Endo mode cyclization of 5,6-epoxy-7-octyn-1-ol derivatives

Full text of DOI:10.1021/jo000450+

J . Org. Chem. 2000, 65, 6761-6765
6761
with the stereoselective but not the stereospecific con-
struction of the oxepane derivatives.6
En d o Mod e Cycliza tion of
5,6-Ep oxy-7-octyn -1-ol Der iva tives
Resu lts a n d Discu ssion
Chisato Mukai,* Sumie Yamaguchi, Yu-ichi Sugimoto,
Naoki Miyakoshi, Eiji Kasamatsu, and Miyoji Hanaoka*
The required trans-epoxy and cis-epoxy compounds for
the endo mode cyclization were prepared by conventional
means (Scheme 2). The mono-tert-butyldimethylsilyl (TB-
DMS)-protected alcohol 4 was oxidized under Swern
conditions to afford the labile aldehyde, which was
subsequently exposed to the Horner-Emmons reaction
with ethyl (diethylphosphono)acetate providing the (E)-
ester 5 in 96% yield. Transformation of an ester moiety
of 5 into the alkyne functionality was realizes as follows.
The consecutive reduction of 5 with diisobutylaluminum
hydride (DIBAL-H) and oxidation under Swern condi-
tions produced the enal, which was then exposed to
Corey’s dibromoolefination and base treatment7 to leave
the enyne (E)-6 in 62% overall yield. The introduction of
the trimethylsilyl (TMS) group at the acetylenic terminus
of (E)-6 was followed by acidic hydrolysis to afford (E)-
7a in 67% yield. The phenyl derivative (E)-7b was also
derived from (E)-6 under conventional conditions.8 Ep-
oxidation of (E)-7a with m-chloroperbenzoic acid (mCP-
BA) in methylene chloride gave trans-8a (trans:cis ) 91:
9). The other trans-enynes (E)-7b and (E)-6 afforded
trans-8b (trans:cis ) 81:19) and trans-8c (trans:cis ) 95:
5), respectively, upon treatment with mCPBA and tetra-
n-butylammonium fluoride (TBAF). The primary hydroxy
group of these trans-epoxides 8 was silylated with TMS-
imidazole to provide the trans-9. The cis-congeners 9 for
endo mode cyclization were also prepared from the same
starting material 4 as shown in Scheme 2 (see Experi-
mental Section).
According to the procedure previously described for the
transformation of the epoxy-alkyne derivatives 1 (n ) 1,
2) to tetrahydrofuran and tetrahydropyran frameworks
2,1 trans-8a was treated with Co2(CO)8 in methylene
chloride at room temperature to afford the corresponding
cobalt complex, which was subsequently exposed to a
catalytic amount of BF3‚OEt2 (0.1 equiv) at -78 °C to
furnish a mixture of cis-11a and trans-11a in 16% yield
in a ratio of 54 to 46 (Scheme 3). Changing the Lewis
acid from BF3‚OEt2 to the other Lewis acids such as
SnCl4, TiCl4, and BBr3 were found to be fruitless. The
organic acids such as CF3CO2H and CH3SO3H did not
work well either. Our efforts were then focused on
changing the amounts of the Lewis acid, anticipating
improvement in the chemical yield. Thus increasing the
amount of BF3‚OEt2 from a catalytic to a stoichiometric
Faculty of Pharmaceutical Sciences, Kanazawa University,
Takara-machi 13-1, Kanazawa 920-0934, J apan
cmukai@kenroku.kanazawa-u.ac.jp
Received March 24, 2000
In tr od u ction
In previous papers,1 we reported a new and efficient
procedure for the construction of oxygen-atom containing
heterocycles 2 (n ) 1, 2) possessing the 2-ethynyl-3-
hydroxy functionality as a common structural feature
starting from the epoxy-alkyne derivatives 1. Thus 3,4-
epoxy-5-hexyn-1-ol and 4,5-epoxy-6-heptyn-1-ol deriva-
tives 1 (n ) 1, 2) have become suitable substrates for the
endo mode cyclization to give, upon successive treatment
with dicobaltoctacarbonyl [Co2(CO)8] and a catalytic
amount of Lewis acid2 such as boron trifluoride diethyl
etherate (BF3‚OEt2) at -78 °C, the corresponding ox-
acycles 2 (n ) 1, 2) in a highly stereoselective manner
after demetalation with cerium(IV) ammonium nitrate
(CAN). The exo mode products [i.e., oxetane (n ) 1) and
tetrahydrofuran (n ) 2) derivatives] could never be
detected in this procedure. It should be mentioned that
this procedure proceeded stereospecifically and stereo-
complementarily to provide the oxacycles 2; namely the
trans-epoxide 1 afforded the corresponding 2 having a
cis-2-ethynyl-3-hydroxy substituent, while cis-1 furnished
trans-2-ethynyl-3-hydroxy-2. In addition, this endo mode
cyclization method could be applicable to the aza-
congener 3 (n ) 2)3 ending up with the stereoselective
total synthesis of (()-swainsonine, a representative in-
dolizidine alkaloid.
The next phase of this program was to confirm whether
this newly developed endo mode cyclization4 could be
applied to the construction of larger ring-sized oxacycles
such as the seven-membered oxacycle 2 (n ) 3) (oxepane
ring system) and the eight-membered one 2 (n ) 4)
(oxocane ring system). Therefore, our efforts are directed
toward investigating the Co2(CO)8-mediated5 endo mode
cyclization of 5,6-epoxy-7-octyn-1-ol species 1 (n ) 3)
leading to the corresponding oxepane derivatives with
the 2-ethynyl-3-hydroxy functionality. This paper deals
* To whom correspondence should be addressed. Chisato Mukai:
tel: +81-76-234-4411, fax: +81-76-234-4410.
(1) (a) Mukai, C.; Ikeda, Y.; Sugimoto, Y.; Hanaoka, M. Tetrahedron
Lett. 1994, 35, 2179. (b) Mukai, C.; Sugimoto, Y.; Ikeda, Y.; Hanaoka,
M. Tetrahedron Lett. 1994, 35, 2183. (c) Mukai, C.; Sugimoto, Y. Ikeda,
Y.; Hanaoka, M. J . Chem. Soc., Chem. Commun. 1994, 1161. (d) Mukai,
C.; Sugimoto, Y.; Ikeda, Y.; Hanaoka, M. Tetrahedron 1998, 54, 823.
(2) Nicholas, K. M. Acc. Chem. Res. 1987, 20, 207.
(6) Review for synthesis of of seven-membered oxacycles: (a) Boyd,
D. R. In Comprehensive Heterocyclic Chemistry; Lwowski, W., Ed.;
Pergamon: Oxford, 1984; Vol. 7, p 547. (b) Hassenruck, K.; Martin H.
D. Synthesis 1988, 569. (c) Moody, C. J .; Davies, M. J . In Studies in
Natural Products Chemistry; Atta-ur-Rahman, Ed.; Elsevier: New
York, 1992; Vol. 10, p 201. (d) Burns, C. J . Contemp. Org. Synth. 1994,
1, 23. (e) Wlliott, M. C. Contemp. Org. Synth. 1994, 1, 457. (f) Alvarez,
E.; Candenas, M.-L.; Perez, R.; Ravelo, J . L.; Martin, J . D. Chem. Rev.
1995, 95, 1953. (g) Belen′kll, L. I. In Comprehensive Heterocyclic
Chemistry II; Katritzky, A. R., Rees, C. W., Scriven, E. F., Eds.;
Pergamon: Oxford, 1996; p 45. (h) Nicolaou, K. C. Angew. Chem., Int.
Ed. Engl. 1996, 35, 589. (i) Hoberg, J . O. Tetrahedron 1998, 54, 12631,
and references therein.
(3) Mukai, C.; Sugimoto, Y.; Miyazawa, K.; Yamaguchi, S.; Hanaoka,
M. J . Org. Chem. 1998, 63, 6281.
(4) Endo mode cyclization for the preparation of seven-membered
oxacycles: (a) Matsukura, H.; Morimoto, M.; Koshino, H.; Nakata, T.
Tetrahedron Lett. 1997, 38, 5545. (b) Fujiwara, K.; Mishima, H.;
Amano, A.; Tokiwano, T.; Murai, A. Tetrahedron Lett. 1998, 39, 393.
(5) Co2(CO)8-mediated construction of seven-membered oxacycles:
(a) Tanaka, S.; Isobe, M. Tetrahedron Lett. 1994, 35, 7801. (b)
Hosokawa, S.; Isobe, M. Synlett 1995, 1179. (c) Palazon, J . M.; Martin,
V. S. Tetrahedron Lett. 1996, 36, 3549.
(7) Corey, E. J .; Fuchs, P. L. Tetrahedron Lett. 1972, 3769.
(8) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975,
4467.
10.1021/jo000450+ CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/07/2000

6762 J . Org. Chem., Vol. 65, No. 20, 2000
Notes
Sch em e 1
a cis-selective manner (cis-11b:trans-11b ) 78:22) (entry
2). However, the trans-epoxy derivative 8c without a
substituent at the triple bond terminus gave only an
intractable mixture for some unknown reason (entry 3).
It is known that the trimethylsiloxy group can serve
as a surrogate for the free hydroxy functionality, for
example, in the transformation of the carbonyl function-
ality into acetal species.9 Therefore, we next attempted
the ring closure of the TMS-derivatives, trans-9, hoping
to improve the chemical yield as well as the stereoselec-
tivity. The obtained results are presented in Table 1
(entries 4-6). The exposure of trans-9a under standard
conditions [treatment with Co2(CO)8 and 3.0 equiv of BF3‚
OEt2] gave 11a in 75% yield (entry 4), although the level
of stereoselectivity was the same as that observed in the
reaction of 8a (entry 1). Similarly, trans-9b afforded 11b
in a higher yield (62%) compared to the case of 8b. It
would be noteworthy that trans-9c could be converted
into the oxepane skeleton 11c, although the chemical
yield (20%) is far from being satisfactory (entry 6). This
was not the case when trans-8c was exposed to the ring
closure conditions leading to an intractable mixture
(entry 3). Similar treatment of cis-9 afforded the corre-
sponding 11 in a cis-selective manner instead of in a
trans-selective manner (entries 7-9).
Sch em e 2
There are several features that should be pointed out:
(i) Endo mode cyclization proceeded in acceptable yields,
and the corresponding exo mode products could not be
isolated from the reaction mixture. Complete control of
the regioselectivity was thus realized as anticipated. (ii)
Improvement of the chemical yields was made by intro-
duction of the TMS group10 on the primary hydroxy group
of the epoxy-alcohol derivatives. (iii) Although stereose-
lective construction of the oxepane frameworks with a
2,3-cis-substituents were achieved from both the trans-
and cis-epoxy derivatives 9 through the endo mode
cyclization, the degree of stereoselectively was lower than
those of 2 (n ) 1, 2),1 and no stereospecificity could be
observed. Similar degree of cis-selectivity (cis:trans ) ca.
70:30) recorded in all cases as well as nonstereospecificity
might tentatively be interpreted in the terms of inter-
mediacy of the common propynyl cation species.11 The
ring opening of the epoxy moiety of both cis- and trans-
5,6-epoxy-7-octyn-1-ol derivatives 8 and 9 assisted by a
Lewis acid would lead to the common cobalt-complexed
carbenium ion intermediates,11 which then collapse to the
ring-closed product 11 in a cis-selective manner, although
the reason for the preferential formation of cis-product
over trans-one is uncertain.
Sch em e 3
Ta ble 1. Rin g Closu r e of Ep oxid es 8, 9
product ratioa
cis:trans
entry substrate product
R
yieldb (%)
1
2
3
4
5
6
7
8
9
trans-8a c
trans-8bd
trans-8ce
trans-9a c
trans-9bf
trans-9cg
cis-9a
11a
11b
-
11a
11b
11c
11a
11b
11c
TMS
Ph
H
TMS
Ph
H
TMS
Ph
H
72:28
78:22
-
70:30
78:22
68:32
69:31
78:22
72:28
62
44
0
75
62
20
76
56
33
To confirm the limitation of this endo mode cyclization,
we next investigated the ring closure of the one carbon-
elongated epoxides 12 and 1312 under the conditions
described above. Thus the treatment of 12 and 13,
prepared from hexanediol according to the method de-
picted in Scheme 2, with Co2(CO)8 was followed by
exposure to BF3‚OEt2 resulting in an intractable mixture.
Unfortunately the formation of the desired eight-mem-
bered oxacycle 14 could never be detected. On the basis
cis-9bh
cis-9ch
a
b
Ratio of each isomer isolated by chromatography. Isolated
yields. c A mixture (trans:cis ) 91:9) was used. A mixture (trans:
d
cis ) 81:19) was used. e A mixture (trans:cis ) 95:5) was used.f A
g
mixture (trans:cis ) 83:17) was used. A mixture (trans:cis ) 93:
h
7) was used. A mixture (cis:trans ) 93:7) was used.
amount gave 11a in 33% (cis-11a :trans-11a ) 55:45).
When 3.0 equiv of BF3‚OEt2 was employed, the ring
closed product 11a was stereoselectively obtained in a
higher yield (62%, cis-11a :trans-11a ) 72:28) (Table 1,
entry 1). This condition (3.0 equiv of BF3‚OEt2) could be
used for the ring closure of trans-8b having a phenyl
substituent at the acetylenic terminus to yield the
oxepane derivative 11b in a rather lower yield (44%) in
(9) Tsunoda, T.; Suzuki, M.; Noyori, R. Tetrahedron Lett. 1980, 21,
1357.
(10) The reason for the improvment of chemical yields by introduc-
tion of the TMS group is so far uncertain.
(11) (a) Schreiber, S. L.; Sammakia, T.; Crowe, W. E. J . Am. Chem.
Soc. 1986, 108, 3128. (b) Schreiber, S. L.; Klimas, M. T.; Sammakia,
T. J . Am. Chem. Soc. 1987, 109, 5749.
(12) Spectral data of 12 and 13 are presented in Supporting
Information.

Notes
J . Org. Chem., Vol. 65, No. 20, 2000 6763
(diethylphosphono)acetate (10.0 mL, 50.4 mmol), and the mix-
ture was stirred for 1 h. A solution of the crude aldehyde in THF
(20.0 mL) was then added to a solution of the ylide thus adjusted
in THF at 0 °C, and the mixture was stirred for 10 min at room
temperature, quenched by addition of saturated aqueous NH4-
Cl, and extracted with AcOEt. The extract was dried and
concentrated to give a residue, which was chromatographed with
hexane-AcOEt (15:1) to afford 5 (12.6 g, 96%) as a colorless oil:
Sch em e 4
1
IR 1707, 1653 cm-1; H NMR δ 6.96 (dt, 1H, J ) 15.6, 6.8 Hz),
5.18 (dt, 1H, J ) 15.6, 1.5 Hz), 4.18 (q, 2H, J ) 6.8 Hz), 3.61 (t,
2H, J ) 5.9 Hz), 2.21 (qd, 2H, J ) 6.8, 1.5 Hz), 1.58-1.51 (m,
4H), 1.28 (t, 3H, J ) 6.8 Hz), 0.89 (s, 9H), 0.04 (s, 6H); 13C NMR
δ 166.70, 149.11, 121.40, 62.73, 60.11, 32.20, 31.92, 25.93, 24.37,
18.33, 14.27, -5.34; MS m/z 286 (M+, 0.5). Anal. Calcd for
C15H30O3Si: C, 62.89; H, 10.55. Found: C, 62.53; H, 10.63.
(3E)-8-(ter t-Bu tyld im eth ylsiloxy)-3-octen -1-yn e [(E)-6].
To a solution of 5 (6.08 g, 21.2 mmol) in dry hexane (100 mL)
was gradually added DIBAL-H (1.0 M hexane solution; 47.0 mL,
47.0 mmol) at -78 °C. The reaction mixture was kept at the
same temperature for 5 min, quenched with water and saturated
aqueous Na2SO4, and filtrated by suction. The filtrate was
extracted with AcOEt, which was washed with water and brine,
dried, and concentrated to dryness. The residue was passed
through a short pad of silica gel with hexane-AcOEt (8:1) to
of these experimental results in combination with the
previous observation,1 it would be concluded that the
newly developed endo mode ring closure method can be
successfully applied to the construction of five-, six-, and
seven-membered oxygen atom-containing heterocycles,
but not for that of medium-sized oxygen-containing
heterocycles involving oxocane species (eight-membered
oxacycles).
Upon direct exposure to a catalytic amount of BF3‚OEt2
(0.1 equiv) in methylene chloride at -78 °C, trans-8c gave
a mixture of ring-closed products which was subsequently
acetylated to furnish the exo mode product 15 in 71%
yield with inverted stereochemistry at the homopropynyl
position of 8c in a highly stereoselective manner together
with a small amount of the endo mode product 16 (5%)
with inversion of configuration at the propynyl position
(Scheme 4). The cis-congener, cis-8c, exclusively provided
the exo mode product 17 in 82% yield as expected. These
results in the control experiments were in good ac-
cordance with the prediction base on the previous works1
and indicated that cobalt complexation of the epoxy-
alcohol derivatives is mandatory for exclusive endo mode
cyclization.
In summary, we have described a new procedure for
the stereoselective synthesis of cis-3-hydroxy-2-ethynyl-
oxepane derivatives from 5,6-epoxy-7-octyn-1-ols through
the endo mode cyclization mediated by Co2(CO)8. This
result, in combination with the previous studies, dem-
onstrates that the Co2(CO)8-mediated endo mode cycliza-
tion can be applicable to the construction of tetrahydro-
furan, tetrahydropyran, and oxepane skeletons possessing
a 2-ethynyl-3-hydroxy substituent as a common struc-
tural feature.
give the alcohol [4.94 g, 96%; IR 3613, 1669 cm-1 1H NMR δ
;
5.69 (dt, 1H, J ) 15.1, 6.4 Hz), 5.64 (dt, 1H, J ) 15.1, 5.4 Hz),
4.08 (d, 2H, J ) 5.4 Hz), 3.60 (2H, t, J ) 6.4 Hz), 2.06 (q, 2H, J
) 6.4 Hz), 1.55-1.50 (m, 2H), 1.46-1.39 (m, 2H), 1.35 (s, 1H),
0.89 (s, 9H), 0.04 (s, 6H)]. The crude alcohol thus prepared was
oxidized under Swern conditions described for conversion of 4
to 5 to give the crude enal. To a solution of PPh3 (23.4 g, 89.1
mol) in CH2Cl2 (100 mL) was added CBr4 (1.48 g, 44.6 mmol) in
CH2Cl2 (100 mL) and Et3N (5.40 mL, 40.6 mmol) at 0 °C, and
the reaction mixture was stirred for 30 min. A solution of the
crude enal in CH2Cl2 (30 0.0 mL) was then added to a solution
of the ylide in CH2Cl2 solution thus adjusted 0 °C, and stirring
was continued for 2 h at room temperature. Hexane was added
to the reaction mixture, and the resulting precipitates were
filtered off. The filtrate was concentrated and diluted with
hexane. After removal of the precipitates again, the filtrate was
concentrated to give the crude dibromoolefin derivative. To a
solution of the crude dibromoolefin derivative in THF (200 mL)
was added n-BuLi in hexane (1.46 M, 29.7 mL, 43.4 mmol) at
-78 °C, and the reaction mixture was stirred for 1 h at the same
temperature and then at room temperature for an additional 1
h. The reaction mixture was quenched by addition of water,
extracted with Et2O, which was washed with water and brine,
dried, and concentrated to dryness. Chromatography of the
residue with hexane-AcOEt (50:1) afforded (E)-6 (3.11 g, 62%
1
overall yield from 5) as a colorless oil: IR 3307, 2102 cm-1; H
NMR δ 6.25 (dt, 1H, J ) 16.1, 6.8 Hz), 5.46 (dq, 1H, J ) 16.1,
2.0 Hz), 3.60 (t, 2H, J ) 6.4 Hz), 2.78 (d, 1H, J ) 2.0 Hz), 2.13
(qd, 2H, J ) 6.8, 2.0 Hz), 1.55-1.50 (m, 2H), 1.48-1.42 (m, 2H),
0.89 (s, 9H), 0.04 (s, 6H); 13C NMR δ 146.67, 108.63, 82.52, 75.62,
62.80, 32.76, 32.17, 25.95, 24.85, 18.33, -5.32; MS m/z 238 (M+,
0.5). HRMS calcd for C14H26OSi 238.1753, found 238.1751.
7-(ter t-Bu tyld im eth ylsiloxy)-2-h ep tyn -1-ol (10). The al-
cohol 4 (1.00 g, 4.58 mmol) was successively oxidized under
Swern conditions and exposed to Cory’s dibromoolefination
conditions as described for conversion of 5 to (E)-6 to give the
crude 1,1-dibromo-6-(tert-butyldimethylsiloxy)hex-1-ene. n-BuLi
in hexane (1.52 M, 6.60 mL, 10.1 mmol) was added to a solution
of the crude dibromo derivative in THF (46.0 mL) at -78 °C.
After stirring for 1 h at the same temperature, the reaction was
quenched by addition of paraformaldehyde (413 mg, 13.7 mmol).
The reaction mixture was stirred for 3 h at room temperature,
diluted with Et2O, and washed with water. The organic layer
was washed with brine, dried, and concentrated to dryness.
Chromatography of the residue with hexane-AcOEt (5:1) af-
forded 10 (730 mg, 66%) as a colorless oil: IR 3609, 3425, 2224
Exp er im en ta l Section
Melting points are uncorrected. IR spectra were measured in
CHCl3. 1H NMR spectra were taken in CDCl3. CHCl3 (7.26 ppm)
was used as an internal standard for silyl compounds. TMS was
employed as an internal standard for other compounds. 13C NMR
spectra were recorded in CDCl3 with CHCl3 (77.00 ppm) as an
internal standard. CH2Cl2 was freshly distilled from phosphorus
pentaoxide, and THF was from sodium diphenyl ketyl, prior to
use. All reactions were carried out under nitrogen atmosphere
otherwise stated. Silica gel (silica gel 60, 230-400 mesh, Merck)
was used for chromatography. Organic extracts were dried over
anhydrous Na2SO4.
Eth yl 7-(ter t-Bu tyld im eth ysiloxy)-2-h ep ten oic Acid (5).
A solution of DMSO (7.10 mL, 100 mmol) in CH2Cl2 (15.0 mL)
was added to a solution of oxalyl chloride (4.40 mL, 50.4 mmol)
in CH2Cl2 (230 mL) at -78 °C over a period of 5 min. After the
mixture was stirred for 15 min, a solution of the alcohol 4 (10.0
g, 45.8 mmol) was added to the CH2Cl2 solution, and the reaction
mixture was stirred at the same temperature for an additional
1 h. Et3N (32.0 mL, 229 mmol) was then added to the reaction
mixture, which was gradually warmed to room temperature and
diluted with CH2Cl2. The CH2Cl2 solution was washed with
water and brine, dried, and concentrated to leave the crude
aldehyde. The crude aldehyde was used directly for the next
reaction. To a suspension of NaH (60% NaH in oil, 1.01 g, 50.4
mmol) in THF (100 mL) was added at 0 °C a solution of ethyl
1
cm-1; H NMR δ 4.25 (m, 2H), 3.62 (t, 2H, J ) 6.3 Hz), 2.25-
2.23 (m, 2H), 1.63-1.56 (m, 4H), 0.89 (s, 9H), 0.05 (s, 6H); 13C
NMR δ 86.22, 78.53, 62.63, 51.27, 31.86, 25.91, 25.00, 18.51,
18.30, -5.34; FABMS m/z 243 (M+ + 1, 6.3). FABHRMS calcd
for C13H27O2Si 243.1780, found 243.1767.
(3Z)-8-(ter t-Bu tyld im eth ylsiloxy)-3-octen -1-yn e [(Z)-6]. A
solution of 10 (840 mg, 3.46 mmol) in MeOH (35.0 mL) was

6764 J . Org. Chem., Vol. 65, No. 20, 2000
Notes
hydrogenated for 15 h under hydrogen atmosphere in the
presence of Pd-CaCO3 (84.0 mg). The catalyst was filtered off,
and the filtrate was concentrated to dryness. The crude (Z)-olefin
derivative was successively exposed to Swern oxidation, dibro-
moolefination, and base treatment conditions as described for
preparation of (E)-6 to afford (Z)-6 (545 mg, 66%) as a colorless
was stirred at room temperature for 18 h and filtered. The
filtrate was washed with saturated aqueous Na2SO3, water, and
brine, dried, and concentrated to dryness. Chromatography of
the residue with hexane-AcOEt (7:1) gave trans-8a (287 mg,
53%; trans:cis ) 91:9) as a pale oil: IR 3620, 3448, 2179 cm-1
;
selected data for 1H NMR δ 3.66 (t, 2H, J ) 6.4 Hz), 3.10 (m,
2H), 1.66-1.59 (m, 2H), 1.58-1.51 (m, 4H), 0.17 (s, 9H); 13C
NMR δ 101.82, 89.29, 62.54, 60.61, 45.43, 32.22, 31.41, 21.96,
-0.34; MS m/z 212 (M+, 1.6). HRMS calcd for C11H20O2Si
212.1233, found 212.1234.
1
oil: IR 3306, 2097 cm-1; H NMR δ 6.00 (dt, 1H, J ) 10.7, 7.3
Hz), 5.46 (dd, 1H, J ) 10.7, 2.0 Hz), 3.62 (t, 2H, J ) 6.4 Hz),
3.07 (d, 1H, J ) 2.0 Hz), 2.35 (q, 2H, J ) 7.3 Hz), 1.58-1.53 (m,
2H), 1.50-1.44 (m, 2H), 0.89 (s, 9H), 0.05 (s, 6H); 13C NMR δ
145.95, 108.19, 81.24, 80.50, 62.86, 32.26, 29.94, 25.97, 24.98,
18.35, -5.28; MS m/z 238 (M+, 0.6). Anal. Calcd for C14H26OSi:
C, 70.52; H, 10.99. Found: C, 70.13; H, 11.18.
(5R*,6S*)-5,6-Ep oxy-8-p h en yloct-7-yn -1-ol (tr a n s-8b). Ac-
cording to the procedure described for the preparation of trans-
8a , (E)-7b (200 mg, 0.64 mmol) was treated with mCPBA to give
the epoxy derivative. To a solution of thus-prepared epoxy
derivative in THF (6.40 mL) was added a solution of TBAF (1.0
M THF solution, 0.70 mL, 0.70 mmol) at room temperature. The
reaction mixture was stirred for 1 h and diluted with Et2O, which
was washed with water and brined, dried, and concentrated to
dryness. Chromatography of the residue with hexane-AcOEt
(3:1) gave trans-8b (34.3 mg, 25%; trans:cis ) 81:19) as a pale
yellow oil: IR 3622, 3447, 2226 cm-1; selected data for 1H NMR
δ 7.44 (dd, 2H, J ) 7.3, 2.0 Hz), 7.34-7.29 (m, 3H), 3.68 (t, 2H,
J ) 5.9 Hz), 3.33 (d, 1H, J ) 2.0 Hz), 3.20 (td, 1H, J ) 5.9, 2.0
Hz), 1.83 (m, 1H), 1.72-1.56 (m, 5H); 13C NMR δ 131.81, 128.68,
128.27, 121.98, 85.70, 83.52, 62.52, 60.76, 45.73, 32.20, 31.45,
21.96; MS m/z 216 (M+, 6.7). HRMS calcd for C14H16O2 216.1150,
found 216.1151.
(5E)-8-Tr im eth ylsilyl-5-octen -7-yn -1-ol [(E)-7a ]. To a solu-
tion of (E)-6 (50.0 mg, 0.21 mmol) in THF (2.10 mL) was added
n-BuLi in hexane (1.46 M, 0.17 mL, 0.25 mmol) at -78 °C. After
stirring for 1 h, a solution of TMSCl (0.08 mL, 0.63 mmol) in
THF (0.50 mL) was added to the reaction mixture, which was
stirred at the same temperature for 30 min and then at room
temperature for 12 h. The reaction mixture was quenched by
addition of water and extracted with Et2O. The extract was
washed with water and brine, dried, and concentrated to
dryness. The residue was taken up in EtOH (2.00 mL) to which
10% HCl solution (0.20 mL) was added at room temperature.
The reaction mixture was stirred for 1 h, and EtOH was
evaporated off to leave the residue which was diluted with water
and extracted with AcOEt. The extract was washed with water
and brine, dried, and concentrated to dryness. Chromatography
of the residue with hexane-AcOEt (4:1) gave (E)-7a (27.6 mg,
(5R*,6S*)-5,6-Ep oxy-7-octyn e-1-ol (tr a n s-8c). According to
the procedure described for the preparation of trans-8b, trans-
8c (32.5 mg, 28%; trans:cis ) 95:5) was obtained from (E)-6 (200
1
67%) as a pale yellow oil: IR 3624, 3449 cm-1; H NMR δ 6.20
(dt, 1H, J ) 16.1, 7.3 Hz), 5.51 (dt, 1H, J ) 16.1, 1.5 Hz), 3.63
(t, 2H, J ) 6.4 Hz), 2.13 (qd, 2H, J ) 7.3, 1.5 Hz), 1.54 (quin,
2H, J ) 6.4 Hz), 1.50-1.44 (m, 2H), 0.18 (s, 9H); 13C NMR δ
145.61, 110.01, 103.97, 92.74, 62.61, 32.71, 32.06, 24.75, -0.07;
MS m/z 196 (M+, 17). HRMS calcd for C11H20OSi 196.1283, found
196.1281.
mg, 0.84 mmol) as pale yellow oil: IR 3622, 3472, 3307 cm-1
;
selected data for 1H NMR δ 3.67 (t, 2H, J ) 6.4 Hz), 3.11 (m,
2H), 2.31 (d, 1H, J ) 1.5 Hz), 1.66-1.53 (m, 6H); 13C NMR δ
80.29, 71.84, 62.27, 60.15, 44.75, 32.06, 31.22, 21.82; MS m/z
140 (M+, 7.0). HRMS calcd for C8H12O2 140.0837, found 140.0835.
(3R*,4S*)-3,4-Epoxy-8-tr im eth ysiloxy-1-tr im eth ylsilyloct-
1-yn e (tr a n s-9a ). A solution of trans-8a (100 mg, 0.47 mmol)
and TMS-imidazole (0.10 mL, 0.71 mmol) was stirred for 30 min
at room temperature and diluted with hexane. The resulting
precipitates were filtered off, and the filtrate was concentrated
to dryness. chromatography of the residue on silica gel (treated
with hexane-AcOEt containing 3% Et3N prior to use) with
hexane-AcOEt (20:1) afforded trans-9a (103 mg, 77%; trans:
cis ) 91:9) as a pale yellow oil: IR 2179 cm-1; selected data for
1H NMR δ 3.58 (t, 2H, J ) 6.4 Hz), 3.09 (m, 2H), 1.60-1.47 (m,
6H), 0.17 (s, 9H), 0.11 (s, 9H); 13C NMR δ 101.94, 89.15, 62.21,
60.65, 45.45, 32.26, 31.50, 22.01, -0.34, -0.52; MS m/z 284 (M+,
6.0). HRMS calcd for C14H28O2Si2 284.1628, found 284.1631.
(3R *,4S *)-3,4-E p oxy-8-t r im e t h ysiloxy-1-p h e n yloct -1-
yn e (tr a n s-9b). According to the procedure described for the
preparation of trans-9a , trans-9b (132 mg, 52%; trans:cis ) 83:
17) was obtained from trans-8b (195 mg, 0.90 mmol) as a pale
yellow oil: IR 2227 cm-1; selected data for 1H NMR δ 7.45-
7.43 (m, 2H), 7.33-7.28 (m, 3H), 3.60 (t, 2H, J ) 5.9 Hz), 3.26
(d, 1H, J ) 2.4 Hz), 3.19 (td, 1H, J ) 5.4, 2.4 Hz), 1.66-1.52 (m,
6H), 0.12 (s, 9H); 13C NMR δ 131.77, 128.61, 128.21, 122.01,
85.82, 83.38, 62.16, 60.74, 45.66, 32.22, 31.52, 22.00, -0.57; MS
m/z 288 (M+, 12). Anal. Calcd for C17H24O2Si: C, 70.79; H, 8.39.
Found: C, 70.93; H, 8.41.
(5Z)-8-Tr im eth ylsilyl-5-octen -7-yn -1-ol [(Z)-7a ]. According
to the procedure described for the preparation of (E)-7a , (Z)-7a
(22.1 mg, 56%) was obtained from (Z)-6 (48.3 mg, 0.20 mmol) as
1
a pale yellow oil: IR 3619, 2146 cm-1; H NMR δ 5.94 (dt, 1H,
J ) 10.7, 7.3 Hz), 5.50 (dt, 1H, J ) 10.7, 1.5 Hz), 3.67 (t, 2H, J
) 6.4 Hz), 2.36 (qd, 2H, J ) 7.3, 1.5 Hz), 1.64-1.58 (m, 2H),
1.54-1.48 (m, 2H), 0.19 (s, 9H); 13C NMR δ 144.87, 109.56,
102.00, 98.67, 62.55, 32.04, 29.83, 24.78, -0.07; MS m/z 196 (M+,
22). HRMS calcd for C11H20OSi 196.1283, found 196.1276.
(3E)-8-(ter t-Bu t yld im et h ylsiloxy)-1-p h en yl-3-oct en -1-
yn e [(E)-7b]. To a solution of (E)-6 (50.0 mg, 0.21 mmol) and
iodobenzene (0.04 mL, 0.31 mmol) in THF (0.50 mL) were
successively added Pd(PPh3)2Cl2 (4.40 mg, 0.60 × 10-2 mmol),
CuI (5.30 mg, 0.13 × 10-1 mmol), and diisopropylamine (1.60
mL) at room temperature. The reaction mixture was stirred for
1 h, and the precipitates were filtered off. The filtrate was
concentrated to leave a residual oil, which was chromatographed
with hexane-AcOEt (50:1) to afford (E)-7b (63.2 mg, 96%) as a
pale yellow oil: IR 2201 cm-1 1H NMR δ 7.42-7.40 (m, 2H),
;
7.32-7.27 (m, 3H), 6.24 (dt, 1H, J ) 15.6, 7.3 Hz), 5.70 (dt, 1H,
J ) 15.6, 1.5 Hz), 3.62 (t, 2H, J ) 6.3 Hz), 2.19 (qd, 2H, J ) 7.3,
1.5 Hz), 1.57-1.53 (m, 2H), 1.52-1.47 (m, 2H), 0.90 (s, 9H), 0.05
(s, 6H); 13C NMR δ 144.92, 131.41, 128.23, 127.85, 123.61,
109.69, 88.29, 87.93, 62.86, 32.98, 32.22, 25.97, 25.07, 18.35,
-5.30; MS m/z 314 (M+, 1.3). Anal. Calcd for C20H30OSi: C,
76.37; H, 9.61. Found: C, 76.09; H, 9.83.
(3R*,4S*)-3,4-E p oxy-8-t r im et h ysiloxyoct -1-yn e (tr a n s-
9c). According to the procedure described for the preparation of
trans-9a , trans-9c (126 mg, 84%; trans:cis ) 93:7) was obtained
from trans-8c (100 mg, 0.71 mmol) as a pale yellow oil: IR 3307,
2120 cm-1; selected data for 1H NMR δ 3.58 (t, 2H, J ) 6.4 Hz),
3.10 (m, 2H), 2.30 (d, 1H, J ) 1.5 Hz), 1.61-1.48 (m, 6H), 0.11
(s, 9H); 13C NMR δ 80.49, 71.70, 62.14, 60.18, 44.76, 32.19, 31.38,
21.96, -0.56; FABMS m/z 213 (M+ + 1, 4.5). Anal. Calcd for
(3Z)-8-(ter t-Bu t yld im et h ylsiloxy)-1-p h en yl-3-oct en -1-
yn e [(Z)-7b]. According to the procedure described for the
preparation of (E)-7b, (Z)-7b (111 mg, 84%) was obtained from
(Z)-6 (100 mg, 0.42 mmol) as a pale yellow oil: IR 2201 cm-1
;
1H NMR δ 7.44-7.42 (m, 2H), 7.32-7.29 (m, 3H), 5.97 (dt, 1H,
J ) 10.7, 7.3 Hz), 5.69 (dt, 1H, J ) 10.7, 1.5 Hz), 3.64 (t, 2H, J
) 6.4 Hz), 2.42 (qd, 2H, J ) 7.3, 1.5 Hz), 1.62-1.48 (m, 4H),
0.89 (s, 9H), 0.04 (s, 6H); 13C NMR δ 144.01, 131.38, 128.25,
127.94, 123.67, 109.22, 93.48, 86.40, 62.93, 32.33, 30.07, 25.95,
C
11H20O2Si: C, 62.21; H, 9.49. Found: C, 61.88; H, 9.55.
(3R*,4R*)-3,4-Epoxy-8-tr im eth ysiloxy-1-tr im eth ylsilyloct-
1-yn e (cis-9a ). According to the procedure described for conver-
sion of (E)-7a to trans-9a , cis-9a (177 mg, 25%) was obtained
from (Z)-7a (500 mg, 2.53 mmol) as a pale yellow oil: IR 2176
25.11, 18.35, -5.30; MS m/z 314 (M+, 3.4). Anal. Calcd for C20H30
OSi: C, 76.37; H, 9.61. Found: C, 76.10; H, 9.91.
-
1
cm-1; H NMR δ 3.61 (t, 2H, J ) 6.4 Hz), 3.42 (d, 1H, J ) 3.9
(5R*,6S*)-5,6-Ep oxy-8-tr im eth ylsilyloct-7-yn -1-ol (tr a n s-
8a ). To a solution of (E)-7a (500 mg, 2.53 mmol) in CH2Cl2 (25.0
mL) were added Na2HPO4 (3.60 g, 25.5 mmol) and mCPBA (80%
purity, 1.65 g, 7.70 mmol) at room temperature. The suspension
Hz), 3.02 (td, 1H, J ) 6.4, 3.9 Hz), 1.79-1.50 (m, 6H), 0.18 (s,
9H), 0.11 (s, 9H); 13C NMR δ 100.41, 91.03, 62.30, 58.10, 45.20,
32.42, 29.04, 22.21, -0.32, -0.52; MS m/z 284 (M+, 7.0). HRMS
calcd for C14H28O2Si2 284.1628, found 284.1631.

Notes
(3R *,4R *)-3,4-E p oxy-8-t r im e t h ysiloxy-1-p h e n yloct -1-
J . Org. Chem., Vol. 65, No. 20, 2000 6765
(dt, 1H, J ) 12.7, 4.4 Hz), 3.89 (m, 1H), 3.73 (m, 1H), 2.14-2.09
(m, 2H), 1.89-1.70 (m, 5H); 13C NMR δ 199.68, 137.95, 129.83,
128.90, 127.71, 98.15, 91.09, 85.43, 71.84, 67.96, 36.41, 30.95,
20.70; MS m/z 474 (M+ - CO, 21). Anal. Calcd for C20H16Co2O8:
C, 47.83; H, 3.21. Found: C, 48.12; H, 3.22.
yn e (cis-9b). According to the procedure described for conversion
of (E)-7b to trans-9b, cis-9b (23.9 mg, 29%; cis:trans ) 93:7) was
obtained from (Z)-7b (90.0 mg, 0.29 mmol) as a pale yellow oil:
IR 2230 cm-1; selected data for 1H NMR δ 7.44 (dd, 2H, J ) 7.3,
1.5 Hz), 7.33-7.29 (m, 3H), 3.65 (d, 1H, J ) 3.9 Hz), 3.62 (t,
2H, J ) 6.4 Hz), 3.14 (td, 1H, J ) 5.9, 3.9 Hz), 1.87-1.74 (m,
2H), 1.68-1.56 (m, 4H), 0.10 (s, 9H); 13C NMR δ 131.88, 128.70,
128.30, 122.16, 85.25, 84.22, 62.32, 58.46, 45.59, 32.40, 29.26,
22.36, -0.50; MS m/z 288 (M+, 20). Anal. Calcd for C17H24O2Si:
C, 70.79; H, 8.39. Found: C, 70.51; H, 8.42.
H exa ca r b on yl-µ-[η4-(2R*,3S*)-3-h yd r oxy-2-et h yn yl-ox-
ep a n e]d icob a lt (Co-Co) (cis-11c). A reddish brown oil: IR
3580, 2095, 2056, 2029 cm-1 1H NMR δ 6.07 (s, 1H), 4.55 (s,
;
1H), 3.92 (dt, 1H, J ) 10.3, 3.4 Hz), 3.85-3.82 (m, 2H), 2.61 (d,
1H, J ) 10.3 Hz, OH), 2.04-1.93 (m, 2H), 1.77-1.57 (m, 4H);
13C NMR δ 199.61, 94.02, 79.73, 73.21, 72.24, 68.88, 37.34, 29.65,
19.23; FABMS m/z 427 (M+ + 1, 4.4). Anal. Calcd for C14H12
-
(3R*,4R*)-3,4-Ep oxy-8-tr im eth ysiloxyoct-1-yn e (cis-9c).
According to the procedure described for conversion of (E)-6 to
trans-9c, cis-9c (28.6 mg, 75%; cis:trans ) 93:7) was obtained
from (Z)-6 (24.6 mg, 0.18 mmol) as a pale yellow oil: IR 3307,
2124 cm-1; selected data for 1H NMR δ 3.60 (t, 2H, J ) 6.4 Hz),
3.42 (dd, 1H, J ) 3.9, 2.0 Hz), 3.04 (td, 1H, J ) 6.4, 3.9 Hz),
2.34 (d, 1H, J ) 2.0 Hz), 1.79-1.67 (m, 2H), 1.65-1.53 (m, 4H),
0.11 (s, 9H); 13C NMR δ 78.89, 73.59, 62.27, 57.76, 44.69, 32.31,
28.97, 22.27, -0.52; CIMS m/z 213 (M+ + 1, 100). Anal. Calcd
for C11H20O2Si: C, 62.21; H, 9.49. Found: C, 61.91; H, 9.63.
Gen er a l P r oced u r e for Co2(CO)8-Med ia ted En d o Mod e
Rin g Closu r e. To a solution of the epoxide 8, 9 (1.00 mmol) in
CH2Cl2 (30.0 mL) was added Co2(CO)8 (1.10 mmol) at room
temperature. After being stirred for 20-30 min (consumption
of the starting material was monitored by TLC), the reaction
mixture was cooled to -78 °C and held at the same temperature
for 30 min. A solution of BF3‚OEt2 in CH2Cl2 (1.0 M solution;
3.00 mmol) was added to the reaction mixture, which was further
stirred at -78 °C for 30 min. The reaction was quenched by
addition of water and gradually warmed to room temperature.
The CH2Cl2 layer was separated, washed with water and brine,
dried, and concentrated to dryness. Chromatography with
hexane-AcOEt (20:1) afforded 11. Chemical yields and ratio
between trans and cis isomers are summarized in Table 1.
Hexa ca r bon yl-µ-[η4-(2R*,3S*)-3-h yd r oxy-2-(2-tr im eth yl-
sily)eth yn yloxep a n e]d icoba lt(Co-Co) (cis-11a ). A reddish
Co2O8: C, 39.46; H, 2.84. Found: C, 39.09; H, 3.16.
H exa ca r b on yl-µ-[η4-(2R*,3R*)-3-h yd r oxy-2-et h yn yl-ox-
ep a n e]d icoba lt(Co-Co) (tr a n s-11c). A reddish brown oil: IR
3580, 2095, 2054, 2031 cm-1 1H NMR δ 6.08 (s, 1H), 4.30 (d,
;
1H, J ) 8.3 Hz), 4.03 (m, 1H), 3.70 (m, 1H), 3.61 (m, 1H), 2.10
(m, 1H), 1.85-1.63 (m, 5H); 13C NMR δ 199.84, 96.03, 84.85,
71.66, 70.51, 65.84, 36.48, 30.50, 20.85; FABMS m/z 427 (M+
1, 1.9). Anal. Calcd for C14H12Co2O8: C, 39.46; H, 2.84. Found:
C, 39.15; H, 3.00.
+
Dir ect Rin g op en in g of tr a n s-8c a n d cis-8c. A solution of
BF3‚OEt2 in CH2Cl2 (0.10 M solution; 0.14 mL, 0.14 × 10-1
mmol) was added to a solution of trans-8c (20.0 mg, 0.14 mmol)
in CH2Cl2 (4.80 mL) at -78 °C. The reaction mixture was stirred
at the same temperature for 10 min, gradually warmed to 0 °C,
and then quenched by addition of water. The CH2Cl2 layer was
separated, washed with brine, dried, and concentrated to dry-
ness. The residue was dissolved in CH2Cl2 (4.00 mL) to which
Ac2O (21.5 mg, 0.21 mmol) and Et3N (21.3 mg, 0.21 mmol) were
added. The reaction mixture was allowed to stand for 1 h, diluted
with CH2Cl2, which was washed with water and brine, dried,
and concentrated to dryness. Chromatography of the residue
with hexane-AcOEt (10:1) afforded (1′R*,2S*)-2-(1′-acetoxy-2′-
propyn-1′-yl)tetrahydropyrane (15; 18.0 mg, 71%) and (2*R,3S*)-
3-acetoxy-2-ethynyloxepane (16; 1.20 mg, 5%). Compound 15 was
a pale yellow oil: IR 3307, 2128, 1740 cm-1 1H NMR δ 5.37
;
1
brown oil: IR 3605, 2089, 2050, 2022 cm-1; H NMR δ 4.56 (s,
(dd, 1H, J ) 3.4, 2.4 Hz), 4.08 (m, 1H), 3.53 (m, 1H), 3.47 (td,
1H, J ) 11.2, 2.0 Hz), 2.33 (d, 1H, J ) 2.4 Hz), 2.13 (s, 3H), 1.91
(m, 1H), 1.70-1.50 (m, 5H); 13C NMR δ 169.86, 78.46, 77.90,
74.54, 68.81, 66.25, 26.65, 25.55, 22.88, 20.95; CIMS m/z 183
(M+ + 1, 100). Anal. Calcd for C10H14O3: C, 65.92; H, 7.74.
Found: C, 65.73; H, 7.98. Compound 16 was a colorless oil: IR
3306, 2124, 1733 cm-1; 1H NMR δ 5.08 (td, 1H, J ) 6.6, 3.3 Hz),
4.36 (dd, 1H, J ) 6.6, 2.3 Hz), 3.98 (m, 1H), 3.70 (m, 1H), 2.48
(d, 1H, J ) 2.3 Hz), 2.08 (s, 3H), 1.96-1.59 (m, 6H); 13C NMR δ
169.95, 81.13, 74.32, 71.74, 68.61, 30.91, 30.17, 21.33, 21.17; MS
m/z 182 (M+, 1.1). HRMS calcd for C10H14O3 182.0942, found
182.0939. Similar treatment of cis-8c (20.0 mg, 0.14 mmol) gave
(1′R*,2R*)-2-(1′-acetoxy-2′-propyn-1′-yl)tetrahydropyran (17; 20.9
1H), 3.95 (dt, 1H, J ) 10.7, 3.4 Hz), 3.90-3.79 (m, 2H), 2.67 (d,
1H, J ) 10.3 Hz, OH), 2.04-1.93 (m, 2H), 1.77-1.68 (m, 2H),
1.60-1.54 (m, 2H), 0.31 (s, 9H); 13C NMR δ 200.27, 109.20, 79.89,
78.65, 73.21, 68.70, 37.52, 29.56, 19.18, 0.76; MS m/z 470 (M+
CO, 10). Anal. Calcd for C17H20Co2O8Si: C, 40.98; H, 4.05.
Found: C, 40.83; H, 4.02.
-
Hexa ca r bon yl-µ-[η4-(2R*,3R*)-3-h yd r oxy-2-(2-tr im eth yl-
silyl)eth yn yloxep a n e]d icoba lt(Co-Co) (tr a n s-11a ). A red-
dish brown oil: IR 3600, 2087, 2048, 2009 cm-1; 1H NMR δ 4.30
(d, 1H, J ) 7.8 Hz), 4.07 (dt, 1H, J ) 12.2, 4.9 Hz), 3.72-3.64
(m, 2H), 2.09 (m, 1H), 1.84-1.66 (m, 5H), 1.46 (d, 1H, J ) 4.4
Hz, OH), 0.31 (s, 9H); 13C NMR δ 200.59, 128.32, 111.43, 85.61,
78.71, 71.32, 36.64, 30.78, 20.78, 0.69; MS m/z 470 (M+ - CO,
11). Anal. Calcd for C17H20Co2O8Si: C, 40.98; H, 4.05. Found:
C, 40.98; H, 4.06.
mg, 82%) as a pale yellow oil: IR 3307, 2128, 1741 cm-1 1H
;
NMR δ 5.38 (dd, 1H, J ) 6.4, 2.4 Hz), 4.04 (m, 1H), 3.51 (ddd,
1H, J ) 10.8, 6.4, 2.0 Hz), 3.44 (td, 1H, J ) 11.2, 2.0 Hz), 2.48
(d, 1H, J ) 2.4 Hz), 2.13 (s, 3H), 1.92 (m, 1H), 1.80 (m, 1H),
1.62-1.41 (m, 4H); 13C NMR δ 169.78, 78.71, 77.56, 74.68, 68.64,
66.06, 27.10, 25.54, 22.75, 20.95; CIMS m/z 183 (M+ + 1, 100).
Anal. Calcd for C10H14O3: C, 65.92; H, 7.74. Found: C, 65.40;
H, 7.85.
H exa ca r b on yl-µ-[η4-(2R*,3S*)-3-h yd r oxy-2-(2-p h en yl)-
eth yn yloxep a n e]d icoba lt(Co-Co) (cis-11b). A reddish brown
oil: IR 3580, 2092, 2055, 2027 cm-1; 1H NMR δ 7.55 (dd, 2H, J
) 6.8, 1.5 Hz), 7.36-7.28 (m, 3H), 4.77 (s, 1H), 4.11 (dt, 1H, J )
10.7, 3.4 Hz), 3.98-3.89 (m, 2H), 2.67 (d, 1H, J ) 10.3 Hz, OH),
2.07-1.98 (m, 2H), 1.83-1.62 (m, 4H); 13C NMR δ 199.42,
138.06, 129.58, 128.77, 127.60, 95.78, 91.12, 79.80, 72.89, 69.04,
37.49, 29.72, 19.32; MS m/z 474 (M+ - CO, 21). Anal. Calcd for
Su p p or tin g In for m a tion Ava ila ble: Spectral data of
compound 12 and 13, 1H and 13C NMR spectra for compounds
(E)-6, (E)-7a , (Z)-7a , trans-8a ,b,c, trans-9a , cis-9a , 10, 12, 13,
and 16,1H NMR spectra for compounds 11. This material is
available free of charge via the Internet at http://pubs.acs.org.
C
20H16Co2O8: C, 47.83; H, 3.21. Found: C, 47.77; H, 3.19.
H exa ca r b on yl-µ-[η4-(2R*,3R*)-3-h yd r oxy-2-(2-p h en yl)-
eth yn yloxep a n e]d icoba lt(Co-Co) (tr a n s-11b). A reddish
brown oil: IR 3580, 2091, 2054, 2028 cm-1
;
1H NMR δ 7.63-
7.61 (m, 2H), 7.35-7.28 (m, 3H), 4.56 (d, 1H, J ) 7.3 Hz), 4.15
J O000450+