Generation of [5.5.n] Tricyclic Ring Systems
J . Org. Chem., Vol. 62, No. 14, 1997 4607
46.6, 37.8; IR (neat) 1743-1719 (bs), 1260 (s), 1100 (s) cm-1
HRMS m/ z calcd for C12H14O4 222.0892, found 222.0889.
;
37.8, 29.0, 27.3, 27.0; diastereomer 3 (20%), δ 175.0, 135.4,
127.4, 58.8, 54.5, 51.0, 48.4, 47.7, 43.0, 37.8, 34.9, 28.6, 26.6;
diastereomer 4 (18%), δ 176.6, 132.2, 128.6, 56.6, 53.4, 51.5,
50.3, 48.6, 46.8, 37.3, 30.4, 28.6, 26.5; IR (neat) 1736 (s), 1196
(s), 1169 (s) cm-1; HRMS m/ z calcd for C13H18O2 206.1307,
found 206.1307.
Meth yl 2,3,3a ,3b,6,6a ,7,7a -Octa h yd r o-3-oxo-1H-cyclo-
p en ta [a ]p en ta len e-7-ca r boxyla te (13). The cyclopropyl
ester 3 (0.50 g, 3.62 mmol), cyclopentenone (1.19 g, 14.50
mmol), and n-butyl disulfide (0.52 g, 2.90 mmol) were com-
bined in 5 mL of degassed benzene. After 4 days of photolysis,
chromatography afforded 0.66 g (83%) of 13 as a colorless oil
consisting of three partially separable diastereomers in a ratio
of 1.2:1.1:1.0: 1H NMR (CDCl3) (diastereomeric mixture) δ
5.65-5.62 (m, 2 H), 3.72 (s, 1.1 H), 3.71 (s, 1.0 H), 3.69 (s, 0.9
H), 3.10-1.57 (m, 11 H); 13C NMR (CDCl3) diastereomer 1
(36%), δ 221.1, 174.5, 134.6, 129.4, 57.7, 55.3, 54.8, 52.4, 45.7,
43.3, 40.0, 38.5, 24.1; diastereomer 2 (34%), δ 221.8, 174.2,
135.3, 130.9, 60.2, 57.7, 53.7, 53.2, 45.6, 42.6, 38.1, 36.1, 23.2;
diastereomer 3 (31%), δ 221.6, 173.9, 132.4, 131.3, 57.7, 57.6,
52.4, 52.2, 47.1, 43.4, 41.3, 39.5, 25.1; IR (neat) 1732 (bs), 1169
(bs) cm-1; HRMS m/ z calcd for C13H16O3 220.1100, found
220.1100.
Meth yl 2,3,3a ,4,4a ,5,7a ,7b-Octa h yd r op en ta len o[1,2-b]-
fu r a n -4-ca r boxyla te (14). The cyclopropyl ester 3 (0.075 g,
0.54 mmol), 2,3-dihydrofuran (0.31 g, 4.34 mmol), and n-butyl
disulfide (0.064 g, 0.36 mmol) were combined in 1.5 mL of
degassed benzene and photolyzed for 7 days. Purification
afforded 0.094 g (83%) of 14 as four partially separable
diastereomers in a ratio of 2.0:1.7:1.0:1.0: 1H NMR (CDCl3)
diastereomers 1-3 (inseparable mixture, 70%), δ 5.74-5.56
(m, 2 H), 3.98-3.76 (m, 2 H), 3.68 (s, 3 H), 3.60-1.58 (m, 9
H); diastereomer 4 (30%), δ 5.72 (m, 1 H), 5.65 (m, 1 H), 4.54
(t, J ) 8.0 Hz, 1 H), 3.94 (dt, J ) 2.0, 8.3 Hz, 1 H), 3.70 (s, 3
H), 3.68 (m, 2 H), 3.26-1.65 (m, 7 H); 13C NMR (CDCl3)
diastereomer 1 (35%), δ 174.2, 131.1, 130.6, 89.1, 67.3, 56.3,
52.7, 51.4, 44.8, 44.7, 35.5, 29.8; diastereomer 2 (18%), δ 174.2,
129.5, 129.0, 86.8, 68.0, 55.0, 54.8, 51.7, 49.8, 44.8, 37.9, 30.5;
diastereomer 3 (17%), δ 173.6, 131.0, 130.5, 85.3, 70.6, 54.2,
51.3, 47.3, 46.6, 43.3, 38.0, 29.5; diastereomer 4 (30%), δ 175.6,
132.2, 129.6, 85.7, 68.4, 58.5, 52.7, 47.8, 46.2, 41.8, 37.6, 29.3;
IR (neat) 1736 (s), 1175 (bs), 1063 (m) cm-1; HRMS m/ z calcd
for C12H16O3 208.1100, found 208.1101.
Meth yl 3b-(Acetyloxy)-3a ,3b,4,5,6,6a ,7,7a -octa h yd r o-
1H-cyclop en ta [a ]p en ta len e-7-ca r boxyla te (15). The cy-
clopropyl ester 3 (0.080 g, 0.58 mmol), 1-(acetyloxy)cyclopen-
tene21 (0.73 g, 5.79 mmol), and n-butyl disulfide (0.023 g, 0.13
mmol) were combined in 2 mL of degassed benzene. After 2
weeks of photolysis, the reaction was worked up as above to
yield 0.024 g of recovered starting material and 0.075 g of 15
(70% based on recovered starting material) as a colorless oil
consisting of three inseparable diastereomers in a ratio of
1.9:1.6:1.0: 1H NMR (CDCl3) (diastereomeric mixture) δ 5.69
(m, 1 H), 5.63 (m, 1 H), 3.69 (s, 3 H), 2.03 (s, 0.7 H), 2.01 (s,
1.2 H), 2.00 (s, 1.1 H), 3.10-1.20 (m, 12 H); 13C NMR (CDCl3)
diastereomer 1 (43%), δ 174.6, 171.4, 131.9, 131.2, 100.4, 60.6,
55.9, 52.0, 51.0, 44.8, 38.7, 34.3, 28.1, 25.6, 23.4; diastereomer
2 (35%), δ 174.4, 171.6, 132.8, 132.2, 99.5, 60.3, 57.4, 54.0, 52.1,
48.0, 43.9, 37.3, 28.8, 26.0, 22.8; diastereomer 3 (22%), δ 176.0,
175.0, 132.0, 131.1, 99.3, 61.8, 56.7, 52.6, 46.8, 40.9, 38.3, 34.9,
28.5, 25.8, 22.5; IR (neat) 1736 (s), 1190 (bs) cm-1; HRMS m/ z
calcd for C15H20O4 264.1362, found 264.1355.
4-Eth en yl-5-eth oxy-1,2,3,3a,4,5,6,6a-Octah ydr open talen -
1-on e (17). The cyclopropyl ketone 4 (0.060 g, 0.49 mmol),
ethyl vinyl ether (0.53 g, 7.37 mmol), and n-butyl disulfide
(0.013 g, 0.074 mmol) were combined in 1 mL of degassed
benzene. After 4 days of photolysis, purification afforded 0.063
g (66%) of 17 as a colorless oil consisting of four diastereomers
in a ratio of 1.4:1.2:1.0:1.0: 1H NMR (CDCl3) diastereomer 1
(30%), δ 5.74 (ddd, J ) 7.2, 10.2, 17.2 Hz, 1 H), 5.14 (d, J )
17.2 Hz, 1 H), 5.06 (d, J ) 10.2 Hz, 1 H), 3.45 (q, J ) 6.5 Hz,
2 H), 3.00-1.10 (m, 13 H); diastereomer 2 (22%), δ 5.87 (ddd,
J ) 3.0, 10.2, 17.2 Hz, 1 H), 5.14 (d, J ) 17.2 Hz, 1 H), 5.06
(d, J ) 10.2 Hz, 1 H), 3.38 (q, J ) 6.8 Hz, 2 H), 3.00-1.10 (m,
13 H); diastereomer 3 (26%), δ 5.94 (ddd, J ) 7.2, 11.1, 18.4
Hz, 1 H), 5.11 (d, J ) 18.4 Hz, 1 H), 5.03 (d, J ) 11.1 Hz, 1 H),
3.36 (q, J ) 6.8 Hz, 2 H), 3.00-1.10 (m, 13 H); diastereomer
4 (22%), δ 5.75 (ddd, J ) 7.2, 11.1, 18.4 Hz, 1 H), 5.11 (d, J )
18.4 Hz, 1 H), 5.03 (d, J ) 11.1 Hz, 1 H), 3.45 (q, J ) 6.8 Hz,
2 H), 3.00-1.10 (m, 13 H); 13C NMR (CDCl3) diastereomer 1,
δ 213.8, 139.6, 116.1, 90.9, 66.0, 59.5, 54.9, 51.9, 43.0, 28.8,
25.7, 16.1; diastereomer 2, δ 222.8, 136.9, 118.0, 83.1, 66.0,
53.7, 48.9, 43.1, 39.7, 34.8, 23.6, 16.2; diastereomer 3, δ 224.2,
140.0, 116.3, 85.8, 65.3, 55.3, 49.7, 44.6, 36.6, 34.8, 24.9, 16.1;
diastereomer 4, δ 223.3, 137.7, 117.0, 85.0, 65.6, 56.6, 51.0,
45.4, 36.8, 35.3, 23.2, 14.5; IR (neat) 1740 (s), 1119 (bs) cm-1
;
HRMS m/ z calcd for C12H18O2 194.1307, found 194.1310.
7-E t h en yl-2,3,3a ,3b ,4,5,6,6a ,7,7a -d eca h yd r o-3(1H )-cy-
clop en ta [a ]p en ta len on e (18). The cyclopropyl ketone 4
(0.20 g, 1.64 mmol) and cyclopentene (2.24 g, 32.78 mmol) were
combined with n-butyl disulfide (0.18 g, 0.98 mmol) in 6 mL
of benzene. After 2 weeks of photolysis, the reaction was 40%
complete. Concentration and chromatography gave the adduct
18 (0.085 g, 68% based on unreacted starting material) as a
colorless oil consisting of four partially separable diastereomers
in a ratio of 2.0:1.9:1.2:1.0: 1H NMR (CDCl3) diastereomers
1-2 (47%), δ 5.80 (ddd, J ) 7.8, 10.4, 17.0 Hz, 1 H), 5.07 (ddd,
J ) 0.9, 1.9, 10.4 Hz, 1 H), 5.03 (ddd, J ) 1.0, 1.9, 17.0 Hz, 1
H), 2.68-1.24 (m, 15 H); diastereomer 3-4 (53%), δ 5.77 (ddd,
J ) 7.6, 10.3, 17.1 Hz, 1 H), 5.05 (ddd, J ) 1.0, 1.8, 17.1 Hz,
1 H), 4.98 (ddd, J ) 0.8, 1.8, 10.3 Hz, 1 H), 2.75-1.23 (m, 15
H); 13C NMR (CDCl3) diastereomer 1 (31%), δ 222.8, 138.5,
115.5, 61.4, 51.2, 50.0, 45.2, 44.4, 35.2, 34.9, 27.3, 25.0, 21.3;
diastereomer 2 (16%), δ 219.6, 136.1, 126.7, 57.2, 51.2, 44.3,
39.6, 38.4, 33.6, 31.4, 29.5, 25.0, 21.9; diastereomer 3 (33%), δ
213.1, 140.4, 114.2, 66.5, 53.5, 53.4, 42.8, 31.8, 30.8, 25.1, 25.0,
24.3, 21.9; diastereomer 4 (20%), δ 219.7, 136.1, 126.7, 57.2,
56.5, 44.3, 39.6, 37.2, 33.6, 30.3, 29.6, 28.0, 24.6; IR (neat) 1734
(s), 1154 (w) cm-1; HRMS m/ z calcd for C13H18O 190.1358,
found 190.1357.
3a ,3b ,4,5,6,6a ,7,7a -O c t a h y d r o -1H -c y c lo p e n t a [a ]-
p en ta len e-7-ca r boxa ld eh yd e (19). A solution of the ester
16 (0.60 g, 2.91 mmol) in 10 mL of ether was added to DIBAL
(9.47 mL of a 1 M solution in hexane, 9.47 mmol) in 20 mL of
ether. The resulting solution was stirred for 2 h and quenched
with 1 M NaOH solution. The organic layer was decanted,
washed with water, and evaporated. The residual oil (0.48 g,
2.69 mmol) was dissolved in 40 mL of dichloromethane. PCC
(0.70 g, 3.26 mmol) and Celite (0.75 g) were added, and the
mixture was stirred at room temperature for 3 h. Ether was
added, and the reaction mixture was filtered through a pad of
Florisil. The resulting solution was concentrated to afford the
aldehyde 19 (0.37 g, 72%) as a colorless oil. The product was
a mixture of four diastereomers in a ratio of 1.9:1.5:1.3:1.0:
1H NMR (CDCl3) (diastereomeric mixture) δ 9.81 (d, J ) 2.0
Hz, 0.34 H), 9.80 (d, J ) 2.9 Hz, 0.18 H), 9.64 (d, J ) 2.8 Hz,
0.25 H), 9.60 (d, J ) 3.8 Hz, 0.23 H), 5.73-5.50 (m, 2 H), 3.15-
1.26 (m, 13 H); 13C NMR (CDCl3) diastereomer 1 (33%), δ
205.3, 136.0, 129.7, 62.3, 50.9, 46.4, 38.4, 34.9, 34.9, 34.6, 31.8,
26.5; diastereomers 2-4 (67%, indistinguishable), δ 206.6(2
C), 205.3, 136.1, 133.8, 133.0, 131.0, 129.6, 128.4, 65.9, 63.5,
60.1, 58.9, 58.3, 54.6, 54.5, 49.9, 49.8, 48.4, 48.1, 47.9, 47.1,
46.5, 45.5, 41.7, 37.8, 36.8, 34.9, 31.0, 29.4, 29.0, 28.7, 28.6,
Met h yl 3a ,3b,4,5,6,6a ,7,7a -Oct a h yd r o-1H-cyclop en t a -
[a ]p en ta len e-7-ca r boxyla te (16). The cyclopropyl ester 3
(0.40 g, 2.89 mmol), cyclopentene (4.94 g, 72.40 mmol), and
n-butyl disulfide (0.33 g, 1.81 mmol) were combined in 10 mL
of degassed benzene. After 2 weeks of photolysis, the reaction
was 50% complete; further photolysis had no effect. Chro-
matographic purification afforded recovered starting material
and 0.18 g (33%; 66% based on unreacted starting material)
of 16. The product was a colorless oil consisting of four
partially separable diastereomers in a ratio of 1.8:1.6:1.1:1.0:
1H NMR (CDCl3) (diastereomeric mixture) δ 5.68-5.53 (m, 2
H), 3.68 (s, 1.16 H), 3.67 (s, 1.84 H), 2.75-1.25 (m, 13 H); 13
C
NMR (CDCl3) diastereomer 1 (33%), δ 174.9, 134.3, 128.7, 56.5,
53.8, 50.9, 46.3, 45.7, 37.8, 35.2, 33.0, 30.3, 25.2; diastereomer
2 (29%), δ 174.4, 132.4, 130.4, 52.9, 51.2, 49.8, 49.1, 46.8, 44.9,
(21) J ones, R. A.; Stokes, M. J . Tetrahedron 1984, 40, 1051.
(22) Ohta, S.; Shimabayashi, A.; Aono, M.; Okamoto, M. Synthesis
1982, 833.