Synthesis of highly functionalized pentalenes via intermolecular Pauson-Khand reaction

Article abstract of DOI:10.1002/ejoc.200500966

A concise synthetic route to highly substituted pentalenones 4 and 5, respectively, is reported. The key step is a Pauson-Khand reaction of norbornadiene (7) with the functionalized acetylenes 8 to give the methanoindenone derivatives 6. 1,4-Addition of o

Full text of DOI:10.1002/ejoc.200500966

FULL PAPER
DOI: 10.1002/ejoc.200500966
Synthesis of Highly Functionalized Pentalenes via Intermolecular
Pauson–Khand Reaction
Armand Becheanu,[a] Angelika Baro,[a] Sabine Laschat,*[a] and Wolfgang Frey[a]
Dedicated to Prof. Siegfried Hünig on the occasion of his 85th birthday
Keywords: Acetylation / Lipases / Organocuprate addition / Pauson–Khand reaction / Pentalenes
A concise synthetic route to highly substituted pentalenones
4 and 5, respectively, is reported. The key step is a Pauson–
Khand reaction of norbornadiene (7) with the functionalized
acetylenes 8 to give the methanoindenone derivatives 6. 1,4-
Addition of organocuprates resulted in clean formation of
lenones 10 were obtained in moderate to good yields. A dif-
ferentiation of the hydroxy groups became possible by li-
pase-mediated acetylation with vinyl acetate, giving highly
selectively monoacetates 4 with the acetyl group at C-6 of
the pentalene system.
2,3-trans-disubstituted methanoindenones 9. After ozonoly- (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
sis and reductive workup, the bis(hydroxymethyl)penta-
Germany, 2006)
8 seemed to be attractive because the resulting tricyclic cy-
clopentenone 6 can be manipulated by conjugate cuprate
addition and furthermore, the alkene moiety can be cleaved
oxidatively. We anticipated that subsequent esterification
should allow a differentiation between the two hydroxy
groups, thus giving access to pentasubstituted bicyclo[3.3.0]-
octanes 4 or 5 in a stereoselective fashion (Scheme 2). The
results towards this goal are reported below.
Introduction
Pentalenes, i.e., bicyclo[3.3.0]octanes, constitute impor-
tant building blocks of many natural products and pharma-
cologically active compounds such as carbacyclin (1) and
triquinanes 2, 3 (Scheme 1). Thus, a lot of efforts has been
spent on the synthesis of these compounds.[1,2]
Scheme 1. The bicyclo[3.3.0]octane structural motif in carbacyclin
(1) and the triquinanes hirsutane (2) or silphiperfolene (3).
While many pentalene syntheses rely on cationic, an-
ionic, radical or metal mediated cyclization[3–5] as well as
Diels–Alder reactions,[6] the intermolecular Pauson–Khand
reaction, a [2+2+1]cocyclization of an alkyne, an alkene
and carbon monoxide, provides a convergent approach to
the pentalene skeleton.[7] Particularly the Pauson–Khand
reaction of norbornadiene (7) and functionalized acetylenes
Scheme 2. Retrosynthetic route to highly functionalized bicyclooc-
tane derivatives 4 and 5.
Results and Discussion
The Pauson–Khand cyclization products 6[8] were treated
with diorganocuprates to give the 2,3-trans-disubstituted
cyclopentenones 9[9] without any problems. Compounds 9
could be submitted directly to ozonolysis without protec-
tion[10] of the keto group. The intermediate dialdehydes
[a] Institut für Organische Chemie der Universität Stuttgart,
Pfaffenwaldring 55, 70569 Stuttgart, Germany,
Fax: +49-711-685-4285
E-mail: sabine.laschat@oc.uni-stuttgart.de
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2215

A. Becheanu, A. Baro, S. Laschat, W. Frey
FULL PAPER
[11,12]
were treated with NaBH(OAc)3
which was assumed to
be mild enough for chemoselective reduction of the alde-
hyde groups in the presence of a keto function during
workup. These conditions resulted in clean formation of the
keto diols 10 (Scheme 3, Table 1).
Figure 1. ORTEP view of 2-butyl-4,6-bis(hydroxymethyl)-3-methyl-
hexahydropentalen-1(2H)-one (10a).
Scheme 3. Cuprate addition to compounds 6 followed by oxidative
cleavage of 9 to diols 10.
Table 1. Addition of organocuprates and oxidative cleavage of cy-
clopentenones 9 to diols 10.
Scheme 4. Acetylation of derivatives 10 for differentiation of the
hydroxy groups.
Cuprate addition
Cleavage
9
R1
R2
Yield [%]
10
Yield [%]
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
Pr
Pr
Pr
Bu
Bu
Bu
Me
Bu
Ph
Me
Bu
Ph
94
94
61
98
93
62
96
99
42
85
70
62
87
69
68
a[a]
b
c
d
e
f
g
h
i
j
k
l
57
62
69
22
53
75
30
75
74
50
57
56
34
38
43
Table 2. Chemical acetylation of diols 10 according to Method A
(Scheme 4).
Entry Diol 10 R1
R2
Acetate 4, 5
4/5[a]
1
2
3
4
5
6
7
8
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
Pr
Pr
Pr
Bu
Bu
Bu
C5H11
C5H11
C5H11
C6H13
C6H13
C6H13
Ph
Me
Bu
Ph
Me
Bu
Ph
Me
Bu
Ph
Me
Bu
Ph
Me
Bu
Ph
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
35:65
41:59
46:54
36:64
42:58
48:52
41:59
43:57
46:54
42:58
39:61
45:55
43:57
44:56
51:49
n-C5H11 Me
n-C5H11 Bu
n-C5H11 Ph
n-C6H13 Me
n-C6H13 Bu
n-C6H13 Ph
Ph
Ph
Ph
Me
Bu
Ph
m
n
o
9
10
11
12
13
14
15
[a] Crystallization of 10a from Et2O gave single crystals which are
suitable for X-ray crystallographic analysis (Figure 1).[13] The OR-
TEP plot clearly shows the trans substitution pattern of the butyl
and methyl group at C-2 and C-3.
Ph
Ph
[a] Regioisomeric ratios were determined by capillary GC. Details
for the assignment of 4 and 5 are given in the supporting infor-
mation.
Next, the regio- and diastereoselectivity of the acety-
lation of diols 10 was investigated. In order to establish
proper analytical conditions the chemical acylation[14] was
carried out first (Scheme 4, Table 2).
Thus, the derivatives 10 were acetylated with acetic anhy- tivities than the corresponding derivatives 10 with C-3 sub-
dride in the presence of DMAP in pyridine at room tem- stituents butyl and phenyl (Entries 1, 4, 7, 13).
perature to give the regioisomeric monoacetates 4 and 5 in
The 2-phenyl-substituted monoacetates 4m–o and 5m–o
almost quantitative yields (method A, Scheme 4). Regard- turned out to be sensitive to epimerization at C-2 in the
less of the substituents R1 and R2 in the bicyclo[3.3.0]oc- presence of acids or bases.
tane moiety only regioselectivities up to 35:65 in favour of
For the enzyme-catalyzed acetylation,[15] first various li-
the monoacetate 5 were observed (Table 2). The 3-methyl- pases were screened with diol 10a as model substrate
substituted diols 10a, d, g, m gave slightly better regioselec- (Method B, Scheme 4, Table 3).
2216
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 2215–2225

Highly Functionalized Pentalenes via Intermolecular Pauson–Khand Reaction
FULL PAPER
Table 3. Enzymatic acetylation of 10a with various lipases accord-
ing to method B.
Table 5. Substituent influence on the enzymatic acetylation of diols
10 with chirazyme L1 and vinyl acetate in THF at 40 °C.
Entry
Lipase
Time [h] Conv. [%][a]
4a/5a[a]
Entry Diol R1
R2
Acetate 4, 4/5[a]
Yield of 4
10
5
(%)[b]
1
2
3
4
5
Chirazyme L6
Chirazyme L1
Lipase L-9518
Lipase G
1
1
2
18
18
32 (60)[b]
18 (80)[b]
41 (23)[b]
26 (2)[b]
87:13
91:9
70:30
47:53
37:63
1
2
3
4
5
6
7
8
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
Pr
Pr
Pr
Bu
Bu
Bu
Me
Bu
Ph
Me
Bu
Ph
a
b
c
d
e
f
94:6
35
87
84
43
79
74
36
82
83
Ͼ99:1
Ͼ99:1
92:8
Ͼ99:1
Ͼ99:1
91:9
Ͼ99:1
Ͼ99:1
94:6
Lipase Amano P
31 (63)[b]
[a] Conversion and regioisomeric ratios were determined by capil-
lary GC of the crude products. [b] Diacetate in parenthesis.
C5H11 Me
C5H11 Bu
C5H11 Ph
C6H13 Me
C6H13 Bu
C6H13 Ph
Ph
Ph
Ph
g
h
i
9
10
11
12
13
14
15
j
49
68
k
l
m
n
o
Ͼ99:1
99:1
90:10
99:1
81
The lipases chirazyme L6 and chirazyme L1 gave the best
results leading to good regioselectivities of 87:13 and 91:9,
respectively, in favour of derivative 4a (Entries 1, 2). A sim-
ilar preference for regioisomer 4a was observed for lipase L
albeit with decreased regioselectivity (Entry 3). In contrast,
lipase G and lipase Amano P caused a reversed, but low
regioselectivity (Entries 4, 5). Surprisingly, lipase-mediated
acylations proceeded without any enantioselectivity. Even
chirazyme L1 or L6, which clearly favored one regioisomer,
gave only racemic monoacetate 4a.
Next, the time-dependency of the regioselectivity was in-
vestigated by treating diol 10a with chirazyme L1 and vinyl
acetate in THF at 40 °C (Table 4). THF was found to work
best among the solvents studied (e.g. CH2Cl2, acetone,
MeCN). The highest regioselectivity of 94:6 in favour of
monoacetate 4a was obtained already after 10 min (Entry
1). At prolonged reaction times the regioselectivity grad-
ually decreased.
Me
Bu
Ph
49[c]
32[c]
79[c]
99:1
[a] Regioisomeric ratios were determined by capillary GC of the
crude products. [b] Yields refer to isolated yields. [c] Rapid epi-
merization of 4 was observed under acidic and basic conditions,
respectively.
In order to explain the reversed regioisomeric preference
of chemical and enzymatic acetylation we propose the fol-
lowing mechanistic model. The primary hydroxy groups in
diols 10 differ in their chemical reactivity towards acylation
reagents such as acetic anhydride because the hy-
droxymethyl group at C-6 might be capable of forming an
intramolecular hydrogen bond to the keto group at C-1,
whereas the hydroxymethyl group at C-4 is too far away.
Thus, the reduced nucleophilicity of the hydrogen-bonded
hydroxymethyl group leads to preferred acylation of the hy-
droxy function at C-4 giving monoacetate 5. In contrast,
the active site of the lipase seems to interfere with intramo-
lecular hydrogen bonding presumably due to competing hy-
drogen bonds between the enzyme and the keto group in
diol 10, bringing the hydroxymethyl group at C-6 much
closer to the active site than the corresponding group at C-
4. Thus, the formation of monoacetate 4 is preferred.
Table 4. Enzymatic acetylation of 10a with lipase chirazyme L1 in
dependence on the reaction time.
Entry
Time (min)
Conv. (%)[a][b]
4a/5a[a]
1
2
3
4
5
6
7
10
20
30
40
50
60
70
51
53
52
52
51
51
51
94:6
93:7
93:7
91:9
88:12
87:13
87:13
Conclusion
[a] Conversion and regioisomeric ratios were determined by capil-
lary GC of the crude products. [b] The conversion remains con-
stant, however, the amount of diacetate as by-product increases at
longer reaction times.
The Pauson–Khand reaction of norbornadiene (7) and
substituted acetylenes 8 gives convenient access to meth-
anoindenones 6 which are starting materials for further
functionalization. The synthesis of the target compounds 4
was accomplished by lipase-mediated acetylation with vinyl
Finally, the optimized reaction conditions were applied acetate in THF. Despite the excellent regioselectivity it is
to the lipase-mediated acetylation of diols 10a–o (Table 5). not clear why the lipase does not exert any stereochemical
In contrast to the chemical reaction, the regioselectivities of control. A more efficient approach to the stereoselectivity
the enzymatic acetylations were strongly dependent on the might be achieved directly during the Pauson–Khand reac-
substitution pattern at C-2 and C-3. While the methyl group tion or the cuprate addition. Nevertheless, the sequence of
at C-3 (R2 = Me) led to regioselectivities between 90:10 and Pauson–Khand reaction, subsequent tandem cuprate 1,4-
94:6 in favour of the derivatives 4 (Entries 1, 4, 7, 10, 13), addition/enolate quenching, oxidative cleavage and enzy-
the corresponding 3-butyl- and 3-phenyl-substituted diols matic esterification allows access to highly functionalized
10 resulted in improved regioisomeric ratios up to Ͼ99:1 bicyclo[3.3.0]octane systems which can be further elabo-
(Table 5).
rated.
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2217

A. Becheanu, A. Baro, S. Laschat, W. Frey
FULL PAPER
Ha), 1.20–1.33 (m, 3 H, 1Ј-Ha, 2Ј-Hb, 10-Ha), 1.38–1.43 (m, 1 H,
10-Hb), 1.56–1.60 (m, 1 H, 1Ј-Hb), 2.26 (t, J = 8.4 Hz, 1 H, 6-H),
2.50–2.53 (m, 1 H, 2-H), 2.54 (d, J = 7.6 Hz, 1 H, 4-H), 2.78–2.80
(m, 1 H, 7-H), 2.94–3.00 (m, 1 H, 5-H), 3.07–3.09 (m, 1 H, 1-H),
6.12 (dd, J = 3.1 Hz, J = 5.6 Hz, 1 H, 9-H), 6.17 (dd, J = 2.9 Hz,
J = 5.7 Hz, 1 H, 8-H), 7.23–7.27 (m, 1 H, 4ЈЈ-H), 7.34–7.46 (m, 4
H, 2ЈЈ-H, 3ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR (125 MHz, (CD3)2-
CO): δ = 15.4 (C-3Ј), 21.7 (C-2Ј), 31.6 (C-1Ј), 46.0, 46.1 (C-1, C-
10), 48.1 (C-7), 51.8 (C-6), 54.2 (C-2), 55.4 (C-4), 61.6 (C-5), 128.3
(C-4ЈЈ), 129.5, 130.5 (C-2ЈЈ, C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 139.2, 139.9 (C-8,
Experimental Section
General: The following compounds were prepared according to lit-
erature procedures: 6b–e,[8] 9d–f, h, k, m–o.[9] Melting points were
measured with differential scanning calorimetry and are uncor-
rected. Column chromatography was carried out using Merck SiO2
60 (grain size 0.040–0.063 mm) with hexanes (PE, b.p. 40–60 °C),
pentane and ethyl acetate (EtOAc) as eluents. 1H NMR spectra
were recorded with a Bruker ARX 500 (500 MHz), a Bruker ARX
300 (300 MHz) or a Bruker AC 250 (250 MHz). 13C NMR spectra
were recorded with a Bruker ARX 500 (125 MHz), a Bruker ARX
300 (75 MHz) or a Bruker AC 250 (63 MHz). Multiplicities were
determined with DEPT experiments. GC was carried out with a
Hewlett Packard HP 6890 using an Agilent Technologies HP-5 TA
column (30 m) and hydrogen as the carrier gas. Lipases chirazyme
L1 and L6 were purchased from Boehringer, lipase P and G from
Amano and lipase -9518 from Sigma.
C-9), 146.9 (C-1ЈЈ), 217.2 (C-3) ppm. FT-IR (ATR): ν = 2957 cm–1
˜
(s), 2930 (s), 2871 (m), 1728 (vs), 1493 (m), 1453 (s), 1324 (m), 1284
(m), 1063 (m), 756 (s), 698 (vs) cm–1. GC-MS (EI): m/z (%) = 266.4
(2) [M+], 201.2 (65), 158.2 (22), 128.1 (9), 115.1 (12), 91.1 (16),
66.1 (100). HRMS (CI, CH4): calcd. for C19H22O 266.1671, found
266.1668 [M+].
1
9g: Yield: 324 mg, 96%. Rf = 0.51. H NMR (300 MHz, CDCl3):
General Procedure for the Cuprate Addition to 2,3-Disubstituted
Methanoindenones 9: A suspension of copper iodide (104 mg,
0.54 mmol) in Et2O (5 mL) under N2 was stirred for 10 min at 0 °C
or –20 °C (for Bu2CuLi). Then the organolithium compound
(1.08 mmol) was added dropwise and the reaction mixture stirred
for a further 10 min at 0 °C or –20 °C. The respective compound 6
(0.45 mmol) was added dropwise and after complete conversion
(0.5–2 h, TLC control), the reaction mixture was hydrolyzed with
a satd. solution of NH4Cl (5 mL). The aqueous layer was extracted
with Et2O (5 × 10 mL), and the combined organic layers were dried
(K2CO3) and concentrated. The crude products 9 were purified by
chromatography on SiO2 with pentane/Et2O, 12:1.
δ = 0.88 (t, J = 6.8 Hz, 3 H, 5Ј-H), 1.07 (d, J = 9.2 Hz, 1 H, 10-
Ha), 1.23 [d, J = 6.5 Hz, 3 H, (C-5)CH3], 1.31–1.49 (m, 9 H, 1Ј-
Ha, 2Ј-H, 3Ј-H, 4Ј-H, 5-H, 10-Hb), 1.53–1.66 (m, 1 H, 1Ј-Hb), 1.79–
1.86 (m, 1 H, 6-H), 2.14 (dddd, J = 2.0 Hz, J = 4.4 Hz, J = 6.2 Hz,
J = 12.5 Hz, 1 H, 4-H), 2.30 (d, J = 9.2 Hz, 1 H, 2-H), 2.72–2.76
(m, 1 H, 7-H), 3.10–3.14 (m, 1 H, 1-H), 6.13 (dd, J = 2.9 Hz, J =
5.7 Hz, 1 H, 9-H), 6.17 (dd, J = 2.9 Hz, J = 5.7 Hz, 1 H, 8-H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 14.0 (C-5Ј), 21.0 [(C-5)
CH3], 22.4 (C-4Ј), 26.6, 27.2 (C-1Ј, C-2Ј), 32.1 (C-3Ј), 40.0 (C-5),
44.4 (C-1), 44.8 (C-10), 46.6 (C-7), 48.6 (C-6), 54.2 (C-2), 60.6 (C-
4), 137.3, 138.1 (C-8, C-9), 218.4 (C-3) ppm. FT-IR (ATR): ν =
˜
2954 cm–1 (s), 2926 (s), 2870 (m), 2858 (m), 1731 (vs), 1459 (m),
1324 (m), 1217 (m), 707 (s) cm–1. MS (EI): m/z (%) = 232.1 (6)
[M+], 167.1 (100), 96.0 (19), 66.0 (74), 41.0 (10). HRMS (EI): calcd.
for C16H24O 232.1827, found 232.1827 [M+].
1
9a: Yield: 1.92 g, 94%. Rf = 0.46. H NMR (500 MHz, CDCl3): δ
= 0.91 (t, J = 7.2 Hz, 3 H, 3Ј-H), 1.07 (d, J = 9.1 Hz, 1 H, 10-Ha),
1.23 [d, J = 6.6 Hz, 3 H, (C-5)CH3], 1.25–1.48 (m, 5 H, 1Ј-Ha, 2Ј-
H, 5-H, 10-Hb), 1.55–1.63 (m, 1 H, 1Ј-Hb), 1.80–1.85 (m, 1 H, 6-
H), 2.12–2.18 (m, 1 H, 4-H), 2.28–2.32 (m, 1 H, 2-H), 2.73–2.75
(m, 1 H, 7-H), 3.10–3.13 (m, 1 H, 1-H), 6.13 (dd, J = 3.0 Hz, J =
5.7 Hz, 1 H, 9-H), 6.17 (dd, J = 3.0 Hz, J = 5.7 Hz, 1 H, 8-H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 14.3 (C-3Ј), 20.2 (C-2Ј),
21.0 [(C-5) CH3], 29.7 (C-1Ј), 40.2 (C-5), 44.5 (C-1), 44.8 (C-10),
46.7 (C-7), 48.8 (C-6), 54.3 (C-2), 60.6 (C-4), 137.4, 138.2 (C-8, C-
9i: Yield: 161 mg, 42%. Rf = 0.42. 1H NMR (500 MHz, (CD3)2-
CO): δ = 0.76 (t, J = 7.0 Hz, 3 H, 5Ј-H), 1.12–1.19 (m, 5 H, 2Ј-Ha,
3Ј-H, 4Ј-H), 1.22–1.32 (m, 3 H, 1Ј-Ha, 2Ј-Hb, 10-Ha), 1.38–1.42 (m,
1 H, 10-Hb), 1.51–1.61 (m, 1 H, 1Ј-Hb), 2.27 (t, J = 8.3 Hz, 1 H,
6-H), 2.50–2.56 (m, 2 H, 2-H, 4-H), 2.77–2.80 (m, 1 H, 7-H), 2.93–
2.99 (m, 1 H, 5-H), 3.07–3.10 (m, 1 H, 1-H), 6.12 (dd, J = 3.0 Hz,
J = 5.6 Hz, 1 H, 9-H), 6.17 (dd, J = 2.9 Hz, J = 5.6 Hz, 1 H, 8-
H), 7.23–7.28 (m, 1 H, 4ЈЈ-H), 7.34–7.46 (m, 4 H, 2ЈЈ-H, 3ЈЈ-H, 5ЈЈ-
H, 6ЈЈ-H) ppm. 13C NMR (125 MHz, (CD3)2CO): δ = 15.1 (C-5Ј),
23.9 (C-4Ј), 28.1 (C-2Ј), 29.1 (C-1Ј), 33.5 (C-3Ј), 46.0 (C-1), 46.1
(C-10), 48.1 (C-7), 51.8 (C-6), 54.2 (C-2), 55.4 (C-4), 61.8 (C-5),
128.3 (C-4ЈЈ), 129.6, 130.4 (C-2ЈЈ, C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 139.2, 139.9
9), 218.4 (C-3) ppm. FT-IR (ATR): ν = 2956 cm–1 (s), 2928 (s),
˜
2871 (m), 1730 (vs), 1458 (m), 1352 (m), 1216 (m), 707 (s) cm–1.
GC-MS (EI): m/z (%) = 204.1 (12) [M+], 139.1 (100), 96.0 (12), 66.0
(65). HRMS (EI): calcd. for C14H20O 204.1514, found 204.1514
[M+].
1
9b: Yield: 602 mg, 94%. Rf = 0.54. H NMR (300 MHz, CDCl3):
(C-8, C-9), 146.9 (C-1ЈЈ), 217.2 (C-3) ppm. FT-IR (ATR): ν =
˜
δ = 0.91 (t, J = 7.1 Hz, 3 H, 4ЈЈ-H), 0.95 (t, J = 7.1 Hz, 3 H, 3Ј-
H), 1.07 (d, J = 9.1 Hz, 1 H, 10-Ha), 1.19–1.61 (m, 11 H, 1Ј-Ha,
1ЈЈ-H, 2Ј-H, 2ЈЈ-H, 3ЈЈ-H, 5-H, 10-Hb), 1.66–1.74 (m, 1 H, 1Ј-Hb),
1.89 (dd, J = 5.4 Hz, J = 8.9 Hz, 1 H, 6-H), 2.17–2.22 (m, 1 H, 4-
H), 2.28–2.32 (m, 1 H, 2-H), 2.69–2.71 (m, 1 H, 7-H), 3.10–3.13
(m, 1 H, 1-H), 6.13 (dd, J = 3.0 Hz, J = 5.7 Hz, 1 H, 9-H), 6.19
(dd, J = 3.0 Hz, J = 5.7 Hz, 1 H, 8-H) ppm. 13C NMR (75 MHz,
CDCl3): δ = 14.0 (C-4ЈЈ), 14.4 (C-3Ј), 20.3 (C-3ЈЈ), 29.6, 30.1, 36.4
(C-1Ј, C-1ЈЈ, C-2Ј, C-2ЈЈ), 44.7 (C-1), 44.8 (C-5, C-10), 47.0 (C-6),
48.2 (C-7), 54.4 (C-2), 59.2 (C-4), 137.4, 138.3 (C-8, C-9), 218.9 (C-
2955 cm–1 (s), 2928 (s), 2871 (m), 2856 (s), 1730 (vs), 1493 (m),
1452 (s), 1324 (m), 1284 (m), 1271 (m), 1204 (m), 1072 (m), 754
(s), 698 (vs) cm–1. GC-MS (EI): m/z (%) = 294.4 (1) [M+], 229.3
(69), 158.1 (31), 128.1 (10), 115.0 (14), 91.0 (18), 66.0 (100). HRMS
(CI, CH4): calcd. for C21H26O 294.1984, found 294.1984 [M+].
1
9j: Yield: 309 mg, 85%. Rf = 0.51. H NMR (300 MHz, CDCl3): δ
= 0.87 (t, J = 6.7 Hz, 3 H, 6Ј-H), 1.07 (d, J = 9.2 Hz, 1 H, 10-Ha),
1.23 [d, J = 6.5 Hz, 3 H, (C-5)CH3], 1.25–1.49 (m, 11 H, 1Ј-Ha, 2Ј-
H, 3Ј-H, 4Ј-H, 5-H, 5Ј-H, 10-Hb), 1.51–1.62 (m, 1 H, 1Ј-Hb), 1.79–
1.86 (m, 1 H, 6-H), 2.10–2.18 (m, 1 H, 4-H), 2.27–2.33 (m, 1 H, 2-
H), 2.72–2.76 (m, 1 H, 7-H), 3.10–3.14 (m, 1 H, 1-H), 6.13 (dd, J
= 2.9 Hz, J = 5.7 Hz, 1 H, 9-H), 6.17 (dd, J = 2.9 Hz, J = 5.7 Hz,
1 H, 8-H) ppm. 13C NMR (75 MHz, CDCl3): δ = 14.0 (C-6Ј), 21.0
[(C-5) CH3], 22.5 (C-5Ј), 26.9, 27.3 (C-1Ј, C-2Ј), 29.6 (C-3Ј), 31.6
(C-4Ј), 40.0 (C-5), 44.4 (C-1), 44.8 (C-10), 46.6 (C-7), 48.7 (C-6),
3) ppm. FT-IR (ATR): ν = 2957 cm–1 (s), 2925 (s), 2871 (s), 2859
˜
(s), 1729 (vs), 1458 (s), 1378 (m), 1325 (m), 706 (vs) cm–1. GC-MS
(EI): m/z (%) = 246.2 (6) [M+], 181.1 (100), 125.1 (4), 95.0 (7), 66.0
(41). HRMS (EI): calcd. for C17H26O 246.1984, found 246.1984
[M+]. C17H26O (246.4): calcd. C 82.87, H 10.64; found C 82.86, H
10.76.
9c: Yield: 866 mg, 61%. Rf = 0.37. 1H NMR (500 MHz, (CD3)2- 54.2 (C-2), 60.7 (C-4), 137.4, 138.2 (C-8, C-9), 218.4 (C-3) ppm.
CO): δ = 0.72 (t, J = 7.2 Hz, 3 H, 3Ј-H), 1.05–1.15 (m, 1 H, 2Ј- FT-IR (ATR): ν = 2954 cm–1 (s), 2925 (s), 2870 (m), 2856 (m), 1732
˜
2218
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 2215–2225

Highly Functionalized Pentalenes via Intermolecular Pauson–Khand Reaction
FULL PAPER
(vs), 1458 (m), 1324 (m), 1217 (m), 707 (s) cm–1. GC-MS (EI): 30.9 (C-3ЈЈ), 33.6 (C-1ЈЈ), 34.1 (C-5), 44.0 (C-6), 46.0 (C-3), 48.1,
m/z (%) = 246.2 (12) [M+], 181.1 (100), 96.0 (12), 66.1 (40), 41.0 (4).
48.3 (C-3a, C-4), 55.7 (C-2), 57.5 (C-6a), 66.2, 66.5 [(C-4) CH2OH,
HRMS (EI): calcd. for C17H26O 246.1984, found 246.1988 [M+].
(C-6) CH OH] ppm. FT-IR (ATR): ν = 3362 cm–1 (s), 2955 (s),
˜
2
2924 (s), 2870 (s), 1718 (vs), 1464 (m), 1378 (m), 1052 (s), 903 (s),
727 (vs), 649 (s) cm–1. GC-MS (EI): m/z (%) = 281.1 (1) [(M – H)
+], 264.4 (1), 240.4 (3), 183.2 (100), 147.2 (6), 119.2 (5), 91.1 (4),
79.1 (8), 67.1 (8), 55.1 (14). HRMS (CI, CH4): calcd. for C17H31O3
283.2273, found 283.2273 [M + H]+.
9l: Yield: 1.13 g, 62%. Rf = 0.31. 1H NMR (500 MHz, (CD3)2CO):
δ = 0.80 (t, J = 7.2 Hz, 3 H, 6Ј-H), 1.05–1.31 (m, 10 H, 1Ј-Ha, 2Ј-
H, 3Ј-H, 4Ј-H, 5Ј-H, 10-Ha), 1.39–1.43 (m, 1 H, 10-Hb), 1.51–1.61
(m, 1 H, 1Ј-Hb), 2.27 (t, J = 8.4 Hz, 1 H, 6-H), 2.51–2.56 (m, 2 H,
2-H, 4-H), 2.78–2.80 (m, 1 H, 7-H), 2.93–3.00 (m, 1 H, 5-H), 3.07–
3.10 (m, 1 H, 1-H), 6.12 (dd, J = 3.0 Hz, J = 5.6 Hz, 1 H, 9-H),
6.17 (dd, J = 2.9 Hz, J = 5.7 Hz, 1 H, 8-H), 7.23–7.28 (m, 1 H, 4ЈЈ-
H), 7.34–7.46 (m, 4 H, 2ЈЈ-H, 3ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR
(125 MHz, (CD3)2CO): δ = 15.2 (C-6Ј), 24.1 (C-5Ј), 28.4, 29.2, 31.0,
33.2 (C-1Ј, C-2Ј, C-3Ј, C-4Ј), 46.0 (C-1), 46.1 (C-10), 48.1 (C-7),
51.8 (C-6), 54.2 (C-2), 55.4 (C-4), 61.8 (C-5), 128.3 (C-4ЈЈ), 129.6,
130.4 (C-2ЈЈ, C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 139.2, 139.9 (C-8, C-9), 147.0 (C-
1
10c: Yield: 683 mg, 69%. Rf = 0.31. H NMR (500 MHz, (CD3)2-
CO): δ = 0.73 (t, J = 7.2 Hz, 3 H, 3Ј-H), 1.05–1.12 (m, 1 H, 2Ј-
Ha), 1.24–1.36 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.42–1.55 (m, 2 H, 1Ј-Hb, 5-
Ha), 2.08–2.24 (m, 3 H, 4-H, 5-Hb, 6-H), 2.60–2.69 (m, 2 H, 2-H,
3a-H), 2.74 (dt, J = 1.2 Hz, J = 9.4 Hz, 1 H, 6a-H), 2.82 (dd, J =
9.6 Hz, J = 12.3 Hz, 1 H, 3-H), 3.21 [dd, J = 6.8 Hz, J = 10.4 Hz,
1 H, (C-4)CHaOH], 3.30 [dd, J = 5.2 Hz, J = 10.4 Hz, 1 H, (C-4)
CHbOH], 3.55 [dd, J = 5.9 Hz, J = 10.3 Hz, 1 H, (C-6)CHaOH],
3.69 [dd, J = 5.4 Hz, J = 10.4 Hz, 1 H, (C-6)CHbOH], 7.23–7.26
(m, 1 H, 4ЈЈ-H), 7.32–7.36 (m, 2 H, 3ЈЈ-H, 5ЈЈ-H), 7.39–7.42 (m, 2
H, 2ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR (125 MHz, (CD3)2CO): δ = 15.4
(C-3Ј), 21.6 (C-2Ј), 31.9 (C-1Ј), 36.2 (C-5), 46.4 (C-6), 49.3 (C-4),
53.2 (C-3a), 56.2 (C-3), 56.9 (C-6a), 59.5 (C-2), 66.8, 67.2 [(C-4)
CH2OH, (C-6) CH2OH], 128.4 (C-4ЈЈ), 129.6 (C-2ЈЈ, C-6ЈЈ), 130.4
1ЈЈ), 217.2 (C-3) ppm. FT-IR (ATR): ν = 2955 cm–1 (s), 2926 (s),
˜
2870 (m), 2855 (s), 1731 (vs), 1493 (m), 1452 (s), 1324 (m), 1284
(m), 1207 (m), 1067 (m), 754 (s), 698 (vs) cm–1. GC-MS (EI):
m/z (%) = 306.9 (1) [(M – H)+], 243.3 (70), 158.1 (26), 128.1 (8),
115.1 (12), 91.1 (17), 66.0 (100). HRMS (CI, CH4): calcd. for
C22H28O 308.2140, found 308.2137 [M+].
General Procedure for the Preparation of Bis(hydroxymethyl)hexa-
hydropentalen-1(2H)-ones 10: A stream of O3 was passed through
a solution of 9 (2.42 mmol) in CHCl3 (30 mL) at –78 °C until a
light blue color was visible. Then N2 was passed through for
10 min, sodium triacetoxyborohydride (5.31 g, 24.3 mmol) was
added portionwise and the reaction mixture warmed to room tem-
perature. After stirring for 0.5 h, the reaction mixture was heated
at reflux for 3 h. Then it was hydrolyzed with a satd. solution of
NH4Cl (30 mL), and the aqueous layer was extracted with CHCl3
and EtOAc (3 × 30 mL each). The combined organic layers were
dried (K2CO3) and concentrated. The residue was chromato-
graphed on SiO2 with PE/EtOAc, 1:3.
(C-3ЈЈ, C-5ЈЈ), 145.0 (C-1ЈЈ) ppm. FT-IR (ATR): ν = 3359 cm–1 (s),
˜
2955 (s), 2915 (s), 2870 (s), 1720 (vs), 1495 (m), 1454 (s), 1374 (s),
1305 (m), 1241 (s), 1158 (m), 1082 (s), 1046 (vs), 917 (m), 760 (s),
736 (m), 699 (vs) cm–1. GC-MS (EI): m/z (%) = 302.3 (10) [M+],
284.3 (11), 273.3 (15), 260.2 (86), 242.2 (31), 201.1 (20), 169.1 (11),
146.1 (20), 131.1 (16), 117.0 (92), 104.1 (41), 91.0 (100), 79.1 (26),
67.1 (16), 55.0 (31). HRMS (CI, CH4): calcd. for C19H27O3
303.1960, found 303.1951 [M + H]+.
1
10d: Yield: 53 mg, 22%. Rf = 0.22. H NMR (500 MHz, (CD3)2-
CO): δ = 0.91 (t, J = 7.1 Hz, 3 H, 4Ј-H), 1.19 (d, J = 6.5 Hz, 3 H,
CH3), 1.22–1.52 (m, 6 H, 1Ј-Ha, 2Ј-Ha, 2Ј-Hb, 3Ј-H, 5-Ha), 1.54–
1.62 (m, 1 H, 1Ј-Hb), 1.64–1.73 (m, 1 H, 3-H), 1.94–1.98 (m, 1 H,
2-H), 1.99–2.16 (m, 4 H, 3a-H, 4-H, 5-Hb, 6-H), 2.55 (t, J = 8.7 Hz,
1 H, 6a-H), 3.44–3.74 [m, 4 H, (C-4)CH2OH, (C-6)CH2OH] ppm.
13C NMR (125 MHz, (CD3)2CO): δ = 15.2 (C-4Ј), 19.8 (CH3), 24.6
(C-3Ј), 28.9 (C-1Ј), 30.8 (C-2Ј), 36.2 (C-5), 44.1 (C-3), 46.2 (C-6),
49.8 (C-3a), 53.0 (C-4), 57.0 (C-6a), 59.6 (C-2), 66.8, 67.8 [(C-4)
10a: Yield: 2.81 g, 57%. Rf = 0.19. M.p. 87 °C. 1H NMR
(500 MHz, CDCl3): δ = 0.91 (t, J = 7.2 Hz, 3 H, 3Ј-H), 1.18 (d, J
= 6.5 Hz, 3 H, CH3), 1.20–1.37 (m, 2 H, 2Ј-Ha, 5-Ha), 1.38–1.52
(m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.52–1.59 (m, 1 H, 1Ј-Hb), 1.60–1.69 (m, 1
H, 3-H), 1.95–2.01 (m, 1 H, 2-H), 2.03–2.19 (m, 4 H, 3a-H, 4-H,
5-Hb, 6-H), 2.62 (t, J = 9.1 Hz, 1 H, 6a-H), 3.55 [dd, J = 8.0 Hz,
J = 10.7 Hz, 1 H, (C-6)CHaOH], 3.60 [dd, J = 4.0 Hz, J = 5.6 Hz,
2 H, (C-4)CH2OH], 3.73 [dd, J = 4.1 Hz, J = 10.6 Hz, 1 H, (C-6)
CHbOH] ppm. 13C NMR (125 MHz, CDCl3): δ = 14.3 (C-3Ј), 18.3
(CH3), 19.9 (C-2Ј), 29.2 (C-1Ј), 34.3 (C-5), 42.8 (C-3), 43.9 (C-6),
47.4 (C-3a), 51.1 (C-4), 57.7, 58.3 (C-2, C-6a), 66.4, 66.7 [(C-4)
CH OH, (C-6) CH OH] ppm. FT-IR (ATR): ν = 3317 cm–1 (s),
˜
2
2
2956 (s), 2930 (s), 2898 (s), 2857 (s), 1722 (vs), 1481 (m), 1448 (m),
1403 (m), 1377 (m), 1338 (m), 1311 (m), 1276 (m), 1227 (m), 1170
(m), 1115 (s), 1081 (s), 1028 (vs), 1003 (s), 988 (s) cm–1. GC-MS
(EI): m/z (%) = 254.5 (2) [M+], 239.3 (6), 198.3 (9), 183.2 (100),
165.2 (6), 147.2 (6), 79.0 (13), 69.1 (11), 55.1 (19). HRMS (CI,
CH4): calcd. for C15H26O3 254.1882, found 254.1879 [M+].
CH OH, (C-6) CH OH], 222.3 (C-1) ppm. FT-IR (ATR): ν =
˜
2
2
3310 cm–1 (s), 2957 (s), 2932 (s), 2898 (s), 2869 (s), 2820 (m), 1722
(vs), 1481 (m), 1449 (m), 1404 (m), 1377 (m), 1338 (m), 1313 (m),
1277 (m), 1225 (m), 1171 (m), 1116 (s), 1082 (s), 1029 (vs), 1003
(s), 989 (s) cm–1. MS (EI): m/z (%) = 240.2 (2) [M+], 222.1 (4), 198.1
(18), 183.1 (100), 165.1 (5), 147.0 (8), 118.0 (22), 91.0 (15), 79.0
(10), 67.0 (7). C14H24O3 (240.3): calcd. C 69.96, H 10.07; found C
70.01, H 10.11.
1
10e: Yield: 165 mg, 53%. Rf = 0.35. H NMR (500 MHz, CDCl3):
δ = 0.90 (t, J = 7.1 Hz, 3 H, 4ЈЈ-H), 0.92 (t, J = 6.8 Hz, 3 H, 4Ј-
H), 1.18–1.36 (m, 9 H, 2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 5-Ha), 1.49–1.62
(m, 4 H, 1Ј-H, 1ЈЈ-H), 1.71–1.78 (m, 1 H, 3-H), 2.02–2.24 (m, 5 H,
2-H, 3a-H, 4-H, 5-Hb, 6-H), 2.63 (t, J = 9.4 Hz, 1 H, 6a-H), 3.55
[dd, J = 8.0 Hz, J = 10.7 Hz, 1 H, (C-6)CHaOH], 3.57 [dd, J =
10b: Yield: 619 mg, 62%. Rf = 0.32. M.p. 51 °C. 1H NMR 6.0 Hz, J = 10.8 Hz, 1 H, (C-4)CHaOH], 3.67 [dd, J = 5.1 Hz, J =
(500 MHz, CDCl3): δ = 0.91 (t, J = 7.1 Hz, 3 H, 4ЈЈ-H), 0.93 (t, J 10.6 Hz, 1 H, (C-4)CHbOH], 3.72 [dd, J = 4.5 Hz, J = 10.7 Hz, 1
= 6.8 Hz, 3 H, 3Ј-H), 1.20–1.44 (m, 7 H, 2Ј-H, 2ЈЈ-H, 3ЈЈ-H, 5-Ha), H, (C-6)CHbOH] ppm. 13C NMR (125 MHz, CDCl3): δ = 13.9,
1.46–1.62 (m, 4 H, 1Ј-H, 1ЈЈ-H), 1.70–1.77 (m, 1 H, 3-H), 2.00– 14.0 (C-4Ј, C-4ЈЈ), 22.9, 23.1 (C-3Ј, C-3ЈЈ), 28.3 (C-1Ј), 28.5, 29.0
2.24 (m, 5 H, 2-H, 3a-H, 4-H, 5-Hb, 6-H), 2.63 (t, J = 8.7 Hz, 1 H,
6a-H), 3.55 [dd, J = 8.1 Hz, J = 10.7 Hz, 1 H, (C-6)CHaOH], 3.57
(C-2Ј, C-2ЈЈ), 33.6 (C-1ЈЈ), 34.1 (C-5), 44.0 (C-6), 45.9 (C-3), 48.1,
48.3 (C-3a, C-4), 55.8 (C-2), 57.5 (C-6a), 66.2, 66.5 [(C-4) CH2OH,
[dd, J = 5.6 Hz, J = 11.1 Hz, 1 H, (C-4)CHaOH], 3.67 [dd, J = (C-6) CH OH] ppm. FT-IR (ATR): ν = 3362 cm–1 (s), 2954 (s),
˜
2
5.2 Hz, J = 10.5 Hz, 1 H, (C-4)CHbOH], 3.71 [dd, J = 4.5 Hz, J =
10.6 Hz, 1 H, (C-6)CHbOH] ppm. 13C NMR (125 MHz, CDCl3): 903 (s), 727 (s), 649 (s) cm–1. GC-MS (EI): m/z (%) = 296.6 (1)
δ = 14.0 (C-4ЈЈ), 14.3 (C-3Ј), 20.1 (C-2Ј), 23.1 (C-2ЈЈ), 28.5 (C-1Ј),
[M+], 239.4 (7), 183.2 (100), 165.3 (7), 147.2 (8), 119.2 (7), 91.1 (5),
2925 (s), 2858 (s), 1719 (vs), 1465 (m), 1378 (m), 1053 (s), 1028 (s),
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2219

A. Becheanu, A. Baro, S. Laschat, W. Frey
79.1 (8), 67.1 (7), 55.1 (15). HRMS (CI, CH4): calcd. for C18H32O3 H, 3a-H), 2.74 (dt, J = 1.1 Hz, J = 9.5 Hz, 1 H, 6a-H), 2.80–2.87
FULL PAPER
296.2351, found 296.2348 [M+].
(m, 1 H, 3-H), 3.18–3.24 [m, 1 H, (C-4)CHaOH], 3.30 [td, J =
5.0 Hz, J = 10.1 Hz, 1 H, (C-4)CHbOH], 3.55 [ddd, J = 6.2 Hz, J
= 7.8 Hz, J = 11.2 Hz, 1 H, (C-6)CHaOH], 3.69 [dd, J = 5.6 Hz, J
= 9.2 Hz, 1 H, (C-6)CHbOH], 7.22–7.26 (m, 1 H, 4ЈЈ-H), 7.32–7.36
(m, 2 H, 3ЈЈ-H, 5ЈЈ-H), 7.39–7.42 (m, 2 H, 2ЈЈ-H, 6ЈЈ-H) ppm. 13C
NMR (125 MHz, (CD3)2CO): δ = 15.1 (C-5Ј), 23.9 (C-4Ј), 28.0 (C-
2Ј), 29.4 (C-1Ј), 33.5 (C-3Ј), 36.2 (C-5), 46.4 (C-6), 49.3 (C-4), 53.2
(C-3a), 56.2 (C-3), 56.9 (C-6a), 59.7 (C-2), 66.8, 67.2 [(C-4)
CH2OH, (C-6) CH2OH], 128.4 (C-4ЈЈ), 129.6 (C-2ЈЈ, C-6ЈЈ), 130.3
1
10f: Yield: 190 mg, 75%. Rf = 0.32. H NMR (500 MHz, (CD3)2-
CO): δ = 0.75 (t, J = 7.2 Hz, 3 H, 4Ј-H), 1.01–1.10 (m, 3 H, 2Ј-Ha,
3Ј-H), 1.23–1.30 (m, 1 H, 2Ј-Hb), 1.36 (tdd, J = 5.0 Hz, J = 10.2 Hz,
J = 13.3 Hz, 1 H, 1Ј-Ha), 1.42–1.51 (m, 2 H, 1Ј-Hb, 5-Ha), 2.08–
2.25 (m, 3 H, 4-H, 5-Hb, 6-H), 2.61–2.68 (m, 2 H, 2-H, 3a-H), 2.74
(dt, J = 1.1 Hz, J = 9.5 Hz, 1 H, 6a-H), 2.80–2.83 (m, 1 H, 3-H),
3.18–3.24 [m, 1 H, (C-4)CHaOH], 3.28–3.32 [m, 1 H, (C-4)
CHbOH], 3.52–3.58 [m, 1 H, (C-6)CHaOH], 3.66–3.72 [m, 1 H, (C-
6)CHbOH], 7.22–7.26 (m, 1 H, 4ЈЈ-H), 7.32–7.37 (m, 2 H, 3ЈЈ-H,
5ЈЈ-H), 7.38–7.42 (m, 2 H, 2ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR (125 MHz,
(CD3)2CO): δ = 15.0 (C-4Ј), 24.4 (C-3Ј), 29.1 (C-1Ј), 30.5 (C-2Ј),
36.2 (C-5), 46.4 (C-6), 49.3 (C-4), 53.1 (C-3a), 56.1 (C-3), 56.9 (C-
6a), 59.6 (C-2), 66.8, 67.2 [(C-4) CH2OH, (C-6) CH2OH], 128.4 (C-
4ЈЈ), 129.6 (C-2ЈЈ, C-6ЈЈ), 130.3 (C-3ЈЈ, C-5ЈЈ), 145.0 (C-1ЈЈ) ppm.
(C-3ЈЈ, C-5ЈЈ), 145.0 (C-1ЈЈ) ppm. FT-IR (ATR): ν = 3371 cm–1 (s),
˜
2925 (s), 2858 (s), 1724 (vs), 1495 (m), 1454 (s), 1374 (m), 1240 (s),
1157 (m), 1079 (s), 1047 (vs), 974 (m), 760 (s), 724 (m), 699 (vs)
cm–1. GC-MS (EI): m/z (%) = 330.3 (59) [M+], 273.2 (20), 260.1
(76), 242.2 (41), 229.2 (32), 201.1 (47), 183.0 (20), 155.0 (15), 130.7
(33), 117.0 (46), 104.0 (87), 91.0 (100), 78.9 (32), 67.0 (39), 55.0
(32). HRMS (EI): calcd. for C21H30O3 330.2195, found 330.2192
[M+].
FT-IR (ATR): ν = 3399 cm–1 (s), 2926 (s), 2871 (s), 1726 (vs), 1495
˜
(m), 1454 (s), 1373 (s), 1240 (s), 1158 (m), 1044 (vs), 923 (m), 760
(s), 728 (m), 700 (vs) cm–1. GC-MS (EI): m/z (%) = 316.3 (50) [M+],
298.3 (6), 273.3 (26), 260.2 (79), 242.3 (34), 201.1 (18), 160.1 (25),
141.2 (13), 131.1 (22), 117.1 (81), 104.1 (81), 91.0 (100), 79.1 (29),
67.1 (28), 55.0 (37). HRMS (EI): calcd. for C20H28O3 316.2038,
found 316.2044 [M+].
10j: Yield: 899 mg, 50%. Rf = 0.27. M.p. 54 °C. 1H NMR
(500 MHz, CDCl3): δ = 0.88 (t, J = 6.8 Hz, 3 H, 6Ј-H), 1.18 (d, J
= 6.4 Hz, 3 H, CH3), 1.20–1.34 (m, 8 H, 2Ј-Ha, 3Ј-H, 4Ј-H, 5Ј-H,
5-Ha), 1.35–1.43 (m, 1 H, 2Ј-Hb), 1.45–1.52 (m, 1 H, 1Ј-Ha), 1.53–
1.60 (m, 1 H, 1Ј-Hb), 1.61–1.70 (m, 1 H, 3-H), 1.95–2.00 (m, 1 H,
2-H), 2.01–2.17 (m, 4 H, 3a-H, 4-H, 5-Hb, 6-H), 2.62 (t, J = 9.0 Hz,
1 H, 6a-H), 3.55 [dd, J = 8.0 Hz, J = 10.6 Hz, 1 H, (C-6)CHaOH],
3.60 [dd, J = 2.6 Hz, J = 5.7 Hz, 2 H, (C-4)CH2OH], 3.73 [dd, J =
4.0 Hz, J = 5.6 Hz, 1 H, (C-6)CHbOH] ppm. 13C NMR (125 MHz,
CDCl3): δ = 14.0 (C-6Ј), 18.3 (CH3), 22.5 (C-5Ј), 26.7 (C-2Ј), 27.0
(C-1Ј), 29.6 (C-3Ј), 31.6 (C-4Ј), 34.4 (C-5), 42.8 (C-3), 43.9 (C-6),
47.5 (C-3a), 51.2 (C-4), 57.8 (C-6a), 58.5 (C-2), 66.5, 66.7 [(C-4)
1
10g: Yield: 108 mg, 30%. Rf = 0.32. H NMR (500 MHz, (CD3)2-
CO): δ = 0.89 (t, J = 6.9 Hz, 3 H, 5Ј-H), 1.19 (d, J = 6.6 Hz, 3 H,
CH3), 1.23–1.38 (m, 7 H, 2Ј-H, 3Ј-H, 4Ј-H, 5-Ha), 1.41–1.50 (m, 1
H, 1Ј-Ha), 1.51–1.61 (m, 1 H, 1Ј-Hb), 1.62–1.73 (m, 1 H, 3-H),
1.92–1.98 (m, 1 H, 2-H), 1.99–2.17 (m, 4 H, 3a-H, 4-H, 5-Hb, 6-
H), 2.54 (t, J = 9.2 Hz, 1 H, 6a-H), 3.47–3.74 [m, 4 H, (C-4)
CH2OH, (C-6)CH2OH] ppm. 13C NMR (125 MHz, (CD3)2CO): δ
= 15.3 (C-5Ј), 19.8 (CH3), 24.1 (C-4Ј), 28.2 (C-2Ј), 29.2 (C-1Ј), 33.9
(C-3Ј), 36.2 (C-5), 44.1 (C-3), 46.2 (C-6), 49.8 (C-3a), 53.0 (C-4),
57.0 (C-6a), 59.6 (C-2), 66.8, 67.8 [(C-4) CH2OH, (C-6) CH2OH]
CH OH, (C-6) CH OH] ppm. FT-IR (ATR): ν = 3366 cm–1 (s),
˜
2
2
2952 (s), 2924 (s), 2856 (s), 1720 (vs), 1458 (m), 1378 (m), 1054 (s),
1016 (s), 903 (vs), 724 (vs) cm–1. GC-MS (EI): m/z (%) = 282.4 (4)
[M+], 267.4 (12), 198.3 (6), 183.2 (100), 147.2 (6), 119.2 (5), 91.1
(6), 79.1 (12), 67.1 (10), 55.1 (18). HRMS (CI, CH4): calcd. for
C17H31O3 283.2273, found 283.2273 [M + H]+.
ppm. FT-IR (ATR): ν = 3317 cm–1 (s), 2954 (s), 2926 (s), 2898 (s),
˜
2853 (s), 1722 (vs), 1480 (m), 1448 (m), 1406 (m), 1377 (m), 1337
(m), 1312 (m), 1274 (m), 1224 (m), 1170 (m), 1116 (s), 1082 (s),
1027 (vs), 1002 (s), 989 (s) cm–1. GC-MS (EI): m/z (%) = 268.4 (3)
[M+], 253.4 (12), 198.2 (9), 183.2 (100), 147.2 (6), 91.1 (6), 79.1
(11), 67.0 (11), 55.1 (18). HRMS (CI, CH4): calcd. for C16H28O3
268.2038, found 268.2032 [M+].
1
10k: Yield: 921 mg, 57%. Rf = 0.28. H NMR (500 MHz, (CD3)2-
CO): δ = 0.88 (t, J = 6.8 Hz, 3 H, 6Ј-H), 0.89 (t, J = 7.2 Hz, 3 H,
4ЈЈ-H), 1.20–1.44 (m, 13 H, 2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 4Ј-H, 5Ј-H,
5-Ha), 1.46–1.60 (m, 4 H, 1Ј-H, 1ЈЈ-H), 1.70–1.77 (m, 1 H, 3-H),
1.90–2.22 (m, 5 H, 2-H, 3a-H, 4-H, 5-Hb, 6-H), 2.53 (t, J = 8.9 Hz,
1 H, 6a-H), 3.43–3.58 [m, 4 H, (C-4)CH2OH, (C-6)CH2OH] ppm.
13C NMR (125 MHz, (CD3)2CO): δ = 15.3 (C-6Ј, C-4ЈЈ), 24.2, 24.8
(C-5Ј, C-3ЈЈ), 28.7 (C-2Ј), 31.0, 31.2, 31.3 (C-1Ј, C-2ЈЈ, C-3Ј), 33.4
(C-4Ј), 35.9, 36.0 (C-1ЈЈ, C-5), 45.9 (C-6), 47.0 (C-3), 50.2, 50.4 (C-
3a, C-4), 57.0, 57.0 (C-2, C-6a), 67.0, 67.1 [(C-4) CH2OH, (C-6)
CH OH] ppm. FT-IR (ATR): ν = 3375 cm–1 (s), 2954 (s), 2922 (vs),
1
10h: Yield: 370 mg, 75%. Rf = 0.21. H NMR (500 MHz, CDCl3):
δ = 0.88 (t, J = 7.0 Hz, 3 H, 5Ј-H), 0.92 (t, J = 7.0 Hz, 3 H, 4ЈЈ-
H), 1.20–1.40 (m, 13 H, 2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 4Ј-H, 4ЈЈ-H, 5-
Ha), 1.48–1.62 (m, 4 H, 1Ј-H, 1ЈЈ-H), 1.70–1.77 (m, 1 H, 3-H),
2.02–2.24 (m, 5 H, 2-H, 3a-H, 4-H, 5-Hb, 6-H), 2.63 (t, J = 8.7 Hz,
1 H, 6a-H), 3.55 [dd, J = 7.9 Hz, J = 10.6 Hz, 1 H, (C-6)CHaOH],
3.58 [dd, J = 6.1 Hz, J = 10.5 Hz, 1 H, (C-4)CHaOH], 3.67 [dd, J
= 5.2 Hz, J = 10.5 Hz, 1 H, (C-4)CHbOH], 3.72 [dd, J = 4.6 Hz, J
= 10.6 Hz, 1 H, (C-6)CHbOH] ppm. 13C NMR (125 MHz, CDCl3):
δ = 14.0 (C-5Ј, C-4ЈЈ), 22.4 (C-4Ј), 23.1 (C-3ЈЈ), 26.5 (C-2Ј), 28.5,
28.6 (C-1Ј, C-2ЈЈ), 32.0 (C-3Ј), 33.5 (C-1ЈЈ), 34.2 (C-5), 44.0 (C-6),
46.0 (C-3), 48.1, 48.3 (C-3a, C-4), 55.9 (C-2), 57.5 (C-6a), 66.2, 66.5
˜
2
2856 (s), 1720 (vs), 1458 (m), 1377 (m), 1050 (s), 1026 (s), 724 (m),
620 (m) cm–1. GC-MS (EI): m/z (%) = 324.2 (1) [M+], 267.1 (16),
183.0 (100), 165.0 (5), 147.0 (7), 119.0 (5), 91.1 (5), 78.9 (7), 66.9
(8), 55.1 (17). HRMS (CI, CH4): calcd. for C20H37O3 325.2742,
found 325.2742 [M + H]+.
[(C-4) CH OH, (C-6) CH OH] ppm. FT-IR (ATR): ν = 3392 cm–1
˜
2
2
1
10l: Yield: 606 mg, 56%. Rf = 0.35. H NMR (500 MHz, (CD3)2-
(s), 2954 (s), 2925 (vs), 2858 (s), 1721 (vs), 1465 (m), 1378 (m), 1053
(s), 1028 (s), 903 (s), 726 (s), 650 (s) cm–1. GC-MS (EI): m/z (%) =
311.6 (4) [M + H]+, 253.4 (12), 183.3 (100), 147.3 (6), 119.2 (5),
91.1 (5), 79.1 (8), 67.1 (8), 55.1 (14). HRMS (CI, CH4): calcd. for
C19H34O3 310.2508, found 310.2564 [M+].
CO): δ = 0.81 (t, J = 7.2 Hz, 3 H, 6Ј-H), 1.05–1.17 (m, 7 H, 2Ј-Ha,
3Ј-H, 4Ј-H, 5Ј-H), 1.24–1.39 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.41–1.57 (m,
2 H, 1Ј-Hb, 5-Ha), 2.08–2.26 (m, 3 H, 4-H, 5-Hb, 6-H), 2.61–2.69
(m, 2 H, 2-H, 3a-H), 2.74 (dt, J = 1.4 Hz, J = 9.5 Hz, 1 H, 6a-H),
2.79–2.90 (m, 1 H, 3-H), 3.21 [dd, J = 6.8 Hz, J = 10.1 Hz, 1 H,
(C-4)CHaOH], 3.30 [dd, J = 5.0 Hz, J = 10.3 Hz, 1 H, (C-4)
CHbOH], 3.55 [dd, J = 6.0 Hz, J = 9.5 Hz, 1 H, (C-6)CHaOH],
1
10i: Yield: 143 mg, 74%. Rf = 0.31. H NMR (500 MHz, (CD3)2-
CO): δ = 0.77 (t, J = 7.1 Hz, 3 H, 5Ј-H), 1.05–1.19 (m, 4 H, 3Ј-H,
4Ј-H), 1.24–1.39 (m, 3 H, 2Ј-H, 1Ј-Ha), 1.42–1.52 (m, 2 H, 1Ј-Hb, 3.69 [dd, J = 5.5 Hz, J = 10.5 Hz, 1 H, (C-6)CHbOH], 7.21–7.26
5-Ha), 2.08–2.25 (m, 3 H, 4-H, 5-Hb, 6-H), 2.61–2.69 (m, 2 H, 2- (m, 1 H, 4ЈЈ-H), 7.32–7.37 (m, 2 H, 3ЈЈ-H, 5ЈЈ-H), 7.39–7.42 (m, 2
2220
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 2215–2225

Highly Functionalized Pentalenes via Intermolecular Pauson–Khand Reaction
FULL PAPER
H, 2ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR (125 MHz, (CD3)2CO): δ = 15.2
(C-6Ј), 24.1 (C-5Ј), 28.3 (C-2Ј), 29.5 (C-1Ј), 31.0 (C-3Ј), 33.2 (C-
(s), 3028 (m), 2918 (s), 2871 (s), 1724 (vs), 1601 (m), 1495 (s), 1451
(s), 1374 (m), 1278 (m), 1134 (m), 1074 (s), 1045 (vs), 1025 (s), 968
4Ј), 36.2 (C-5), 46.4 (C-6), 49.3 (C-4), 53.2 (C-3a), 56.2 (C-3), 56.9 (m), 929 (m), 753 (s), 696 (vs) cm–1. GC-MS (EI): m/z (%) = 336.1
(C-6a), 59.7 (C-2), 66.8, 67.2 [(C-4) CH2OH, (C-6) CH2OH], 128.4
(C-4ЈЈ), 129.6 (C-2ЈЈ, C-6ЈЈ), 130.3 (C-3ЈЈ, C-5ЈЈ), 145.0 (C-1ЈЈ) ppm.
(80) [M+], 206.3 (12), 179.0 (48), 165.0 (25), 118.0 (100), 105.0 (16),
91.0 (52), 79.0 (14), 67.0 (14). HRMS (EI): calcd. for C22H24O3
336.1725, found 336.1726 [M+].
FT-IR (ATR): ν = 3379 cm–1 (s), 2952 (s), 2924 (s), 2856 (s), 1724
˜
(vs), 1495 (m), 1454 (s), 1374 (s), 1241 (s), 1157 (m), 1077 (s), 1046
(vs), 760 (s), 730 (m), 699 (vs) cm–1. GC-MS (EI): m/z (%) = 344.3
(33) [M+], 273.2 (29), 260.2 (91), 242.1 (30), 229.2 (7), 211.1 (17),
201.1 (21), 183.1 (20), 158.0 (23), 128.9 (19), 117.0 (53), 104.0 (77),
91.0 (100), 79.0 (28), 67.0 (21), 55.0 (40). HRMS (EI): calcd. for
C22H32O3 344.2351, found 344.2357 [M+].
General Procedure for the Enzymatic Esterification to 4,5-Disubsti-
tuted [3-(Hydroxymethyl)-6-oxooctahydropentalen-1-yl]methyl Ace-
tates 4 and 5,6-Disubstituted [3-(Hydroxymethyl)-4-oxooctahydro-
pentalen-1-yl]methyl Acetates 5: A mixture of the appropriate 10
(1.13 mmol), molecular sieves (62 pellets, 4 Å), vinyl acetate (94 µL,
87 mg, 1.01 mmol) and lipase (34 mg) in freshly distilled absolute
THF (12 mL) was heated at 40 °C for 5–30 min (GC control). The
reaction mixture was filtered through cellulose, the filtrate concen-
trated and chromatographed on SiO2 with PE/EtOAc, 1:1. GC:
HP-5 TA column, gradient 16 °C min–1 from 80 °C to 300 °C, then
300 °C for 17 min.
10m: Yield: 100 mg, 34%. Rf = 0.25. 1H NMR (500 MHz, CDCl3):
δ = 1.10 (d, J = 6.4 Hz, 3 H, CH3), 1.31–1.39 (m, 1 H, 5-Ha), 1.98–
2.05 (m, 1 H, 3-H), 2.09–2.19 (m, 2 H, 4-H, 5-Hb), 2.20–2.34 (m,
2 H, 3a-H, 6-H), 2.76 (t, J = 9.8 Hz, 1 H, 6a-H), 3.14 (dd, J =
0.8 Hz, J = 12.6 Hz, 1 H, 2-H), 3.20–3.57 [dd, J = 3.9 Hz, J =
5.8 Hz, 2 H, (C-4)CH2OH], 3.63 [dd, J = 7.1 Hz, J = 10.8 Hz, 1
H, (C-6)CHaOH], 3.73 [dd, J = 4.6 Hz, J = 10.9 Hz, 1 H, (C-6)
CHbOH], 7.03–7.06 (m, 2 H, 2Ј-H, 6Ј-H), 7.21–7.35 (m, 3 H, 3Ј-
H, 4Ј-H, 5Ј-H) ppm. 13C NMR (125 MHz, CDCl3): δ = 17.4 (CH3),
34.1 (C-5), 44.0 (C-6), 45.9 (C-3), 47.0 (C-4), 50.9 (C-3a), 57.1 (C-
6a), 65.7 [(C-6) CH2OH], 65.9 (C-2), 66.5 [(C-4) CH2OH], 127.1
(C-4Ј), 128.5, 128.7 (C-2Ј, C-3Ј, C-5Ј, C-6Ј), 136.5 (C-1Ј) ppm. FT-
4a: Yield: 182 mg, 15%, colorless oil; Rf = 0.30; tR = 10.17 min.
1H NMR (500 MHz, CDCl3): δ = 0.91 (t, J = 7.2 Hz, 3 H, 3Ј-H),
1.17 [d, J = 6.4 Hz, 3 H, (C-3)CH3], 1.22–1.31 (m, 2 H, 2Ј-Ha, 5-
Ha), 1.34–1.48 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.53–1.68 (m, 2 H, 1Ј-Hb, 3-
H), 1.89 (ddd, J = 1.4 Hz, J = 5.9 Hz, J = 11.2 Hz, 1 H, 2-H),
2.00–2.15 (m, 6 H, 3a-H, 4-H, 5-Hb, CH3COO), 2.22–2.32 (m, 1
H, 6-H), 2.53 (td, J = 9.2 Hz, J = 1.1 Hz, 1 H, 6a-H), 3.57 (dd, J
= 6.5 Hz, J = 10.5 Hz, 1 H, CHaOH), 3.61 (dd, J = 6.5 Hz, J =
10.5 Hz, 1 H, CHbOH), 4.06 (dd, J = 7.1 Hz, J = 10.9 Hz, 1 H,
CHaOOC), 4.24 (dd, J = 5.2 Hz, J = 10.9 Hz, 1 H, CHbOOC) ppm.
13C NMR (125 MHz, CDCl3): δ = 14.3 (3Ј-C), 19.0 [(C-3) CH3],
20.1 (C-2Ј), 20.9 (CH3COO), 30.0 (C-1Ј), 34.5 (C-5), 40.7, 41.7 (C-
3, C-4), 47.5 (C-6), 50.9 (C-3a), 54.3 (C-6a), 57.8 (C-2), 66.5, 66.6
IR (ATR): ν = 3364 cm–1 (s), 2951 (s), 2921 (s), 2870 (s), 1721 (vs),
˜
1496 (m), 1451 (s), 1377 (s), 1051 (vs), 908 (vs), 754 (vs), 646 (s)
cm–1. GC-MS (EI): m/z (%) = 274.4 (18) [M+], 243.4 (11), 173.3
(23), 118.1 (100), 91.1 (38), 79.1 (25), 67.1 (11), 55.1 (8). HRMS
(EI): calcd. for C17H22O3 274.1569, found 274.1552 [M+].
1
10n: Yield: 115 mg, 38%. Rf = 0.29. H NMR (500 MHz, (CD3)2-
(CH OOC, CH OH), 171.1 (COO) ppm. FT-IR (ATR): ν =
˜
2
2
CO): δ = 0.77 (t, J = 7.0 Hz, 3 H, 4Ј-H), 1.11–1.30 (m, 4 H, 2Ј-H,
3Ј-H), 1.44 (dd, J = 4.6 Hz, J = 10.2 Hz, 1 H, 5-Ha), 1.57–1.63 (m,
2 H, 1Ј-H), 2.14–2.37 (m, 4 H, 3-H, 4-H, 5-Hb, 6-H), 2.41 (dt, J =
3.4 Hz, J = 9.3 Hz, 1 H, 3a-H), 2.69 (t, J = 9.6 Hz, 1 H, 6a-H),
2.79–2.92 (m, 2 H, OH), 3.35 (dd, J = 0.9 Hz, J = 11.9 Hz, 1 H,
2-H), 3.51–3.59 [m, 3 H, (C-4)CH2OH, (C-6)CHaOH], 3.69 [dd, J
= 5.3 Hz, J = 10.4 Hz, 1 H, (C-6)CHbOH], 7.13–7.17 (m, 2 H, 2Ј-
H, 6Ј-H), 7.20–7.34 (m, 3 H, 3Ј-H, 4Ј-H, 5Ј-H) ppm. 13C NMR
(125 MHz, (CD3)2CO): δ = 15.1 (C-4Ј), 24.6 (C-3Ј), 29.4 (C-2Ј),
34.9 (C-1Ј), 36.1 (C-5), 46.3, 49.8 (C-4, C-6), 50.6 (C-3a), 51.2 (C-
3), 57.1 (C-6a), 65.6 (C-2), 66.6, 67.6 [(C-4) CH2OH, (C-6)
CH2OH], 128.3 (C-4Ј), 130.0, 130.9 (C-2Ј, C-3Ј, C-5Ј, C-6Ј), 141.1
3453 cm–1 (m), 2955 (s), 2928 (s), 2870 (s), 1728 (vs), 1457 (m),
1366 (s), 1233 (vs), 1167 (m), 1033 (vs), 971 (m), 909 (m), 734 (m),
605 (m) cm–1. GC-MS (EI): m/z (%) = 240.1 (14) [(M – CH3COO)
+], 225.0 (100), 222.1 (35), 183.0 (72), 180.1 (44), 165.0 (62), 147.0
(32), 119.9 (23), 91.0 (29), 78.9 (58), 68.9 (48), 54.9 (67). HRMS
(CI, CH4): calcd. for C16H27O4 283.1909, found 283.1909
[M + H]+.
5a: Yield: 326 mg, 27%, Rf = 0.37; tR = 10.07 min. 1H NMR
(500 MHz, CDCl3): δ = 0.91 (t, J = 7.1 Hz, 3 H, 3Ј-H), 1.17 [d, J
= 6.4 Hz, 3 H, (C-3)CH3], 1.22–1.33 (m, 2 H, 2Ј-Ha, 5-Ha), 1.36–
1.52 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.53–1.70 (m, 2 H, 1Ј-Hb, 3-H), 1.97–
2.02 (m, 1 H, 2-H), 2.04–2.16 (m, 6 H, 3a-H, 4-H, 5-Hb, CH3COO),
2.18–2.25 (m, 1 H, 6-H), 2.63 (t, J = 8.7 Hz, 1 H, 6a-H), 3.55 (dd,
J = 8.2 Hz, J = 10.6 Hz, 1 H, CHaOH), 3.73 (dd, J = 4.2 Hz, J =
10.6 Hz, 1 H, CHbOH), 4.01 (dd, J = 6.1 Hz, J = 9.8 Hz, 1 H,
CHaOOC), 4.03 (dd, J = 5.4 Hz, J = 9.8 Hz, 1 H, CHbOOC) ppm.
13C NMR (125 MHz, CDCl3): δ = 14.3 (C-3Ј), 18.2 [(C-3) CH3],
19.9 (C-2Ј), 20.9 (CH3COO), 29.1 (C-1Ј), 34.9 (C-5), 43.0 (C-3),
43.8, 44.2 (C-4, C-6), 51.4 (C-3a), 57.9, 58.3 (C-2, C-6a), 66.5
(C-1Ј), 219.3 (C-1) ppm. FT-IR (ATR): ν = 3375 cm–1 (s), 2954 (s),
˜
2924 (s), 2859 (s), 1724 (vs), 1496 (m), 1452 (m), 1374 (m), 1240
(s), 1045 (vs), 755 (s), 698 (vs) cm–1. GC-MS (EI): m/z (%) = 316.2
(34) [M+], 298.2 (5), 267.2 (10), 259.1 (25), 241.2 (10), 225.1 (12),
215.1 (39), 160.0 (26), 149.0 (20), 129.1 (16), 118.0 (100), 116.0 (80),
104.0 (69), 91.1 (95), 78.9 (35), 66.9 (24), 55.1 (21). HRMS (EI):
calcd. for C20H28O3 316.2038, found 316.2037 [M+].
1
10o: Yield: 861 mg, 43%. Rf = 0.26. H NMR (500 MHz, (CD3)2-
(CH OOC), 67.8 (CH OH), 171.0 (COO) ppm. FT-IR (ATR): ν =
˜
2
2
CO): δ = 1.57 (dd, J = 5.0 Hz, J = 10.2 Hz, 1 H, 5-Ha), 2.23–2.31
(m, 2 H, 4-H, 5-Hb), 2.42–2.51 (m, 1 H, 6-H), 2.82–2.91 (m, 2 H,
3a-H, 6a-H), 3.24–3.91 [m, 1 H, (C-4)CHaOH], 3.32–3.39 [m, 2 H,
3-H, (C-4)CHbOH], 3.58–3.63 [m, 1 H, (C-6)CHaOH], 3.76–3.80
[m, 1 H, (C-6)CHbOH], 3.99 (dd, J = 0.8 Hz, J = 13.2 Hz, 1 H, 2-
H), 7.06–7.09 (m, 2 H, 4Ј-H, 4ЈЈ-H), 7.12–7.39 (m, 8 H, 2Ј-H, 2ЈЈ-
H, 3Ј-H, 3ЈЈ-H, 5Ј-H, 5ЈЈ-H, 6Ј-H, 6ЈЈ-H) ppm. 13C NMR
(125 MHz, (CD3)2CO): δ = 36.1 (C-5), 46.6 (C-6), 48.8 (C-4), 52.9
(C-3a), 56.8 (C-6a), 58.0 (C-3), 66.5 [(C-6) CH2OH], 66.9 (C-2),
3447 cm–1 (m), 2955 (s), 2928 (s), 2871 (s), 1728 (vs), 1457 (m),
1368 (s), 1229 (vs), 1171 (m), 1032 (vs), 973 (m), 901 (m) cm–1. GC-
MS (EI): m/z (%) = 282.0 (1) [M+], 267.0 (2), 240.1 (22), 225.0
(100), 180.1 (13), 165.0 (16), 146.9 (17), 139.0 (13), 119.0 (8), 90.9
(10), 78.9 (18), 68.9 (11), 54.9 (23). HRMS (CI, CH4): calcd. for
C16H27O4 283.1909, found 283.1909 [M + H]+.
4b: Yield: 80.7 mg, 87%, colorless oil; Rf = 0.37; tR = 11.37 min.
1H NMR (500 MHz, CDCl3): δ = 0.91 (t, J = 6.0 Hz, 3 H, 4ЈЈ-H),
67.3 [(C-4) CH2OH], 128.3, 128.4 (C-4Ј, C-4ЈЈ), 129.6, 129.9, 130.2, 0.93 (d, J = 6.7 Hz, 3 H, 3Ј-H), 1.18–1.56 (m, 10 H, 1Ј-Ha, 1ЈЈ-H,
130.9 (C-2Ј, C-2ЈЈ, C-3Ј, C-3ЈЈ, C-5Ј, C-5ЈЈ, C-6Ј, C-6ЈЈ), 139.4 (C- 2Ј-H, 2ЈЈ-H, 3ЈЈ-H, 5-Ha), 1.58–1.65 (m, 1 H, 1Ј-Hb), 1.68–1.74 (m,
1ЈЈ), 143.5 (C-1Ј), 217.9 (C-1) ppm. FT-IR (ATR): ν = 3363 cm–1
1 H, 3-H), 1.88–1.96 (m, 1 H, 4-H), 1.99–2.03 (m, 1 H, 2-H), 2.05–
˜
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2221

A. Becheanu, A. Baro, S. Laschat, W. Frey
FULL PAPER
2.10 (m, 4 H, CH3COO, 5-Hb), 2.11–2.17 (m, 1 H, 3a-H), 2.34– (16), 93.0 (29), 79.0 (48), 68.9 (40), 55.0 (54). HRMS (EI): calcd.
2.42 (m, 1 H, 6-H), 2.55 (dt, J = 0.9 Hz, J = 8.0 Hz, 1 H, 6a-H), for C17H28O4 296.1988, found 296.2000 [M + H]+.
3.56 [dd, J = 6.9 Hz, J = 10.5 Hz, 1 H, (C-4)CHa], 3.69 [dd, J =
5d: tR = 10.58 min. GC-MS (EI): m/z (%) = 296.3 (4) [M+], 281.2
5.6 Hz, J = 10.6 Hz, 1 H, (C-4)CHb], 4.07 [dd, J = 6.9 Hz, J =
(9), 240.2 (11), 225.1 (100), 180.1 (10), 165.0 (14), 147.0 (20), 119.0
11.0 Hz, 1 H, (C-6)CHa], 4.14 [dd, J = 5.9 Hz, J = 10.9 Hz, 1 H,
(10), 93.0 (12), 79.0 (18), 69.0 (10), 55.0 (22). HRMS (EI): calcd.
(C-6)CHb] ppm. 13C NMR (125 MHz, CDCl3): δ = 14.0, 14.2 (C-
for C17H28O4 296.1988, found 296.2000 [M + H]+.
3Ј, C-4ЈЈ), 20.4 (C-3ЈЈ), 20.9 (COOCH3), 23.0 (C-2Ј), 29.0 (C-2ЈЈ),
4e: Yield: 66.0 mg, 79%, colorless oil; Rf = 0.36; tR = 11.80 min.
1H NMR (500 MHz, CDCl3): δ = 0.90 (t, J = 7.0 Hz, 3 H, 4ЈЈ-H),
0.93 (t, J = 6.8 Hz, 3 H, 4Ј-H), 1.16–1.56 (m, 12 H, 1Ј-Ha, 1ЈЈ-H,
2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 5-Ha), 1.60–1.67 (m, 1 H, 1Ј-Hb), 1.68–
1.74 (m, 1 H, 3-H), 1.88–1.96 (m, 1 H, 4-H), 1.98–2.03 (m, 1 H, 2-
H), 2.05–2.10 (m, 4 H, 5-Hb, CH3COO), 2.11–2.17 (m, 1 H, 3a-H),
2.35–2.42 (m, 1 H, 6-H), 2.55 (dt, J = 0.9 Hz, J = 8.7 Hz, 1 H, 6a-
H), 3.56 [dd, J = 6.9 Hz, J = 10.6 Hz, 1 H, (C-4)CHa], 3.69 [dd, J
= 5.6 Hz, J = 10.6 Hz, 1 H, (C-4)CHb], 4.07 [dd, J = 6.9 Hz, J =
10.8 Hz, 1 H, (C-6)CHa], 4.14 [dd, J = 5.9 Hz, J = 10.8 Hz, 1 H,
(C-6)CHb] ppm. 13C NMR (125 MHz, CDCl3): δ = 13.9, 14.0 (C-
4Ј, C-4ЈЈ), 20.9 (CH3COO), 22.8, 23.0 (C-3Ј, C-3ЈЈ), 29.0, 29.3, 29.5
(C-1Ј, C-2Ј, C-2ЈЈ), 34.1 (C-5), 35.1 (C-1ЈЈ), 40.3 (C-6), 44.6 (C-3),
48.0, 48.3 (C-3a, C-4), 54.8, 55.2 (C-2, C-6a), 65.7, 67.0 (CH2OOC,
32.1 (C-1Ј), 34.0 (C-5), 35.1 (C-1ЈЈ), 40.3 (C-6), 44.7 (C-3), 48.0,
48.3 (C-3a, C-4), 54.8, 55.1 (C-2, C-6a), 65.7, 67.0 (CH2OOC,
CH OH), 171.1 (COO) ppm. FT-IR (ATR): ν = 3460 cm–1 (m),
˜
2
2956 (s), 2927 (s), 2871 (s), 1728 (vs), 1464 (m), 1366 (s), 1234 (vs),
1034 (s), 905 (m), 730 (s), 648 (m), 606 (m) cm–1. GC-MS (EI):
m/z (%) = 281.1 (3) [(M – CH3CO)+], 264.1 (15), 225.2 (100), 183.1
(44), 165.1 (58), 147.0 (20), 118.9 (12), 105.0 (12), 93.1 (17), 79.0
(33), 67.0 (16), 55.0 (32). HRMS (EI): calcd. for C19H32O4
324.2301, found 324.2285 [M+].
5b: tR = 11.22 min. GC-MS (EI): m/z (%) = 282.3 (4) [(M –
CH2CO)+], 225.1 (100), 181.1 (6), 165.1 (13), 147.0 (16), 119.0 (6),
105.0 (4), 93.0 (6), 79.0 (11), 67.0 (6), 55.0 (14). HRMS (EI): calcd.
for C19H32O4 324.2301, found 324.2285 [M+].
CH OH), 171.1 (COO) ppm. FT-IR (ATR): ν = 3441 cm–1 (m),
4c: Yield: 158 mg, 84%, colorless oil; Rf = 0.31; tR = 12.61 min.
1H NMR (250 MHz, CDCl3): δ = 0.76 (t, J = 7.1 Hz, 3 H, 3Ј-H),
1.00–1.44 (m, 4 H, 1Ј-Ha, 2Ј-H, 5-Ha), 1.47–1.64 (m, 1 H, 1Ј-Hb),
2.00–2.24 (m, 5 H, 4-H, 5-Hb, CH3COO), 2.30–2.46 (m, 1 H, 6-H),
2.49–2.62 (m, 2 H, 2-H, 3a-H), 2.64–2.80 (m, 2 H, 3-H, 6a-H), 3.35
[d, J = 6.3 Hz, 2 H, (C-4)CH2], 4.11 [dd, J = 7.0 Hz, J = 11.0 Hz,
1 H, (C-6)CHa], 4.30 [dd, J = 5.2 Hz, J = 11.0 Hz, 1 H, (C-6)CHb],
7.22–7.38 (m, 5 H, 2ЈЈ-H, 3ЈЈ-H, 4ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H) ppm. 13C
NMR (63 MHz, CDCl3): δ = 14.2 (C-3Ј), 20.0 (C-2Ј), 21.0
(CH3COO), 30.1 (C-1Ј), 34.6 (C-5), 41.0 (C-6), 47.6 (C-4), 51.6 (C-
3a), 54.4 (C-3, C-6a), 58.2 (C-2), 66.2, 66.6 (CH2OOC, CH2OH),
127.1 (C-4ЈЈ), 127.5, 129.0 (C-2ЈЈ, C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 142.3 (C-
˜
2
2955 (s), 2926 (s), 2858 (s), 1732 (vs), 1465 (m), 1366 (s), 1237 (vs),
1035 (s), 904 (s), 727 (s), 649 (m) cm–1. GC-MS (EI): m/z (%) =
338.5 (2) [M+], 278.2 (10), 225.1 (100), 203.1 (10), 183.1 (46), 165.0
(29), 147.0 (12), 132.9 (5), 119.1 (7), 105.0 (8), 91.0 (14), 79.0 (19),
67.0 (15), 55.0 (30). HRMS (EI): calcd. for C20H34O4 338.2457,
found 338.2436 [M+].
5e: tR = 11.66 min. GC-MS (EI): m/z (%) = 281.1 (8) [(M –
C4H9)+], 225.1 (100), 183.1 (5), 165.0 (14), 147.0 (15), 137.0 (4),
118.9 (7), 90.9 (7), 79.0 (14), 67.0 (8), 54.9 (19). HRMS (EI): calcd.
for C20H34O4 338.2457, found 338.2436 [M+].
1ЈЈ), 171.2 (COO), 217.7 (C-1) ppm. FT-IR (ATR): ν = 3440 cm–1
4f: Yield: 80.1 mg, 74%, colorless oil; Rf = 0.32; tR = 12.99 min.
1H NMR (250 MHz, CDCl3): δ = 0.77 (t, J = 6.9 Hz, 3 H, 4Ј-H),
0.99–1.46 (m, 6 H, 1Ј-Ha, 2Ј-H, 3Ј-H, 5-Ha), 1.49–1.65 (m, 1 H, 1Ј-
Hb), 2.04–2.24 (m, 5 H, 4-H, 5-Hb, CH3COO), 2.32–2.46 (m, 1 H,
6-H), 2.48–2.62 (m, 2 H, 2-H, 3a-H), 2.65–2.80 (m, 2 H, 3-H, 6a-
H), 3.35 [d, J = 6.3 Hz, 2 H, (C-4)CH2], 4.11 [dd, J = 7.0 Hz, J =
11.0 Hz, 1 H, (C-6)CHa], 4.30 [dd, J = 5.2 Hz, J = 11.0 Hz, 1 H,
(C-6)CHb], 7.22–7.39 (m, 5 H, 2ЈЈ-H, 3ЈЈ-H, 4ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H)
˜
(m), 2955 (s), 2928 (s), 2871 (s), 1729 (vs), 1495 (m), 1454 (m), 1366
(s), 1237 (vs), 1158 (m), 1074 (m), 1034 (s), 970 (m), 906 (s), 761
(s), 731 (s), 701 (vs), 648 (m) cm–1. GC-MS (EI): m/z (%) = 302.2
(16) [(M – C3H6)+], 284.1 (57), 242.1 (30), 224.1 (14), 211.0 (12),
182.1 (15), 169.9 (10), 155.0 (12), 146.0 (19), 130.9 (17), 116.9 (74),
104.0 (32), 90.9 (100), 78.9 (35), 67.0 (11), 54.9 (22). HRMS (EI,
CH4): calcd. for C21H28O4 344.1988, found 344.1986 [M+].
ppm. 13C NMR (63 MHz, CDCl3):
δ = 13.7 (C-4Ј), 20.9
5c: tR = 12.48 min. GC-MS (EI): m/z (%) = 301.2 (70) [(M –
C3H7)+], 284.2 (28), 242.2 (46), 225.1 (21), 201.0 (25), 183.0 (25),
167.1 (12), 158.0 (25), 146.0 (32), 117.0 (90), 104.0 (57), 91.0 (100),
79.0 (52), 67.0 (16), 55.0 (28). HRMS (EI, CH4): calcd. for
C21H28O4 344.1988, found 344.1986 [M+].
(CH3COO), 22.6 (C-3Ј), 27.3 (C-2Ј), 28.7 (C-1Ј), 34.5 (C-5), 40.9
(C-6), 47.5 (C-4), 51.5 (C-3a), 54.2, 54.3 (C-3, C-6a), 58.2 (C-2),
66.1, 66.5 (CH2OOC, CH2OH), 127.1 (C-4ЈЈ), 127.4, 128.8 (C-2ЈЈ,
C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 142.1 (C-1ЈЈ), 171.1 (COO), 217.6 (C-1) ppm.
FT-IR (ATR): ν = 3433 cm–1 (m), 2954 (s), 2928 (s), 2859 (s), 1730
˜
1
4d: Yield: 8 mg, 43%, colorless oil; Rf = 0.39; tR = 10.66 min. H
(vs), 1495 (m), 1454 (m), 1366 (s), 1236 (vs), 1156 (m), 1074 (m),
1033 (s), 967 (m), 905 (s), 760 (s), 727 (s), 701 (vs), 648 (m) cm–1.
GC-MS (EI): m/z (%) = 358.3 (6) [M+], 298.2 (45), 242.1 (30), 224.2
(14), 211.1 (16), 183.1 (20), 160.1 (18), 131.0 (23), 117.0 (64), 104.0
(64), 91.0 (100), 79.0 (30), 67.0 (11), 54.9 (26). HRMS (EI, CH4):
calcd. for C22H30O4 358.2144, found 358.2144 [M+].
NMR (500 MHz, C6D6): δ = 0.89 [d, J = 6.3 Hz, 3 H, (C-3)CH3],
0.91 (t, J = 7.0 Hz, 3 H, 4Ј-H), 0.94–1.02 (m, 1 H, 5-Ha), 1.20–1.32
(m, 3 H, 2Ј-Ha, 3-H, 3Ј-H), 1.33–1.46 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.51–
1.62 (m, 4 H, 1Ј-Hb, 2-H, 3a-H, 4-H), 1.69–1.82 (m, 4 H, CH3COO,
5-Hb), 2.09–2.18 (m, 1 H, 6-H), 2.21 (t, J = 9.3 Hz, 1 H, 6a-H),
3.11 [d, J = 5.7 Hz, 2 H, (C-4)CH2], 4.07 [dd, J = 7.2 Hz, J =
10.9 Hz, 1 H, (C-6)CHa], 4.33 [dd, J = 5.3 Hz, J = 10.9 Hz, 1 H,
(C-6)CHb] ppm. 13C NMR (125 MHz, C6D6): δ = 14.1 (C-4Ј), 18.8
[(C-3) CH3], 20.5 (CH3COO), 23.4 (C-3Ј), 27.8 (C-1Ј), 29.4 (C-2Ј),
34.7 (C-5), 41.1, 41.9 (C-3, C-6), 47.7, 51.0 (C-3a, C-4), 54.4 (C-
6a), 57.9 (C-2), 66.4, 66.8 (CH2OOC, CH2OH), 170.2 (COO), 217.2
5f: tR = 12.87 min. GC-MS (EI): m/z (%) = 358.3 (8) [M+], 301.1
(76), 242.1 (64), 201.1 (25), 183.2 (16), 158.0 (33), 141.0 (14), 117.0
(84), 104.0 (67), 91.0 (100), 79.0 (38), 67.0 (19), 55.0 (43). HRMS
(EI, CH4): calcd. for C22H30O4 358.2144, found 358.2144 [M+].
4g: Yield: 14.9 mg, 36%, colorless oil; Rf = 0.37; tR = 11.19 min.
(C-1) ppm. FT-IR (ATR): ν = 3439 cm–1 (m), 2954 (s), 2927 (s), 1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 6.9 Hz, 3 H, 5Ј-H),
˜
2869 (s), 1729 (vs), 1457 (m), 1366 (s), 1234 (vs), 1166 (m), 1034 1.17 [d, J = 6.6 Hz, 3 H, (C-3)CH3], 1.20–1.35 (m, 6 H, 2Ј-Ha, 3Ј-
(vs), 972 (m), 909 (m), 728 (m), 605 (m) cm–1. GC-MS (EI): H, 4Ј-H, 5-Ha), 1.36–1.51 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.54–1.69 (m, 2
m/z (%) = 296.4 (4) [M+], 281.0 (10), 236.2 (36), 225.2 (100), 205.1
(8), 183.0 (44), 180.1 (41), 165.0 (48), 147.0 (31), 125.0 (12), 119.1
H, 1Ј-Hb, 3-H), 1.86–1.91 (m, 1 H, 3a-H), 2.01–2.16 (m, 6 H,
CH3COO, 2-H, 4-H, 5-Hb), 2.23–2.31 (m, 1 H, 6-H), 2.53 (t, J =
2222
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Eur. J. Org. Chem. 2006, 2215–2225

Highly Functionalized Pentalenes via Intermolecular Pauson–Khand Reaction
FULL PAPER
8.7 Hz, 1 H, 6a-H), 3.55–3.63 [m, 2 H, (C-4)CH2], 4.07 [dd, J =
79.0 (37), 67.0 (11), 55.0 (26). HRMS (EI, CH4): calcd. for
7.1 Hz, J = 10.9 Hz, 1 H, (C-6)CHa], 4.24 [dd, J = 5.2 Hz, J = C23H32O4 372.2301, found 372.2299 [M+].
10.9 Hz, 1 H, (C-6)CHb] ppm. 13C NMR (125 MHz, CDCl3): δ =
14.0 (C-5Ј), 19.0 [(C-3) CH3], 20.9 (CH3COO), 22.4 (C-4Ј), 26.5
(C-2Ј), 27.7 (C-1Ј), 32.1 (C-3Ј), 34.5 (C-5), 40.7 (C-6), 41.7 (C-3),
47.5 (C-4), 50.9 (C-2), 54.3 (C-6a), 57.9 (C-3a), 66.6, 66.7
5i: tR = 13.30 min. GC-MS (EI): m/z (%) = 372.3 (10) [M+], 312.3
(18), 301.1 (63), 282.0 (10), 271.3 (13), 242.0 (84), 224.2 (12), 211.2
(12), 201.1 (30), 183.1 (19), 158.0 (30), 141.0 (18), 130.9 (24), 117.0
(59), 104.0 (74), 91.0 (100), 78.9 (29), 67.0 (24), 55.0 (34). HRMS
(EI, CH4): calcd. for C23H32O4 372.2301, found 372.2299 [M+].
(CH OOC, CH OH), 171.1 (COO) ppm. FT-IR (ATR): ν =
˜
2
2
3448 cm–1 (m), 2953 (s), 2926 (s), 2859 (s), 1729 (vs), 1457 (m),
1366 (s), 1235 (vs), 1166 (m), 1035 (vs), 1034 (s), 907 (m), 727 (m),
647 (m), 606 (m) cm–1. GC-MS (EI): m/z (%) = 310.3 (5) [M+],
295.2 (8), 250.2 (22), 225.1 (100), 183.2 (30), 180.0 (22), 165.0 (35),
147.1 (26), 121.0 (10), 107.0 (14), 91.0 (21), 79.0 (32), 68.9 (36),
55.0 (34). HRMS (EI): calcd. for C18H30O4 310.2144, found
310.2127 [M+].
4j: Yield: 48.2 mg, 49%, colorless oil; Rf = 0.38; tR = 11.72 min.
1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 6.8 Hz, 3 H, 6Ј-H),
1.17 [d, J = 6.5 Hz, 3 H, (C-3)CH3], 1.20–1.36 (m, 8 H, 2Ј-Ha, 3Ј-
H, 4Ј-H, 5Ј-H, 5-Ha), 1.35–1.50 (m, 2 H, 1Ј-Ha, 2Ј-Hb), 1.55–1.68
(m, 2 H, 1Ј-Hb, 3-H), 1.89 (dtd, J = 1.4 Hz, J = 5.7 Hz, J = 6.8 Hz,
1 H, 3a-H), 2.01–2.16 (m, 6 H, CH3COO, 2-H, 4-H, 5-Hb), 2.23–
2.31 (m, 1 H, 6-H), 2.53 (t, J = 8.7 Hz, 1 H, 6a-H), 3.55–3.63 [m,
2 H, (C-4)CH2], 4.06 [dd, J = 7.2 Hz, J = 11.0 Hz, 1 H, (C-6)CHa],
4.23 [dd, J = 5.2 Hz, J = 10.9 Hz, 1 H, (C-6)CHb] ppm. 13C NMR
(125 MHz, CDCl3): δ = 14.0 (C-6Ј), 19.0 [(C-3) CH3], 20.9
(CH3COO), 22.5 (C-5Ј), 26.8 (C-2Ј), 27.7 (C-1Ј), 29.5 (C-4Ј), 31.6
(C-3Ј), 34.5 (C-5), 40.7 (C-6), 41.7 (C-3), 47.5 (C-2), 50.9 (C-4),
54.3 (C-6a), 57.9 (C-3a), 66.5, 66.6 (CH2OOC, CH2OH), 171.1
5g: tR = 11.11 min. GC-MS (EI): m/z (%) = 310.2 (6) [M+], 295.2
(12), 240.1 (13), 225.1 (100), 180.1 (10), 165.0 (16), 147.0 (20), 119.0
(9), 105.0 (8), 93.0 (12), 79.0 (16), 68.9 (11), 55.0 (19). HRMS (EI):
calcd. for C18H30O4 310.2144, found 310.2127 [M + H]+.
4h: Yield: 126 mg, 82%, colorless oil; Rf = 0.35; tR = 12.24 min.
1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 7.0 Hz, 3 H, 5Ј-H),
0.92 (t, J = 6.8 Hz, 3 H, 4ЈЈ-H), 1.18–1.57 (m, 14 H, 1Ј-Ha, 1ЈЈ-H,
2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 4Ј-H, 5-Ha), 1.58–1.66 (m, 1 H, 1Ј-Hb),
1.68–1.74 (m, 1 H, 3-H), 1.89–1.96 (m, 1 H, 4-H), 1.98–2.03 (m, 1
H, 2-H), 2.05–2.10 (m, 4 H, 5-Hb, CH3COO), 2.11–2.17 (m, 1 H,
3a-H), 2.34–2.41 (m, 1 H, 6-H), 2.55 (dt, J = 0.9 Hz, J = 8.5 Hz,
1 H, 6a-H), 3.56 [dd, J = 6.9 Hz, J = 10.5 Hz, 1 H, (C-4)CHa], 3.69
[dd, J = 5.6 Hz, J = 10.5 Hz, 1 H, (C-4)CHb], 4.07 [dd, J = 6.9 Hz,
J = 10.8 Hz, 1 H, (C-6)CHa], 4.14 [dd, J = 5.9 Hz, J = 10.8 Hz, 1
H, (C-6)CHb] ppm. 13C NMR (125 MHz, CDCl3): δ = 13.9 (C-4ЈЈ,
C-5Ј), 20.9 (CH3COO), 22.4, 22.9 (C-3ЈЈ, C-4Ј), 26.8, 28.9, 29.8 (C-
1Ј, C-2Ј, C-2ЈЈ), 31.9 (C-3Ј), 34.0 (C-5), 35.0 (C-1ЈЈ), 40.3 (C-6),
44.6 (C-3), 48.0, 48.2 (C-3a, C-4), 54.7, 55.2 (C-2, C-6a), 65.6, 67.0
(COO) ppm. FT-IR (ATR): ν = 3459 cm–1 (m), 2953 (s), 2925 (s),
˜
2856 (s), 1730 (vs), 1457 (m), 1366 (s), 1236 (vs), 1165 (m), 1035
(vs), 907 (s), 728 (s), 648 (m), 606 (m) cm–1. GC-MS (EI): m/z (%)
= 324.3 (5) [M+], 309.2 (11), 264.3 (19), 240.1 (14), 225.1 (100),
207.0 (15), 183.0 (42), 165.0 (32), 149.0 (24), 119.1 (7), 105.0 (16),
93.0 (22), 78.9 (31), 68.9 (27), 55.0 (34). HRMS (EI): calcd. for
C19H32O4 324.2301, found 324.2279 [M+].
5j: tR = 11.64 min. GC-MS (EI): m/z (%) = 324.2 (4) [M+], 309.2
(16), 240.1 (11), 225.1 (100), 207.0 (9), 180.1 (12), 165.0 (16), 147.0
(17), 119.0 (8), 105.0 (10), 93.0 (12), 79.0 (19), 69.0 (11), 55.0 (21).
HRMS (EI): calcd. for C19H32O4 324.2301, found 324.2279 [M+].
4k: Yield: 177 mg, 68%, colorless oil; Rf = 0.37; tR = 12.69 min.
1H NMR (500 MHz, CDCl3): δ = 0.88 (t, J = 6.8 Hz, 3 H, 6Ј-H),
0.92 (t, J = 6.8 Hz, 3 H, 4ЈЈ-H), 1.20–1.56 (m, 16 H, 1Ј-Ha, 1ЈЈ-H,
2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 4Ј-H, 5-Ha, 5Ј-H), 1.59–1.66 (m, 1 H, 1Ј-
Hb), 1.68–1.74 (m, 1 H, 3-H), 1.89–1.95 (m, 1 H, 4-H), 1.98–2.03
(m, 1 H, 2-H), 2.04–2.10 (m, 4 H, 5-Hb, CH3COO), 2.11–2.18 (m,
1 H, 3a-H), 2.35–2.42 (m, 1 H, 6-H), 2.55 (dt, J = 0.9 Hz, J =
8.1 Hz, 1 H, 6a-H), 3.56 [dd, J = 6.9 Hz, J = 10.5 Hz, 1 H, (C-4)
CHa], 3.69 [dd, J = 5.5 Hz, J = 10.5 Hz, 1 H, (C-4)CHb], 4.07 [dd,
J = 6.9 Hz, J = 10.9 Hz, 1 H, (C-6)CHa], 4.14 [dd, J = 5.9 Hz, J =
10.9 Hz, 1 H, (C-6)CHb] ppm. 13C NMR (125 MHz, CDCl3): δ =
14.0 (C-4ЈЈ, C-6Ј), 20.9 (CH3COO), 22.5, 23.0 (C-3ЈЈ, C-5Ј), 27.1,
28.9, 29.4, 29.8 (C-1Ј, C-2Ј, C-2ЈЈ, C-4Ј), 31.6 (C-3Ј), 34.0 (C-5),
35.1 (C-1ЈЈ), 40.3 (C-6), 44.6 (C-3), 48.0, 48.3 (C-3a, C-4), 54.7,
55.2 (C-2, C-6a), 65.7, 67.0 (CH2OOC, CH2OH), 171.1 (COO),
(CH OOC, CH OH), 171.2 (COO) ppm. FT-IR (ATR): ν =
˜
2
2
3437 cm–1 (m), 2955 (s), 2926 (s), 2858 (s), 1728 (vs), 1465 (m),
1367 (s), 1238 (vs), 1035 (s), 905 (vs), 728 (vs), 648 (m) cm–1. GC-
MS (EI): m/z (%) = 295.4 (12) [(M – C4H9)+], 253.2 (14), 225.1
(100), 204.2 (12), 183.1 (43), 165.1 (39), 147.1 (6), 136.9 (7), 116.9
(8), 107.0 (11), 93.0 (20), 78.9 (20), 67.0 (14), 55.0 (24). HRMS
(EI): calcd. for C21H36O4 352.2614, found 352.2613 [M+].
5h: tR = 12.09 min. GC-MS (EI): m/z (%) = 295.1 (11) [(M –
C4H9)+], 225.1 (100), 183.0 (6), 165.0 (7), 146.9 (15), 118.9 (5),
105.0 (7), 90.9 (11), 79.0 (10), 67.0 (7), 54.9 (16). HRMS (EI): calcd.
for C21H36O4 352.2614, found 352.2613 [M+].
4i: Yield: 59.0 mg, 83%, colorless oil; Rf = 0.32; tR = 13.41 min.
1H NMR (500 MHz, CDCl3): δ = 0.78 (t, J = 6.7 Hz, 3 H, 5Ј-H),
0.99–1.44 (m, 8 H, 1Ј-Ha, 2Ј-H, 3Ј-H, 4Ј-H, 5-Ha), 1.49–1.63 (m, 1
H, 1Ј-Hb), 2.00–2.24 (m, 5 H, 4-H, 5-Hb, CH3COO), 2.32–2.46 (m,
1 H, 6-H), 2.47–2.63 (m, 2 H, 2-H, 3a-H), 2.64–2.80 (m, 2 H, 3-H,
6a-H), 3.34 [d, J = 6.2 Hz, 2 H, (C-4)CH2], 4.11 [dd, J = 7.0 Hz, J
= 11.0 Hz, 1 H, (C-6)CHa], 4.30 [dd, J = 5.2 Hz, J = 11.0 Hz, 1 H,
(C-6)CHb], 7.21–7.39 (m, 5 H, 2ЈЈ-H, 3ЈЈ-H, 4ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 13.8 (C-5Ј), 20.8
(CH3COO), 22.2 (C-4Ј), 26.2 (C-2Ј), 27.6 (C-1Ј), 31.7 (C-3Ј), 34.5
(C-5), 40.8 (C-6), 47.5 (C-4), 51.4 (C-3a), 54.2, 54.3 (C-3, C-6a),
58.3 (C-2), 66.0, 66.5 (CH2OOC, CH2OH), 127.1 (C-4ЈЈ), 127.4,
128.8 (C-2ЈЈ, C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 142.2 (C-1ЈЈ), 171.1 (COO), 217.6
220.4 (C-1) ppm. FT-IR (ATR): ν = 3451 cm–1 (m), 2955 (s), 2925
˜
(s), 2856 (s), 1729 (vs), 1458 (m), 1366 (s), 1236 (vs), 1035 (s), 970
(m), 911 (m), 730 (s), 647 (m) cm–1. GC-MS (EI): m/z (%) = 366.5
(2) [M+], 309.2 (14), 267.3 (10), 225.1 (100), 204.2 (4), 183.1 (41),
165.1 (24), 147.1 (9), 132.9 (4), 119.0 (6), 105.0 (8), 91.0 (12), 79.0
(16), 67.0 (12), 55.0 (24). HRMS (EI): calcd. for C22H38O4
366.2770, found 366.2762 [M+].
5k: tR = 12.56 min. GC-MS (EI): m/z (%) = 309.2 (13) [(M –
C4H9)+], 225.1 (100), 165.0 (10), 147.0 (11), 119.1 (5), 105.0 (5),
93.0 (7), 79.0 (7), 69.0 (4), 55.0 (14). HRMS (EI): calcd. for
C22H38O4 366.2770, found 366.2762 [M+].
(C-1) ppm. FT-IR (ATR): ν = 3444 cm–1 (m), 2926 (s), 2858 (s),
˜
1730 (vs), 1495 (m), 1454 (m), 1366 (s), 1237 (vs), 1155 (m), 1075
(m), 1033 (s), 966 (m), 906 (s), 760 (s), 727 (s), 700 (vs), 647 (m) 4l: Yield: 106 mg, 81%, colorless oil; Rf = 0.28; tR = 13.84 min. 1H
cm–1. GC-MS (EI): m/z (%) = 372.2 (8) [M+], 312.2 (34), 302.2 (22), NMR (500 MHz, CDCl3): δ = 0.81 (t, J = 7.1 Hz, 3 H, 6Ј-H), 1.01–
281.2 (20), 242.1 (35), 224.0 (25), 211.1 (14), 201.1 (34), 181.1 (19),
158.0 (16), 141.0 (14), 130.9 (28), 116.9 (68), 104.0 (65), 91.0 (100),
1.41 (m, 10 H, 1Ј-Ha, 2Ј-H, 3Ј-H, 4Ј-H, 5Ј-H, 5-Ha), 1.52–1.60 (m,
1 H, 1Ј-Hb), 2.05–2.21 (m, 5 H, 4-H, 5-Hb, CH3COO), 2.36–2.44
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2223

A. Becheanu, A. Baro, S. Laschat, W. Frey
(m, 1 H, 6-H), 2.51–2.60 (m, 2 H, 2-H, 3a-H), 2.69 (dd, J = 9.4 Hz, IR (ATR): ν = 3440 cm–1 (m), 3028 (m), 2954 (s), 2925 (s), 2858
FULL PAPER
˜
J = 12.1 Hz, 1 H, 3-H), 2.74 (t, J = 9.3 Hz, 1 H, 6a-H), 3.35 [d, J
= 6.4 Hz, 1 H, (C-4)CH2], 4.11 [dd, J = 7.0 Hz, J = 10.9 Hz, 1 H,
(C-6)CHa], 4.30 [dd, J = 5.2 Hz, J = 11.0 Hz, 1 H, (C-6)CHb], 7.24–
(s), 1732 (vs), 1496 (m), 1453 (m), 1366 (s), 1237 (vs), 1033 (s), 971
(m), 905 (s), 755 (m), 729 (s), 699 (vs), 648 (m) cm–1. GC-MS (EI):
m/z (%) = 358.4 (3) [M+], 298.3 (88), 267.1 (27), 223.2 (22), 189.1
7.37 (m, 5 H, 2ЈЈ-H, 3ЈЈ-H, 4ЈЈ-H, 5ЈЈ-H, 6ЈЈ-H) ppm. 13C NMR (28), 160.1 (68), 118.0 (91), 104.0 (72), 91.0 (100), 79.0 (33), 67.0
(125 MHz, CDCl3): δ = 13.9 (C-6Ј), 20.9 (CH3COO), 22.4 (C-5Ј), (16). HRMS (CI, CH4): calcd. for C22H30O4 358.2144, found
26.5 (C-2Ј), 27.7 (C-1Ј), 29.2 (C-4Ј), 31.4 (C-3Ј), 34.5 (C-5), 40.9 358.2144 [M+].
(C-6), 47.5 (C-4), 51.5 (C-3a), 54.2, 54.3 (C-3, C-6a), 58.3 (C-2),
66.1, 66.5 (CH2OOC, CH2OH), 127.0 (C-4ЈЈ), 127.4, 128.8 (C-2ЈЈ,
5n: tR = 13.13 min. GC-MS (EI): m/z (%) = 358.0 (36) [M+], 301.2
(15), 267.1 (12), 215.2 (21), 160.0 (35), 149.0 (25), 117.0 (100), 103.9
C-3ЈЈ, C-5ЈЈ, C-6ЈЈ), 142.2 (C-1ЈЈ), 171.1 (COO), 217.6 (C-1) ppm.
(62), 90.9 (97), 79.0 (26), 67.0 (16). HRMS (CI, CH4): calcd. for
FT-IR (ATR): ν = 3442 cm–1 (m), 2925 (s), 2856 (s), 1730 (vs),
˜
C22H30O4 358.2144, found 358.2144 [M+].
1495 (m), 1454 (m), 1366 (s), 1238 (vs), 1156 (m), 1033 (s), 969 (m),
4o: Yield: 156 mg, 79%, colorless oil; Rf = 0.22; tR = 14.53 min. 1H
NMR (500 MHz, CDCl3): δ = 1.42 (ddd, J = 8.0 Hz, J = 10.3 Hz, J
= 12.5 Hz, 1 H, 5-Ha), 2.08 (s, 3 H, CH3COO), 2.16–2.24 (m, 1 H,
4-H), 2.27 (td, J = 7.3 Hz, J = 12.5 Hz, 1 H, 5-Hb), 2.57–2.65 (m,
1 H, 6-H), 2.82 (dt, J = 3.7 Hz, J = 9.9 Hz, 1 H, 3a-H), 2.91 (t, J
= 9.6 Hz, 1 H, 6a-H), 3.13 (dd, J = 9.9 Hz, J = 12.7 Hz, 1 H, 3-
H), 3.39 [d, J = 6.3 Hz, 2 H, (C-4)CH2], 3.73 (dd, J = 0.7 Hz, J =
12.7 Hz, 1 H, 2-H), 4.17 [dd, J = 7.0 Hz, J = 11.0 Hz, 1 H, (C-6)
CHa], 4.36 [dd, J = 5.2 Hz, J = 11.0 Hz, 1 H, (C-6)CHb], 6.93–7.30
(m, 10 H, 2Ј-H, 2ЈЈ-H, 3Ј-H, 3ЈЈ-H, 4Ј-H, 4ЈЈ-H, 5Ј-H, 5ЈЈ-H, 6Ј-H,
6ЈЈ-H) ppm. 13C NMR (125 MHz, CDCl3): δ = 20.9 (CH3COO),
34.4 (C-5), 41.0 (C-6), 47.2 (C-4), 50.7 (C-3a), 54.6 (C-6a), 56.7 (C-
3), 65.4 (C-2), 66.0, 66.3 (CH2OOC, CH2OH), 127.0, 127.1 (C-4Ј,
C-4ЈЈ), 127.5, 128.5, 128.6, 128.8 (C-2Ј, C-2ЈЈ, C-3Ј, C-3ЈЈ, C-5Ј, C-
5ЈЈ, C-6Ј, C-6ЈЈ), 136.2 (C-1ЈЈ), 140.5 (C-1Ј), 171.1 (COO), 214.8
905 (s), 760 (s), 725 (s), 700 (vs), 648 (m) cm–1. GC-MS (EI):
m/z (%) = 386.2 (12) [M+], 344.2 (4), 326.3 (32), 302.2 (33), 259.3
(13), 242.1 (36), 224.2 (21), 215.2 (24), 211.1 (24), 195.1 (11), 183.0
(20), 158.0 (18), 131.0 (32), 116.9 (73), 104.0 (82), 91.0 (100), 79.0
(34), 67.0 (14), 55.0 (34). HRMS (EI, CH4): calcd. for C24H34O4
386.2457, found 386.2452 [M+].
5l: tR = 13.73 min. GC-MS (EI): m/z (%) = 386.5 (11) [M+], 326.3
(15), 315.4 (11), 301.2 (61), 242.1 (68), 211.1 (16), 201.1 (36), 183.0
(21), 165.0 (14), 158.1 (22), 141.0 (14), 129.1 (18), 116.9 (61), 103.9
(74), 91.0 (100), 79.0 (26), 69.0 (12), 55.0 (25). HRMS (EI, CH4):
calcd. for C24H34O4 386.2457, found 386.2452 [M+].
4m: Yield: 8.52 mg, 49%, colorless oil; Rf = 0.25; tR = 12.37 min.
1H NMR (500 MHz, CDCl3): δ = 1.14 (d, J = 6.4 Hz, 3 H, CH3),
1.52–1.62 (m, 1 H, 5-Ha), 2.17 (s, 3 H, CH3COO), 2.19–2.28 (m, 3
H, 3-H, 4-H, 5-Hb), 2.35 (t, J = 7.4 Hz, 1 H, 3a-H), 2.44–2.51 (m,
1 H, 6-H), 2.71 (t, J = 9.7 Hz, 1 H, 6a-H), 3.11 (d, J = 12.6 Hz, 1
H, 2-H), 3.40 [dd, J = 7.7 Hz, J = 10.9 Hz, 1 H, (C-4)CHa], 3.62–
3.66 [m, 1 H, (C-4)CHb], 4.13 [dd, J = 7.3 Hz, J = 10.9 Hz, 1 H,
(C-6)CHa], 4.32 [dd, J = 5.1 Hz, J = 10.9 Hz, 1 H, (C-6)CHb],
7.04–7.36 (m, 5 H, 2Ј-H, 3Ј-H, 4Ј-H, 5Ј-H, 6Ј-H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 17.8 (CH3), 20.9 (CH3COO), 34.6 (C-5),
41.0 (C-6), 45.5 (C-3), 47.2 (C-4), 50.8 (C-3a), 54.6 (C-6a), 65.8 (C-
2), 66.4, 66.6 (CH2OOC, CH2OH), 127.0 (C-4Ј), 128.6, 128.7 (C-
2Ј, C-3Ј, C-5Ј, C-6Ј), 136.9 (C-1Ј), 171.1 (COO), 215.9 (C-1) ppm.
(C-1) ppm. FT-IR (ATR): ν = 3443 cm–1 (m), 2920 (m), 2891 (m),
˜
1730 (vs), 1602 (m), 1496 (m), 1452 (m), 1386 (m), 1366 (s), 1236
(vs), 1153 (m), 1135 (m), 1074 (m), 1032 (s), 969 (m), 912 (m), 761
(s), 755 (s), 732 (m), 698 (vs), 645 (m), 606 (m) cm–1. GC-MS (EI):
m/z (%) = 378.2 (32) [M+], 318.1 (4), 281.2 (16), 209.1 (12), 179.1
(40), 165.0 (26), 155.1 (13), 118.0 (100), 105.0 (13), 91.0 (43), 79.0
(20), 67.0 (8), 55.1 (3). HRMS (EI, CH4): calcd. for C24H26O4
378.1831, found 378.1826 [M+].
5o: tR = 14.40 min. GC-MS (EI): m/z (%) = 378.1 (38) [M+], 336.1
(6), 318.3 (5), 281.0 (14), 259.1 (10), 179.1 (48), 165.0 (22), 155.0
(9), 128.9 (10), 117.9 (100), 104.9 (32), 91.0 (43), 78.9 (10). HRMS
(EI, CH4): calcd. for C24H26O4 378.1831, found 378.1826 [M+].
FT-IR (ATR): ν = 3453 cm–1 (m), 2955 (s), 2924 (s), 2855 (m), 1736
˜
(vs), 1454 (m), 1376 (s), 1259 (s), 1244 (s), 1125 (m), 1032 (s), 843
(m), 801 (s), 755 (m), 700 (s) cm–1. GC-MS (EI): m/z (%) = 316.3
(5) [M+], 256.2 (61), 225.2 (32), 209.0 (7), 155.0 (8), 147.1 (11),
118.0 (100), 105.1 (15), 91.0 (44), 79.0 (24), 67.0 (12). HRMS (EI):
calcd. for C19H24O4 316.1675, found 316.1674 [M+].
Supporting Information (see footnote on the first page of this arti-
cle): Protection of the keto group in some derivatives 9 by using
trimethyl orthoformate and Amberlyst-15 to give surprisingly enol
ethers instead of O protection as well as the assignment of acetates
4 and 5 by NMR experiments.
5m: tR = 12.29 min. GC-MS (EI): m/z (%) = 316.2 (42) [M+], 301.1
(7), 258.3 (6), 238.2 (11), 225.2 (12), 197.3 (12), 173.1 (24), 154.9
(17), 143.1 (11), 118.0 (100), 105.1 (26), 91.0 (71), 79.0 (28), 67.0
(12), 55.0 (9). HRMS (EI): calcd. for C19H24O4 316.1675, found
316.1674 [M+].
Acknowledgments
Generous financial support by the Deutsche Forschungsgemein-
schaft, the Fonds der Chemischen Industrie, the Ministerium für
Wissenschaft, Forschung und Kunst des Landes Baden-Württem-
berg and the Deutsche Akademische Austauschdienst (DAAD
award for A. Becheanu) is gratefully acknowledged.
4n: Yield: 19.5 mg, 32%, colorless oil; Rf = 0.23; tR = 13.28 min.
1H NMR (500 MHz, CDCl3): δ = 0.80 (t, J = 6.7 Hz, 3 H, 4ЈЈ-H),
1.09–1.40 (m, 6 H, 1ЈЈ-Ha, 2ЈЈ-H, 3ЈЈ-H), 1.56 (dd, J = 7.2 Hz, J =
13.7 Hz, 2 H, 1ЈЈ-Hb), 2.06 (s, 3 H, CH3COO), 2.07–2.24 (m, 3 H,
3-H, 4-H, 5-Hb), 2.33 (dt, J = 4.1 Hz, J = 9.1 Hz, 1 H, 3a-H), 2.45–
2.56 (m, 1 H, 6-H), 2.71 (t, J = 9.1 Hz, 1 H, 6a-H), 3.23 (d, J =
11.2 Hz, 1 H, 2-H), 3.60 [dd, J = 6.5 Hz, J = 10.5 Hz, 1 H, (C-4)
CHa], 3.67 [dd, J = 5.9 Hz, J = 10.5 Hz, 1 H, (C-4)CHb], 4.12 [dd,
J = 7.1 Hz, J = 10.9 Hz, 1 H, (C-6)CHa], 4.25 [dd, J = 5.5 Hz, J =
10.9 Hz, 1 H, (C-6)CHb], 7.05–7.35 (m, 5 H, 2Ј-H, 3Ј-H, 4Ј-H, 5Ј-
H, 6Ј-H) ppm. 13C NMR (125 MHz, CDCl3): δ = 13.8 (C-4ЈЈ), 20.9
(CH3COO), 22.8 (C-3ЈЈ), 28.6 (C-2ЈЈ), 33.5 (C-1ЈЈ), 34.3 (C-5), 40.8
(C-6), 47.6, 48.2, 48.9 (C-3, C-3a, C-4), 54.8 (C-6a), 63.6 (C-2),
66.1, 66.6 (CH2OOC, CH2OH), 126.9 (C-4Ј), 128.6, 128.8 (C-2Ј, C-
3Ј, C-5Ј, C-6Ј), 137.9 (C-1Ј), 171.1 (COO), 216.5 (C-1) ppm. FT-
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Eur. J. Org. Chem. 2006, 2215–2225

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FULL PAPER
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Received: December 9, 2005
Published Online: March 3, 2006
Eur. J. Org. Chem. 2006, 2215–2225
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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