silica gel column with hexane–ethyl acetate–dichlo-
romethane 3:1:1. Major diastereoisomer 11 or 13 was
eluted first, followed from minor 12 or 14.
4.1.1. Compound 5. 0.26 g, 47%. Pale yellow powder;
25
D
1
mp 83 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ37.4 (c
4.3.1. Compound 11. 0.43 g, 62%. Pale yellow powder;
25
0.24, CHCl3); IR (Nujol) 3460, 1735 cmꢀ1; H NMR
(CDCl3) d 1.20 (3H, s), 1.36 (3H, s), 1.37 (3H, s), 2.10–
2.60 (4H, m), 3.20 (1H, br s), 3.28 (1H, d, J 4.2), 3.89
(3H, s), 4.12 (1H, dd, J 10.4, 4.2), 7.1–7.3 (5H, m); MS
m/z 328 (M+). Anal. Calcd for C19H24N2O3: C, 69.49;
H, 7.37; N, 8.53. Found: C, 69.53; H, 7.40; N, 8.57.
mp 111 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ48.8 (c
D
1
0.22, CHCl3,); IR (Nujol) 1740, 1730 cmꢀ1; H NMR
(CDCl3) d 1.16 (3H, s), 1.34 (3H, s), 1.46 (3H, s), 2.25
(3H, s), 2.30–2.50 (4H, m), 3.28 (1H, dd, J 12.8, 7.4),
3.54 (1H, dd, J 12.8, 9.6), 3.71 (1H, d, J 4.5), 3.88
(3H, s), 3.92 (3H, s), 4.86 (1H, dd, J 9.6, 7.4), 5.12
(1H, dd, J 10.2, 4.5), 7.1–7.4 (9H, m); MS m/z 572
(M+). Anal. Calcd for C32H36N4O6: C, 67.12; H, 6.34;
N, 9.78. Found: C, 67.09; H, 6.30; N, 9.83.
4.1.2. Compound 6. 0.33 g, 59%. Pale yellow powder;
25
mp 96 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ65.4 (c
D
1
0.31, CHCl3); IR (Nujol) 3450, 1730 cmꢀ1; H NMR
(CDCl3) d 0.95 (3H, s), 1.27 (3H, s), 1.80–2.50 (6H,
m), 3.40 (1H, br s), 3.61 (1H, d, J 12.7), 3.72 (1H, dd,
J 11.5, 5.1), 3.81 (3H, s), 3.87 (1H, d, J 12.7), 7.2–7.3
(5H, m); MS m/z 328 (M+). Anal. Calcd for
C19H24N2O3: C, 69.49; H, 7.37; N, 8.53. Found: C,
69.52; H, 7.34; N, 8.49.
4.3.2. Compound 12. 0.13 g, 19%. White powder; mp
25
89 ꢁC (from diisopropyl ether); ½aꢁ ¼ þ16.3 (c 0.30,
D
CHCl3); IR (Nujol) 1740, 1730 cmꢀ1; 1H NMR (CDCl3)
d 1.14 (3H, s), 1.33 (3H, s), 1.40 (3H, s), 2.28 (3H, s),
2.30–2.50 (4H, m), 3.22 (1H, dd, J 12.8, 7.0), 3.50 (1H,
dd, J 12.8, 9.4), 3.74 (1H, d, J 4.5), 3.85 (3H, s), 3.90
(3H, s), 4.90 (1H, dd, J 9.4, 7.0), 5.10 (1H, dd, J 10.2,
4.5), 7.1–7.4 (9H, m); MS m/z 572 (M+). Anal. Calcd
for C32H36N4O6: C, 67.12; H, 6.34; N, 9.78. Found: C,
67.10; H, 6.31; N, 9.84.
4.2. Reaction between bicyclo[3.1.1]heptano[4,5-c]pyraz-
oles 5,6 and acriloyl chloride
A solution of 5 or 6 (0.33 g, 1.0 mmol) in dry toluene
(12 mL) was treated with triethylamine (0.12 g,
1.2 mmol) and acriloyl chloride (0.11 g, 1.2 mmol) and
refluxed for 30 h. The crude was evaporated under re-
duced pressure and the residue taken up with chloro-
form (25 mL). The mixture was filtered and the
organic layer washed with 5% sodium hydrogencarbon-
ate (2 · 20 mL), dried over sodium sulfate and evapo-
rated. The residue was crystallized from diisopropyl
ether affording pure acrylates 7 and 8.
4.3.3. Compound 13. 0.30 g, 52%. White powder; mp
25
58 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ49.6 (c
D
1
0.30, CHCl3); IR (Nujol) 1740, 1730 cmꢀ1; H NMR
(CDCl3) d 0.96 (3H, s), 1.28 (3H, s), 1.80–2.50 (6H, m),
2.28 (3H, s), 3.11 (1H, dd, J 12.6, 7.5), 3.44 (1H, dd, J
12.6, 9.5), 3.54 (1H, dd, J 11.3, 4.5), 3.84 (3H, s), 3.89
(3H, s), 3.93 (1H, d, J 12.5), 4.32 (1H, d, J 12.5), 4.83
(1H, dd, J 9.5, 7.5), 7.0–7.5 (9H, m); MS m/z 572 (M+).
Anal. Calcd for C32H36N4O6: C, 67.12; H, 6.34; N,
9.78. Found: C, 67.13; H, 6.36; N, 9.81.
4.2.1. Compound 7. 0.36 g, 94%. White powder; mp
25
D
1
76 ꢁC (from diisopropyl ether); ½aꢁ ¼ ꢀ98.5 (c
4.3.4. Compound 14. 0.15 g, 22%. White powder; mp
25
0.44, CHCl3); IR (Nujol) 1740, 1730 cmꢀ1; H NMR
(CDCl3) d 1.18 (3H, s), 1.38 (3H, s), 1.49 (3H, s), 2.25–
2.60 (4H, m), 3.54 (1H, d, J 4.5), 3.85 (3H, s), 5.24 (1H,
dd, J 11.0, 4.5), 5.86 (1H, dd, J 12.1, 2.2), 6.18 (1H, dd,
J 18.6, 12.1), 6.47 (1H, dd, J 18.6, 2.2), 7.2–7.3 (5H, m);
MS m/z 382 (M+). Anal. Calcd for C22H26N2O3: C,
69.09; H, 6.85; N, 7.32. Found: C, 69.13; H, 6.88; N, 7.36.
79 ꢁC (from diisopropyl ether); ½aꢁ ¼ þ17.5 (c
D
1
0.11, CHCl3); IR (Nujol) 1735, 1730 cmꢀ1; H NMR
(CDCl3) d 0.94 (3H, s), 1.23 (3H, s), 1.80–2.50 (6H, m),
2.25 (3H, s), 3.17 (1H, dd, J 12.6, 7.5), 3.42 (1H, dd, J
12.6, 9.6), 3.54 (1H, dd, J 11.1, 4.5), 3.81 (3H, s), 3.90
(3H, s), 3.98 (1H, d, J 12.5), 4.30 (1H, d, J 12.5), 4.88
(1H, dd, J 9.6, 7.5), 7.0–7.5 (9H, m); MS m/z 572 (M+).