Ruthenium carbene complexes with imidazol-2-ylidene ligands: Syntheses of conduritol derivatives reveals superior RCM activity

Article abstract of DOI:10.1016/S0040-4020(99)01102-3

Syntheses of conduritol A, E and F derivatives are described using galactitol, D-mannitol and D-glucitol, respectively, as the starting materials. The key steps of this approach comprise a Tebbe olefination reaction for the preparation of dienes 15, 21 and 27 followed by ring closing metathesis (RCM) for the formation of the polyhydroxylated cyclohexene rings of the targets. A comparative study shows that the latter transformation is best achieved with catalytic amounts of ruthenium carbene complex 3a bearing one PCy₃ and one 2,3-dihydro-1H-imidazol-2-ylidene ligand in its coordination sphere. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(99)01102-3

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 2195±2202
Ruthenium Carbene Complexes with Imidazol-2-ylidene Ligands:
Syntheses of Conduritol Derivatives Reveals
Superior RCM Activity
*
È
Lutz Ackermann, David El Tom and Alois Furstner
È È
Max-Planck-Institut fur Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mulheim/Ruhr, Germany
Accepted 7 December 1999
AbstractÐSyntheses of conduritol A, E and F derivatives are described using galactitol, d-mannitol and d-glucitol, respectively, as the
starting materials. The key steps of this approach comprise a Tebbe ole®nation reaction for the preparation of dienes 15, 21 and 27 followed
by ring closing metathesis (RCM) for the formation of the polyhydroxylated cyclohexene rings of the targets. A comparative study shows that
the latter transformation is best achieved with catalytic amounts of ruthenium carbene complex 3a bearing one PCy3 and one 2,3-dihydro-1H-
imidazol-2-ylidene ligand in its coordination sphere. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
independently reported by three different research
groups,7±9 these new reagents allow the formation of tri-
and tetra-substituted cycloalkenes which are beyond the
scope of 2 and have so far been a domain of the molyb-
denum complex 1. In terms of stability, however,
compounds 3 turned out to be even more robust than the
original Grubbs carbene 2 in solution as well as in the solid
state. These favorable properties in combination with the
user-friendly character of 3 and its excellent tolerance
toward an array of polar groups sum up to a very attractive
overall application pro®le. The synthesis of three members
of the conduritol family of natural products summarized
Ring closing metathesis (RCM) is a very powerful method
for the formation of unsaturated cyclic systems from acyclic
dienes.1 According to the generally accepted mechanism,2
the reaction proceeds via a sequence of formal [212]
cycloadditions/cycloreversions and is mainly driven by
entropy gained by release of ethylene or other volatile
side products (Scheme 1). Among the plethora of metathesis
pre-catalysts described in the literature, the molybdenum
alkylidene species 13 developed by Schrock and the ruthe-
nium carbene complex 24 introduced by Grubbs play a most
prominent role and set the standards in the ®eld (Scheme 2).
Whereas the former is distinguished by its superior reac-
tivity even toward highly substituted alkenes, the latter
turned out to be somewhat less active but signi®cantly
more stable, is easy to handle, shows an excellent compati-
bility with functional groups, and has therefore gained great
popularity over the last few years.1 This analysis makes
clear that a reagent combining the positive features of either
system into a single RCM catalyst is highly desirable and
will strongly impact further advancements in this timely
®eld of research.
A promising development in this direction has recently been
triggered by the advent of complexes of the general type 3
containing a mixed ligand sphere with one phosphine and
one bulky N,N0-disubstituted 2,3-dihydro-1H-imidazol-2-
ylidene substituent (Rˆmesityl, cyclohexyl, isopropyl
etc.)5,6 at the ruthenium carbene center. As has been
Keywords: ruthenium carbene complex; ole®nation; metathesis.
* Corresponding author. E-mail: fuerstner@mpi-muelheim.mpg.de
Scheme 1.
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(99)01102-3

2196
L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
Scheme 2.
below provided an unexpected but excellent opportunity to
substantiate this preliminary assessment.
one of the key steps,11 we now wish to disclose our comple-
mentary approach to conduritols A, E and F which
exempli®es the superb activity of the new ruthenium
based metathesis catalyst 3a (Rˆ2,4,6-trimethylphenyl)
(Scheme 3).
Results and Discussion
Retrosynthetic analysis of the targets shows that
(2)-conduritol F (9) exhibits the same stereochemistry as
d-glucose, (2)-conduritol E (8) shows the pattern of
d-mannose, whereas conduritol A (4) as a meso compound
can be matched by galactose. For a matter of convenience,
our synthesis of compound 9 starts from cheap and commer-
cially available d-glucitol 10 (Scheme 4). Reaction with
p-methoxyphenyldiphenylmethyl chloride (p-methoxytrityl
chloride, p-MeOTrCl)12 in the presence of pyridine and
DMAP results in the protection of both primary hydroxyl
groups in good yield. Benzylation of the remaining second-
ary alcohol functions of 11 thus obtained followed by
cleavage of the pMeOTr ethers in the resulting product 12
with H2SO4 cat. in MeOH/CH2Cl2 readily delivers the corre-
sponding diol 13. Swern oxidation was found to be the
Preparation of the diene substrates
Polyhydroxylated cyclohexene derivatives in general
exhibit diverse biological effects and have repeatedly been
used as starting materials for advanced organic synthesis.10
As a result, conduritols A±F (4±9) and derivatives thereof
have attracted considerable attention and were frequently
targeted in recent years. Despite the fact that various
successful approaches to products of this type have already
been reported in the literature,10 RCM constitutes an
obvious tool for their synthesis since the required diene
substrates can be easily traced back to cheap mono-
saccharide building blocks. Prompted by a recent publi-
cation of d'Alarcao et al. describing the conversion of
d-xylose into protected conduritol B and F via RCM as
Scheme 3.
Scheme 4. [a] p-methoxytrityl chloride, DMAP, pyridine, rt, 85%; [b] BnBr, NaH, THF, rt, 96%; [c] H2SO4 cat., MeOH/CH2Cl2, 08C, 87%; [d] DMSO, oxalyl
chloride, NEt3, CH2Cl2, 2788C!rt, quant.; [e] Cp2Ti(m-Cl)(m-CH2)AlMe2, THF/pyridine, 2408C!rt, 42%.

L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
2197
Scheme 5. [a] p-methoxytrityl chloride, DMAP, pyridine, 78% (16!17), 74% (22!23); [b] BnBr, NaH, THF, rt, 92% (17!18); 91% (23!24); [c] H2SO4 cat.,
MeOH/CH2Cl2, 08C, 94% (18!19); 89% (24!25); [d] DMSO, oxalyl chloride, NEt3, CH2Cl2, 2788C!rt, quant.; [e] Cp2Ti(m-Cl)(m-CH2)AlMe2, THF/
pyridine, 2408C!rt, 47% (20!21), 42% (26!27).
method of choice for the preparation of dialdehyde 14,13
whereas attempted oxidation of 13 with Pr4NRuO4 or
i.e. the conversion of dienes 15, 21, 27, 29 and 30 into the
protected conduritol derivatives 31±35 by means of RCM,
turned out to be signi®cantly more challenging than antici-
pated. The high reactivity of the Grubbs benzylidenecarbene
2 toward terminal alkenes in general,1 the kinetically
favorable formation of a six-membered ring, and ample
precedence for the successful application of 2 in the carbo-
hydrate series21±23 suggested that the fully protected
terminal diene 15 would react without incident with this
particular catalyst. In contrast to our expectations, however,
this substrate cyclizes very reluctantly on exposure to
catalytic amounts of 2 (5 mol%) in re¯uxing CH2Cl2
solution.24 As little as 32% conversion (GC) into cyclo-
alkene 31 was noticed after 60 h (!) reaction time; complete
conversion can only be reached with unduely high catalyst
loadings ($30%). This poor result is in stark contrast to the
smooth cyclization of 15 using Schrock's molybdenum
complex 1 as pre-catalyst, which depletes the starting material
within 1 h and delivers compound 31 in excellent yield.
14
by means of the Dess±Martin periodinane15 failed to afford
this rather labile product which must be processed without
delay. Unfortunately, however, the sensitivity of 14 turned
out to be a major obstacle for the envisaged conversion into
diene 15. Despite considerable experimentation with Wittig
ole®nations (in the presence/absence of crown ethers),16
alkene syntheses using CH2Br2/Zn in the presence of
different Lewis acids,17 Cr(II)-induced Takai±Utimoto
ole®nation,18 and the Peterson reaction,19 the overall yield
remained low. Best results were obtained with the Tebbe
reagent20 by slowly adding a solution of Cp2Ti(m-Cl)-
(m-CH2)AlMe2 in toluene to a solution of the dialdehyde
in THF/pyridine. Under these conditions, the desired diene
15 was obtained in 42% yield.
Although this outcome for the seemingly trivial alkene
formation is far from optimal, the small number of steps
and the ready accessibility of all precursors in large quantity
from inexpensive starting materials encouraged us to extend
this approach to d-mannitol 16 and the meso compound 22
(galactitol) as well. Scheme 5 summarizes our results: in
analogy to the glucitol case described above, all transfor-
mations proceed smoothly except for the ole®nation; the
yields obtained in this dif®cult transformation are again in
the 40±50% range.
In view of the preliminary results summarized in the Intro-
duction indicating that the new ruthenium carbene species 3
bearing one imidazol-2-ylidene ligand rival the reactivity of
1,7±9 we were prompted to probe their performance in this
particular application as well. In fact, the reaction rate for
the cyclization of diene 15 on exposure to 3a (Rˆmesityl,
5 mol%)7 is in the same range as that observed with
We have also brie¯y pursued an alternative synthesis of a
suitable diene precursor for the preparation of conduritol E.
As can be seen from Scheme 6, reduction of (R,R)-dimethyl
tartrate 28 with Dibal-H followed by addition of vinyl-
magnesium bromide to the aldehyde formed in situ affords
the C2-symmetric diol 29 as the major isomer which can be
converted into diacetate 30 under standard conditions.
Comparative investigation of the reactivity of metathesis
catalysts 1±3
Scheme 6. [a] Dibal-H, toluene, 2788C; [b] vinylmagnesium bromide,
2788C; 41% (over both steps) (1ca. 20% of isomers); [c] Ac2O, CH2Cl2,
pyridine, re¯ux, 83%.
The envisaged key step of our approach to the conduritols,

2198
L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
Table 1. Comparative investigation of the reactivity of different metathesis pre-catalysts
Entry
Substrate
Catalyst
Mol%
t (h)
Product
Yield (%)a
1
2
3
2
5
5
5
60
1
2
32b
92
1
3a
89
4
5
1
3a
5
5
1
1
95
90
6
7
1
3a
5
5
1
3
91
85
8
9
10
1
2
3a
5
20
1.5
2
20
2
0
0c
69
11
12
2
3a
20
1
120
5
77
71
a Isolated yield unless stated otherwise.
b GC yield.
c Cyclohexene 34 was not obtained; the catalyst delivers only hydroxyketone 36 in 29% yield, cf. Scheme 7.
Schrock's catalyst, and the isolated yield of 31 is also
virtually identical in both cases. In view of the signi®-
cantly higher stability of 3a toward air and moisture,
however, this reagent has a clear-cut advantage in prac-
tical terms over the very sensitive molybdenum alky-
lidene 1 which can only be handled using rigorous
Schlenk techniques.
120 h to go to completion despite of the high catalyst
loading (20%). An additional illustration of the superior
activity of 3a was encountered when applied to the diol
derivative 29. It is the only catalyst which allows the trans-
formation of this particular substrate into the cyclohexene
derivative 34, since the molybdenum species 1 is incom-
patible with the unprotected ±OH groups, whereas catalyst
2 effects a slow isomerization of one of the double bonds
rather than RCM and thereby delivers hydroxyketone 36 as
the only product (Scheme 7).
The other data summarized in Table 1 concerning the cycli-
zation of the manno-con®gurated dienes 21, 29 and 30 as
well as the meso-diene 27 into the conduritol E and A
derivatives 32, 34, 35 and 33, respectively, fully support
this notion. Again, the reactivity of ruthenium carbene 2
was found to be signi®cantly lower than that of carbene
3a in all cases investigated. Particularly revealing is a
comparison of entries 11 and 12: Whereas substrate 30
cyclizes smoothly in the presence of as little as 1 mol% of
complex 3a in less than 5 h, the reaction mediated by 2 takes
It may therefore be concluded that the newly discovered
ruthenium species 3 bearing one imidazol-2-ylidene ligand
constitute excellent tools for RCM by combining the activ-
ity of the classical molybdenum systems with the stability
and tolerance of ruthenium based catalysts. Further studies
corroborating this aspect are underway and will be reported
in due course.25
Scheme 7. [a] 2 (20 mol%), CH2Cl2, re¯ux, 20 h, 29%; [b] 3a (1.5 mol%), CH2Cl2, re¯ux, 69%.

L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
2199
Experimental
Prepared as described above from galactitol 22 (1.00 g,
5.49 mmol). Colorless syrup (2.96 g, 74%). 1H NMR
(300 MHz, CD2Cl2) d 2.64 (2H, d, Jˆ5.7 Hz), 2.72 (2H,
m), 3.22 (2H, dd, Jˆ6.2, 9.7 Hz), 3.33 (2H, dd, Jˆ4.5,
9.6 Hz), 3.55 (2H, m), 3.78 (6H, s), 3.99 (2H, q,
Jˆ5.1 Hz), 6.84 (4H, dt, Jˆ8.9, 2.6 Hz), 7.28 (16H, m),
7.43 (8H, m); 13C NMR (75 MHz, CD2Cl2) d 55.6, 66.5,
69.7, 72.2, 87.2, 113.6, 127.4, 128.3, 128.6, 130.7, 135.5,
144.6, 144.7, 159.2; IR: 3447, 3057, 3033, 3002, 2932,
2836, 1608, 1584, 1510, 1491, 1463, 1447, 1413, 1385,
1300, 1251, 1224, 1180, 1155, 1115, 1074, 1033, 1001,
902, 832, 796, 766, 727, 707, 633, 587; MS (EI) m/z (rel.
intensity) 726 ([M1], 2), 273 (100), 165 (7), 44 (7).
General
All reactions were carried out under Ar in pre-dried glass-
ware using Schlenk techniques. The solvents were dried by
distillation over the drying agents indicated and were stored
and transferred under Ar: CH2Cl2 (P4O10), toluene (Na/K),
THF (magnesium/anthracene), pyridine (KOH), EtOH
(Mg), MeOH (Mg). Flash chromatography: Merck silica
gel (230±400 mesh) using hexane/EtOAc in various propor-
tions as eluent. Mp: Gallenkamp apparatus (uncorrected).
NMR: Spectra were recorded on a Bruker DPX 300 spectro-
meter in the solvent indicated. Chemical shifts (d) are given
in ppm relative to TMS, coupling constants (J) in Hz. The
multiplicity in the 13C NMR spectra refers to the geminal
protons (DEPT). IR: Nicolet FT-7199, wavenumbers in
cm21. MS: Finnigan MAT 8200 (70 eV); HRMS: Finnigan
MAT SSQ 7000 (70 eV). Elemental analyses: Dornis &
Kolbe, MuÈlheim. Commercially available reagents
(Aldrich, Fluka) were used as received. The solution of
the Tebbe reagent was purchased from Fluka.
2,3,4,5-Tetra-O-benzyl-1,6-bis[(p-methoxyphenyl)(diphe-
nyl)methyl]-d-glucitol (12). Compound 11 (3.00 g,
4.13 mmol) is added in portions to a cooled (08C) suspen-
sion of sodium hydride (1.58 g, 66.0 mmol) in THF
(50 mL). After the evolution of gas has ceased, benzyl bro-
mide (7.85 mL, 66.0 mmol) is added dropwise during 1 h at
the same temperature. After stirring for 16 h at room
temperature, the reaction is quenched by carefully adding
sat. aq. NH4Cl (50 mL) at 08C. The organic layer is washed
with water (2£30 mL) and brine (2£30 mL), dried (Na2SO4)
and concentrated. Flash chromatography (hexane/EtOAc,
1:0!10:1) affords product 12 as a colorless syrup (4.30 g,
96%). 1H NMR (300 MHz, CD2Cl2) d 3.28 (2H, dt, Jˆ5.5,
10.1 Hz), 3.42 (1H, dd, Jˆ2.8, 10.2 Hz), 3.56 (1H, dd,
Jˆ2.1, 10.3 Hz), 3.70 (3H, s), 3.71 (3H, s), 3.90 (3H, m),
4.06 (2H, m), 4.29 (1H, d, Jˆ11.1 Hz), 4.47 (1H, d,
Jˆ11.9 Hz), 4.51 (1H, d, Jˆ12.6 Hz) 4.60 (2H, d,
Jˆ11.3 Hz), 4.73 (1H, d, Jˆ11.5 Hz), 4.76 (1H, d,
Jˆ11.7 Hz), 6.70 (4H, dd, Jˆ2.2, 8.9 Hz), 6.76 (2H, m),
7.28 (42H, m); 13C NMR (75 MHz, CD2Cl2) d 55.5, 55.6,
63.3, 63.9, 72.5, 73.4, 73.9, 74.8, 78.7, 79.4, 79.8, 80.3,
86.6, 86.7, 113.3, 113.4, 127.1, 127.2, 127.5, 127.6, 127.8,
128.0, 128.1, 128.2, 128.3, 128.4, 128.5, 128.6, 128.7,
128.8, 128.9, 130.8, 135.8, 135.9, 138.8, 139.2, 139.3,
139.4, 145.1, 145.2, 158.9, 159.0; IR: 3086, 3060, 3030,
3002, 2931, 2876, 2835, 1607, 1584, 1510, 1495, 1448,
1393, 1350, 1301, 1252, 1218, 1180, 1154, 1087, 1070,
1031, 1002, 901, 832, 796, 735, 698, 631, 589; MS (EI)
m/z (rel. intensity) 1086 ([M1], ,0.1), 363 (8), 273 (100),
91 (40).
1,6-Bis[( p-methoxyphenyl)(diphenyl)methyl]-d-glucitol
(11). p-Methoxytrityl chloride (17.50 g, 56.7 mmol) is
added in portions to a cooled solution (08C) of d-(2)-gluci-
tol 10 (5.00 g, 27.4 mmol) and DMAP (1.60 g, 13.1 mmol)
in pyridine (100 mL) over a period of 2 h. The mixture is
stirred for 48 h at room temperature. After addition of
EtOAc (100 mL), the reaction mixture is washed with sat.
aq. NH4Cl (2£50 mL), water (50 mL) and brine (2£50 mL),
the combined organic layers are dried (Na2SO4) and concen-
trated. Flash chromatography (hexane/EtOAc, 10:1!2:1)
gives the title compound as a colorless syrup (17.0 g,
85%). 1H NMR (300 MHz, CD2Cl2) d 2.75 (1H, d,
Jˆ5.8 Hz), 2.94 (2H, m), 3.07 (1H, d, Jˆ5.5 Hz), 3.16
(1H, dd, Jˆ6.2, 9.6 Hz), 3.28 (3H, m), 3.61 (1H, t,
Jˆ5.9 Hz), 3.82 (9H, m), 6.80 (4H, d, Jˆ8.8 Hz), 7.25
(16H, m), 7.43 (8H, m); 13C NMR (75 MHz, CD2Cl2) d
55.6, 65.2, 65.3, 70.2, 71.9, 73.5, 73.9, 87.0, 113.5, 127.4,
128.3, 128.6, 130.7, 135.6, 135.6, 144.6, 144.7, 144.8,
159.2; IR: 3440, 3057, 3032, 3001, 2932, 2836, 1608,
1583, 1510, 1491, 1463, 1447, 1413, 1300, 1251, 1223,
1180, 1154, 1076, 1033, 1001, 989, 950, 902, 832, 796,
766, 755, 727, 707, 632, 590, 548; MS (EI) m/z (rel. inten-
sity): 726 ([M1], 2), 273 (100), 165 (7), 44 (7); HRMS
C46H46O8 calcd 726.3193, found 726.3204.
2,3,4,5-Tetra-O-benzyl-1,6-bis[(p-methoxyphenyl)(diphe-
nyl)methyl]-d-mannitol (18). Prepared as described above
from substrate 17 (6.00 g, 8.25 mmol). Colorless syrup
1
(8.23 g, 92%). H NMR (300 MHz, CD2Cl2) d 3.29 (2H,
1,6-Bis[( p-methoxyphenyl)(diphenyl)methyl]-d-manni-
tol (17). Prepared as described above from d-mannitol 16
(2.00 g, 10.98 mmol). Colorless syrup (6.25 g, 78%). H
dd, Jˆ4.2, 10.5 Hz), 3.70 (8H, m), 3.86 (2H, m), 4.25±
4.45 (8H, m), 4.79 (2H, d, Jˆ11.7 Hz), 6.69 (4H, dt,
Jˆ8.9, 2.5 Hz), 6.91 (4H, m), 7.18 (18H, m), 7.35 (10H,
m), 7.47 (12H, m); 13C NMR (75 MHz, CD2Cl2) d 55.5,
62.4, 71.9, 74.0, 77.9, 79.0, 86.7, 113.4, 127.2, 127.5,
127.6, 127.7, 127.9, 128.1, 128.2, 128.4, 128.7, 128.8,
128.9, 130.8, 135.9, 139.1, 139.2, 145.1, 145.2, 159.0; IR:
3060, 3031, 3004, 2931, 2878, 2835, 1607, 1584, 1510, 1496,
1448, 1392, 1325, 1302, 1252, 1219, 1180, 1092, 1071, 1031,
1002, 985, 901, 832, 735, 698, 632, 589; MS (EI) m/z (rel.
intensity) 1086 ([M1], ,0.1), 363 (14), 273 (100), 91 (61).
1
NMR (300 MHz, CD2Cl2) d 2.72 (2H, d, Jˆ5.3 Hz), 2.91
(2H, d, Jˆ6.2 Hz), 3.28 (4H, m), 3.75 (8H, m), 3.87 (2H,
quint., Jˆ5.6 Hz), 6.82 (4H, dt, Jˆ8.9, 2.5 Hz), 7.28 (16H,
m), 7.43 (8H, m); 13C NMR (75 MHz, CD2Cl2) d 55.6, 65.3,
71.1, 72.3, 87.1, 113.6, 127.4, 128.3, 128.6, 130.7, 135.6,
144.7, 144.7, 159.2; IR: 3432, 3057, 3032, 3001, 2931,
2836, 1608, 1583, 1510, 1491, 1463, 1447, 1414, 1300,
1251, 1223, 1180, 1155, 1070, 1033, 985, 902, 832, 796,
766, 755, 727, 708, 632, 590; MS (EI) m/z (rel. intensity):
726 ([M1], 1), 273 (100), 213 (8), 165 (9).
2,3,4,5-Tetra-O-benzyl-1,6-bis[(p-methoxyphenyl)(diphe-
nyl)methyl]-galactitol (24). Prepared as described above
1,6-Bis[(p-methoxyphenyl)(diphenyl)methyl]-galactitol (23).

2200
L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
starting from substrate 23 (4.95 g, 6.81 mmol). Colorless
crystals (6.71 g, 91%). mpˆ142±1438C 1H NMR
(300 MHz, CD2Cl2) d 3.43 (4H, d, Jˆ5.3 Hz), 3.76 (6H,
s), 3.98 (2H, m), 4.06 (2H, m), 4.40±4.65 (8H, m), 6.78
(4H, dt, Jˆ8.9, 2.5 Hz), 7.11 (4H, m), 7.29 (32H, m), 7.46
(8H, m); 13C NMR (75 MHz, CD2Cl2) d 55.5, 63.8, 72.9,
74.1, 78.8, 79.3, 86.9, 113.4, 127.1, 127.2, 127.6, 127.7,
127.9, 128.0, 128.2, 128.5, 128.6, 128.7, 128.8, 130.7,
135.9, 139.2, 139.3, 145.1, 159.0; IR: 3086, 3058, 3032,
2933, 2888, 2861, 2836, 1607, 1584, 1510, 1496, 1448,
1393, 1334, 1301, 1252, 1217, 1177, 1155, 1126, 1091,
1068, 1030, 1002, 987, 946, 901, 828, 797, 765, 736, 697,
632, 584; MS (EI) m/z (rel. intensity) 1086 ([M1], ,0.1),
363 (9), 273 (100), 91 (55).
dropwise (5 min) to a solution of oxalyl chloride (360 ml,
3.8 mmol) in CH2Cl2 (4 mL) at 2608C. The solution is
stirred for 2 min before diol 13 (500 mg, 0.92 mmol)
dissolved in CH2Cl2 (4 mL) is introduced during 5 min at
the same temperature. After stirring the resulting mixture
for an additional 10 min, Et3N (2.4 mL, 17.2 mmol) is
added at 2608C. The reaction mixture is kept at 2608C
for 15 min and is then allowed to warm to ambient tempera-
ture. The reaction is diluted with CH2Cl2 (100 mL), the
organic phase is successively washed with aq. HCl
(0.05 M, 2£20 mL), water (20 mL) and brine (2£20 mL),
dried (Na2SO4) and evaporated. Crude dialdehyde 14 thus
obtained is used in the next step without further puri®cation.
The commercially available Tebbe reagent (,0.5 M in tolu-
ene, 0.4 mmol, 0.8 mL) is diluted with THF (5 mL) and the
resulting solution is added dropwise over a period of 2 h to a
cooled solution (2408C) of the crude dialdehyde 14
(100 mg, 0.185 mmol) and pyridine (0.1 mL) in THF
(10 mL). The reaction mixture is slowly warmed to ambient
temperature and stirred for 30 min. The reaction is quenched
by addition of a few drops of aq. NaOH (2N) at 2108C, the
mixture is stirred for 20 min, insoluble residues are ®ltered
off through a pad of celite and the ®ltrate is concentrated.
Flash chromatography of the residue (hexane/EtOAc, 50:1)
affords diene 15 as a colorless syrup (39.1 mg, 42%).
[a]2D0ˆ114.98 (cˆ1.5, CHCl3); 1H NMR (300 MHz,
CD2Cl2) d 3.80 (2H, m), 4.07 (1H, dd, Jˆ5.7, 7.9 Hz),
4.14 (1H, dd, Jˆ6.1, 7.7 Hz), 4.27 (1H, d, Jˆ11.6 Hz),
4.39 (1H, d, Jˆ11.6 Hz), 4.56±4.63 (4H, m), 4.80 (1H, d,
Jˆ10.9 Hz), 4.81 (1H, d, Jˆ11.0 Hz), 5.25±5.43 (4H, m),
5.94 (1H, ddd, Jˆ7.8, 10.4, 17.2 Hz), 6.02 (1H, ddd, Jˆ8.0,
10.4, 17.1 Hz), 7.32 (20H, m); 13C NMR (75 MHz, CD2Cl2)
d 70.4, 70.9, 74.4, 75.6, 81.0, 81.7, 82.0, 82.1, 119.3, 119.7,
127.6, 127.7, 127.8, 127.85, 128.0, 128.1, 128.2, 128.3,
128.36, 128.4 (2£) 128.5, 128.6, 136.2, 136.6, 139.0,
139.2, 139.5, 139.6; IR: 3087, 3064, 3030, 2979, 2866,
1673, 1640, 1606, 1585, 1497, 1454, 1422, 1391, 1349,
1305, 1243, 1208, 1089, 1068, 1028, 997, 930, 734, 697,
599; MS (EI) m/z (rel. intensity) 443 ([(M2Bn)1], ,0.1),
181 (10), 147 (5), 91 (100); HRMS C36H38O4 calcd
535.2848, found 535.2840.
2,3,4,5-Tetra-O-benzyl-d-glucitol (13). H2SO4 conc.
(0.2 mL) is added to a cooled solution (08C) of substrate
12 (10.0 g, 9.2 mmol) in MeOH/CH2Cl2 (10:3, 150 mL).
After stirring for 1 h, the reaction is quenched by addition
of NaHCO3 (ca. 5 g) and the resulting slurry is stirred for
30 min. Filtration affords a clear solution which is dried
(Na2SO4) and concentrated. Flash chromatography (hex-
ane/EtOAc, 2:1) provides product 13 as a colorless syrup
1
(4.32 g, 87%). H NMR (300 MHz, CD2Cl2) d 2.09 (1H, t,
Jˆ5.5 Hz), 2.22 (1H, t, Jˆ5.6 Hz), 3.65 (1H, m), 3.75±3.90
(6H, m), 3.97 (1H, t, Jˆ4.7 Hz), 4.43±4.82 (m, 8H), 7.33
(20H, m); 13C NMR (75 MHz, CD2Cl2) d 60.9, 62.0, 72.0,
73.1, 74.5, 75.0, 78.8, 79.7, 80.1, 80.3, 128.0, 128.0, 128.1,
128.3, 128.4, 128.5, 128.7, 128.8, 128.9, 138.7, 138.8 (2x),
138.9; IR: 3442, 3088, 3063, 3030, 3007, 2929, 2876, 1606,
1586, 1496, 1454, 1396, 1352, 1308, 1250, 1209, 1091, 1066,
1028, 913 877, 735, 697, 602; MS (EI) m/z (rel. intensity)
451 ([(M2Bn)1], 2), 345 (8), 253 (6), 181 (29), 91 (100).
2,3,4,5-Tetra-O-benzyl-d-mannitol (19). Deprotection of
compound 18 (8.00 g, 7.36 mmol) was carried out as
described above providing diol 19 as a colorless syrup
1
(3.78 g, 94%). H NMR (300 MHz, CD2Cl2) d 2.14 (2H,
dd, Jˆ4.6, 7.6 Hz), 3.77 (4H, m), 3.90±4.00 (4H, m), 4.47
(2H, d, Jˆ11.5 Hz), 4.59 (2H, d, Jˆ10.7 Hz), 4.63 (2H, d,
Jˆ11.1 Hz), 4.77 (2H, d, Jˆ11.2 Hz), 7.34 (20H, m); 13C
NMR (75 MHz, CD2Cl2) d 60.3, 71.7, 74.8, 78.8, 80.0,
128.0, 128.1, 128.2, 128.7, 128.8, 138.6; IR: 3448, 3088,
3063, 3030, 2930, 2879, 1605, 1586, 1496, 1454, 1394,
1350, 1326, 1248, 1209, 1095, 1066, 1028, 913, 876, 848,
736, 698, 604; MS (EI) m/z (rel. intensity) 451 ([(M2Bn)1],
1), 181 (23), 91 (100).
(3R,4R,5R,6R)-3,4,5,6-Tetra(benzyloxy)-1,7-octadiene (21).
Diol 19 (205 mg, 0.377 mmol) was processed as described
above affording diene 21 as a colorless solid (94.7 mg,
1
47%). mpˆ66±678C; [a]2D0ˆ220.78 (cˆ1.9, CHCl3); H
NMR (300 MHz, CD2Cl2) d 3.82 (2H, d, Jˆ6.7 Hz), 4.06
(2H, t, Jˆ7.2 Hz), 4.27 (2H, d, Jˆ11.5 Hz), 4.45 (2H, d,
Jˆ10.9 Hz), 4.61 (2H, d, Jˆ11.6 Hz), 4.66 (2H, d,
Jˆ10.9 Hz), 5.38 (2H, d, Jˆ2.0 Hz), 5.43 (2H, d,
Jˆ1.9 Hz), 5.98 (2H, m), 7.28 (20H, m); 13C NMR
(75 MHz, CD2Cl2) d 70.3, 74.9, 80.7, 81.2, 119.9, 127.7,
127.8, 128.2, 128.2, 128.5, 128.7, 136.9, 139.0, 139.3; IR:
3088, 3062, 2978, 2919, 2874, 2846, 2825, 1642, 1606, 1585,
1497, 1452, 1420, 1389, 1342, 1325, 1302, 1281, 1206, 1173,
1142, e1114, 1095, 1069, 1027, 1042, 996, 949, 936, 903,
772, 734, 696, 600, 505; MS (EI) m/z (rel. intensity) 443
([(M2Bn)1], ,0.2), 279 (6), 189 (5), 181 (24), 147 (8),
91 (100). HRMS C36H38O4 calcd 535.2848, found 535.2839.
2,3,4,5-Tetra-O-benzyl-galactitol (25). Substrate 24
(6.31 g, 5.80 mmol) was deprotected as described above
affording product 25 as a colorless solid (2.80 g, 89%).
mpˆ114±1158C; 1H NMR (300 MHz, CD2Cl2) d 2.41
(2H, dt, Jˆ1.6, 6.3 Hz), 3.71±3.85 (6H, m), 3.97 (2H, d,
Jˆ5.4 Hz), 4.62 and 4.67 (4H, AB, Jˆ11.5 Hz), 4.72 (4H,
s), 7.32 (20H, m); 13C NMR (75 MHz, CD2Cl2) d 61.5, 72.9,
74.6, 80.2, 80.4, 127.9, 128.0, 128.2, 128.3, 128.6, 128.7,
138.8, 139.0; IR: 3475, 3087, 3063, 3030, 2926, 2875, 1509,
1497, 1453, 1397, 1334, 1250, 1216, 1109, 1068, 1028,
1004, 751, 697; MS (EI) m/z (rel. intensity) 451
([(M2Bn)1], 0.3), 91 (100).
(3R,4R,5R,6S)-3,4,5,6-Tetra(benzyloxy)-1,7-octadiene (15).
DMSO (540 ml, 7.6 mmol) in CH2Cl2 (2 mL) is added
(3Rp,4Sp,5Rp,6Sp)-3,4,5,6-Tetra(benzyloxy)-1,7-octadiene
(27). Obtained as a colorless solid (41.9 mg, 42%) from diol

L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
2201
1
25 (100 mg, 0.185 mmol) according to the procedure
outlined above. mpˆ84±858C; 1H NMR (300 MHz,
CDCl3) d 3.83 (2H, s), 4.20 (2H, d, Jˆ7.8 Hz), 4.30 (2H,
d, Jˆ11.8 Hz), 4.47 (2H, d, Jˆ11.4 Hz), 4.61 (2H, d,
Jˆ11.3 Hz), 4.62 (2H, d, Jˆ12.3 Hz), 5.25 (2H, d,
Jˆ10.6 Hz), 5.34 (2H, d, Jˆ17.3 Hz), 5.94 (2H, m), 7.26
(20H, m); 13C NMR (75 MHz, CDCl3) d 70.2, 74.4, 80.3,
81.5, 118.5, 127.3, 127.4, 127.6, 128.0, 128.1, 128.2, 136.6,
138.5, 138.7; IR: 3086, 3061, 3030, 3008, 2979, 2931, 2866,
1638, 1604, 1586, 1496, 1453, 1421, 1393, 1333, 1214,
1147, 1097, 1063, 1028, 1005, 937, 909, 760, 751, 738,
697, 591; MS (EI) m/z (rel. intensity) 443 ([M2Bn)1],
,0.2), 189 (5), 181 (21), 147 (10), 91 (100).
as a colorless syrup (123 mg, 71%). H NMR (300 MHz,
CDCl3): d 6.02 (2H, dd, Jˆ1.5, 3.2 Hz), 5.62 (2H, m), 3.99
(2H, dd, Jˆ1.2, 2.0 Hz), 2.05 (6H, s), 1.40 (6H, s). 13C NMR
(75 MHz, CDCl3): d 170.6 (s), 129.8 (d), 111.2 (s), 72.0 (d),
65.6 (d), 26.5 (q), 20.7 (q). IR: 3043, 2986, 2936, 2902,
1746, 1457, 1435, 1372, 1228, 1174, 1149, 1113, 1097,
1053, 1025, 941, 851, 824, 794. MS (EI) m/z (rel. intensity):
255 (32), 153 (19), 111 (47), 43 (100). The following
compounds have been obtained analogously:
(3R,4R,5R,6S)-3,4,5,6-Tetra(benzyloxy)-cyclohexene (31).
[a]2D0ˆ217.88 (cˆ1.05, CHCl3); 1H NMR (300 MHz,
CD2Cl2) d 3.57 (1H, dd, Jˆ3.5, 9.5 Hz), 4.04±4.16 (3H,
m), 4.65±5.00 (8H, m), 5.88 (2H, m), 7.35 (20H, m); 13C
NMR (75 MHz, CD2Cl2) d 72.1, 72.4, 72.5, 72.9, 75.2, 80.2,
80.3, 80.5, 126.6, 127.7, 127.8, 127.9, 128.1, 128.2, 128.3,
128.5, 128.6, 131.1, 139.2, 139.4, 139.6; IR: 3087, 3062,
3031, 2917, 2865, 1604, 1585, 1496, 1453, 1388, 1365,
1338, 1308, 1261, 1207, 1163, 1123, 1091, 1073, 1027,
911, 734, 697; MS (EI) m/z (rel. intensity) 415
([(M2Bn)1], 2), 292 (11), 266 (9), 201 (7), 91 (100).
HRMS C34H34O4 calcd 507.2535, found 507.2540.
(3S,4S,5S,6S)-3,6-Dihydroxy-4,5-(isopropylidenedioxy)-
1,7-octadiene (29). A solution of Dibal-H (1 M in toluene,
28.9 mL, 28.9 mmol) is added dropwise to a solution of
(2R,3R)-2,3-O-isopropylidene tartrate 28 (3.0 g, 13.8
mmol) in toluene (50 mL) at 2788C. The resulting mixture
is stirred at that temperature for 2.5 h prior to the addition of
vinylmagnesium bromide (1 M in THF, 41.3 mL,
41.3 mmol). Stirring at 2788C is continued for another
2 h before the mixture is allowed to reach ambient tempera-
ture. For work-up, the reaction is carefully quenched with
sat. aq. NH4Cl (100 mL), the aqueous layer is repeatedly
extracted with EtOAc, the combined organic layers are
washed with water and brine, dried (MgSO4) and evapo-
rated. Flash chromatography of the crude product with hex-
ane/EtOAc (3/1) allows to separate the individual isomers
affording diol 29 as the major product in form of a colorless
(3R,4R,5R,6R)-3,4,5,6-Tetra(benzyloxy)-cyclohexene (32).
[a]2D0ˆ2111.58 (cˆ1.2, CHCl3); 1H-NMR (300 MHz,
CD2Cl2) d 4.06 (2H, d, Jˆ2.5 Hz), 4.29 (2H, m), 4.58±
4.75 (8H, m), 5.84 (2H, s), 7.31 (20H, m); 13C NMR
(75 MHz, CD2Cl2) d 72.0, 73.6, 74.1, 76.7, 127.8, 127.9,
128.1, 128.2, 128.3, 128.6, 139.3, 139.4; IR: 3087, 3062,
3030, 2864, 1469, 1453, 1202, 1088, 1073, 1027, 952, 910,
735, 697; MS (EI) m/z (rel. intensity) 415 ([(M2Bn)1], 1),
266 (16), 91 (100). HRMS C34H34O4 calcd 507.2535, found
507.2537.
1
syrup (1.23 g, 41%). H NMR (300 MHz, CDCl3): d 5.93
(2H, ddd, Jˆ16.5, 10.4, 6.0 Hz), 5.35 (2H, ddd, Jˆ16.5, 1.5,
1.0 Hz), 5.24 (2H, ddd, Jˆ10.4, 1.5, 1.0 Hz), 4.09±4.22
(2H, m), 3.82±4.01 (2H, m), 2.82 (2H, bs, ±OH), 1.37
(6H, s). 13C NMR (75 MHz, CDCl3): d 137.5 (d), 117.5
(t), 109.8 (s), 82.1 (d), 74.0 (d), 27.3 (q). IR: 3382, 3086,
2987, 2935, 2893, 1645, 1457, 1429, 1381, 1373, 1244,
1217, 1166, 1078, 1055, 996, 927, 879. MS (EI) m/z (rel.
intensity): 199 (7), 157 (8), 101 (37), 59 (100).
(3Sp,4Rp,5Sp,6Rp)-3,4,5,6-Tetra(benzyloxy)-cyclohexene
(33). 1H NMR (300 MHz, CD2Cl2) d 3.91 (2H, d,
Jˆ5.1 Hz), 4.17 (2H, d, Jˆ5.1 Hz), 4.61 (4H, s), 4.67
(4H, s), 5.86 (2H, d, Jˆ1.4 Hz), 7.33 (20H, m); 13C NMR
(75 MHz, CD2Cl2) d 72.2, 73.0, 75.9, 77.8, 127.8, 127.9,
128.0, 128.2, 128.6, 128.7, 139.2; IR: 3086, 3062, 3030,
2867, 1605, 1585, 1469, 1453, 1385, 1329, 1304, 1247,
1206, 1117, 1132, 1097, 1061, 1040, 1027, 911, 863, 805,
736, 696, 604; MS (EI) m/z (rel. intensity) 415 ([(M2Bn)1],
1), 266 (18), 91 (100). HRMS C34H34O4 calcd 507.2535,
found 507.2539.
(3S,4S,5S,6S)-3,6-Diacetoxy-4,5-(isopropylidenedioxy)-1,7-
octadiene (30). A solution of diol 29 (0.40 g, 1.87 mmol)
and Ac2O (0.39 g, 3.8 mmol) in CH2Cl2 (10 mL) and pyri-
dine (10 mL) is re¯uxed for 3 h. Standard extractive work-
up followed by ¯ash chromatography (hexane/EtOAc, 10/1)
affords the title compound as a colorless syrup (0.46 g,
83%). 1H NMR (300 MHz, CDCl3): d 5.87 (2H, ddd,
Jˆ6.1, 7.2, 14.3 Hz), 5.29±5.36 (6H, m), 3.96 (2H, m),
2.09 (6H, s), 1.37 (6H, s). 13C NMR (75 MHz, CDCl3): d
169.8, 131.8, 120.0, 110.7, 78.9, 74.5, 26.9, 21.0. IR: 3086,
2989, 2937, 1747, 1646, 1455, 1430, 1373, 1233, 1169,
1107, 1072, 1025, 996, 937, 869, 611, 463 cm21. MS (EI)
m/z (rel. intensity): 283 (11), 199 (14), 141 (29), 81 (10), 43
(100).
(3S,4S,5S,6S)-3,6-Dihydroxy-4,5-(isopropylidenedioxy)-
cyclohexene (34). 1H NMR (300 MHz, CDCl3): d 5.98 (2H,
dd, Jˆ3.2, 1.5 Hz), 4.49 (bd, 2H), 3.94 (2H, dd, Jˆ1.9,
1.3 Hz), 2.63 (2H, bs, ±OH), 1.48 (6H, s); 13C NMR
(75 MHz, CDCl3): d 129.4 (d), 109.5 (s), 72.4 (d), 63.7
(d), 25.9 (q). IR: 3344, 3042, 2988, 2932, 2903, 1449,
1371, 1336, 1279, 1231, 1170, 1149, 1130, 1093, 1066,
1019, 969, 933, 842, 818, 706, 609, 552, 508. MS (EI) m/
z (rel. intensity): 171 (75), 111 (100), 99 (52), 83 (44), 59
(31), 43 (78).
Representative procedure for RCM catalyzed by
complex 3a: (3S,4S,5S,6S)-3,6-diacetoxy-4,5-(isopropyli-
denedioxy)-cyclohexene (35). A solution of diene 30
(193.4 mg, 0.64 mmol) and complex 3a (5.3 mg,
0.0064 mmol, 1 mol%) in CH2Cl2 (150 mL) is re¯uxed for
5 h until TLC shows complete conversion of the substrate.
Evaporation of the solvent followed by ¯ash chroma-
tography (hexane/EtOAc, 10/1) provides cyclohexene 35
Acknowledgements
Generous ®nancial support by the Deutsche Forschungsge-
meinschaft (Leibniz Program) and the Fonds der Chemischen
Â
Industrie (Kekule Stipend to L. A.) is acknowledged with

2202
L. Ackermann et al. / Tetrahedron 56 (2000) 2195±2202
18. (a) Okazoe, T.; Takai, K.; Utimoto, K. J. Am. Chem. Soc.
1987, 109, 951. (b) Review: FuÈrstner, A. Chem. Rev. 1999, 99, 991.
19. (a) Review: Ager, D. J. Org. React. 1990, 38, 1. (b) For
successful applications to closely related acyclic carbohydrate-
derived mono-aldehydes see: FuÈrstner, A.; Weidmann, H. J. Org.
Chem. 1990, 55, 1363. (c) FuÈrstner, A.; Baumgartner, J.
Tetrahedron 1993, 49, 8541.
gratitude. We thank Mrs Helga Krause and Mr A. Milchereit
for the preparation of compounds 34 and 35.
References
1. Recent reviews: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998,
54, 4413. (b) FuÈrstner, A. Top. Catal. 1997, 4, 285. (c) Schuster,
M.; Blechert, S. Angew. Chem. Int. Ed. Engl. 1997, 36, 2036. (d)
FuÈrstner, A. Top. Organomet. Chem. 1998, 1, 37. (e) Ivin, K. J.,
Mol, J. C. Ole®n Metathesis and Methathesis Polymerization;
Academic Press: New York; 2nd ed., 1997.
20. (a) Review: Pine, S. H. Org. React. 1993, 43, 1. (b) Tebbe,
F. N.; Parshall, G. W.; Reddy, G. S. J. Am. Chem. Soc. 1978, 100,
3611.
21. For carbocycle syntheses from carbohydrate precursors via
RCM see the following for leading references: (a) Ziegler, F. E.;
Wang, Y. J. Org. Chem. 1998, 63, 7920. (b) Sellier, O.; van de
Weghe, P.; Le Nouen, D.; Strehler, C.; Eustache, J. Tetrahedron
Â
2. Herisson, J.-L.; Chauvin, Y. Makromol. Chem. 1970, 141, 161.
3. (a) Schrock, R. R.; Murdzek, J. S.; Bazan, G. C.; Robbins, J.;
DiMare, M.; O'Regan, M. J. Am. Chem. Soc. 1990, 112, 3875. (b)
Review: Schrock, R. R. Top. Organomet. Chem. 1998, 1, 1.
4. (a) Nguyen, S. T.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc.
1993, 115, 9858. (b) Schwab, P.; Grubbs, R. H.; Ziller, J. W. J. Am.
Chem. Soc. 1996, 118, 100.
Â
Lett. 1999, 40, 853. (c) Ovaa, H.; Codee, J. D. C.; Lastdrager, B.;
Overkleeft, H. S.; van der Marel, G. A.; van Boom, J. H.
Tetrahedron Lett. 1999, 40, 5063. (d) Kapferer, P.; Sarabia, F.;
Vasella, A. Helv. Chim. Acta 1999, 82, 645. (e) Seepersaud, M.;
Bucala, R.; Al-Abed, Y. Z. Naturforsch. 1999, 54b, 565. (f)
Sellier, O.; van de Weghe, P.; Eustache, J. Tetrahedron Lett.
5. For the preparation and reactivity of ruthenium carbene
complexes bearing two imidazol-2-ylidene ligands see: Weskamp,
T.; Schattenmann, W. C.; Spiegler, M.; Herrmann, W. A. Angew.
Chem. Int. Ed. Engl. 1998, 37, 2490.
Â
1999, 40, 5859. (g) Ovaa, H.; Codee, J. D. C.; Lastdrager, B.;
Overkleeft, H. S.; van der Marel, G. A.; van Boom, J. H.
Tetrahedron Lett. 1999, 40, 7987.
22. Resin glycoside syntheses via RCM: (a) FuÈrstner, A.;
6. Review on N-heterocyclic carbenes: Herrmann, W. A.;
È
Kocher, C. Angew. Chem. Int. Ed. Engl. 1997, 36, 2162.
7. Huang, J.; Stevens, E. D.; Nolan, S. P.; Petersen, J. L. J. Am.
Chem. Soc. 1999, 121, 2674.
Muller, T. J. Am. Chem. Soc. 1999, 121, 7814. (b) Furstner, A.;
È
MuÈller, T. J. Org. Chem. 1998, 63, 424.
È
23. For diverse other applications of metathesis in carbohydrate
chemistry see the following for leading references: (a)
Leewenburgh, M. A.; Kulker, C.; Duynstee, H. I.; Overkleeft,
H. S.; van der Marel, G. A.; van Boom, J. H. Tetrahedron 1999,
55, 8253. (b) Calimente, D.; Postema, M. H. D. J. Org. Chem.
1999, 64, 1770. (c) Holt, D. J.; Barker, W. D.; Jenkins, P. R.;
Davies, D. L.; Garratt, S.; Fawcett, J.; Russell, D. R.; Ghosh, S.
Angew. Chem. 1998, 110, 3486. (d) Rainier, J. D.; Allwein, S. P.
J. Org. Chem. 1998, 63, 5310. (e) Ghosh, A. K.; Cappiello, J.;
Shin, D. Tetrahedron Lett. 1998, 39, 4651. (f) El Sukkari, H.;
Gesson, J.-P.; Renoux, B. Tetrahedron Lett. 1998, 39, 4043. (g)
Overkleeft, H. S.; Bruggeman, P.; Pandit, U. K. Tetrahedron Lett.
1998, 39, 3869. (h) Oguri, H.; Sasaki, S.; Oishi, T.; Hirama, M.
Tetrahedron Lett. 1999, 40, 5405. (i) Dirat, O.; Vidal, T.;
Langlois, Y. Tetrahedron Lett. 1999, 40, 4801. (j) SchuÈrer, S. C.;
Blechert, S. Chem. Commun. 1999, 1203.
8. Scholl, M.; Trnka, T. M.; Morgan, J. P.; Grubbs, R. H.
Tetrahedron Lett. 1999, 40, 2247.
9. (a) Ackermann, L.; FuÈrstner, A.; Weskamp, T.; Kohl, F. J.;
Herrmann, W. A. Tetrahedron Lett. 1999, 40, 4787. (b)
Weskamp, T.; Kohl, F. J.; Hieringer, W.; Gleich, D.; Herrmann,
W. A. Angew. Chem. 1999, 111, 2573.
10. For timely and comprehensive reviews see: (a) Hudlicky T.;
Entwistle, D. A.; Pitzer, K. K.; Thorpe, A. J. Chem. Rev. 1996, 96,
1195. (b) Balci, M.; SuÈtbeyaz, Y.; Secen, H. Tetrahedron 1990, 46,
3715. (c) Balci, M. Pure Appl. Chem. 1997, 69, 97. (d)
Dumortier, L., Liu, P., van der Eycken, J., Vandewalle, M. in:
Carbohydrate Mimics, Chapleur, Y. Ed.; Wiley-VCH: Weinheim,
1998, p 209. (e) Billington, D. C., Perron-Sierra, F., Picard, I.,
Beaubras, S., Duhault, J., Espinal, J., Challal, S. in Carbohydrate
Mimics, Chapleur, Y., Ed.; Wiley-VCH: Weinheim, 1998, p 433.
(f) For a general review on the synthesis of carbocycles from
carbohydrate precursors see: Ferrier, R. J.; Middleton, S. Chem.
Rev. 1993, 93, 2779.
24. A related observation has been made in one case by Eustache
et al., cf. Ref. 21b.
25. For previous studies on RCM from our laboratory see i. a.: (a)
FuÈrstner, A.; Langemann, K. J. Org. Chem. 1996, 61, 3942. (b)
FuÈrstner, A.; Langemann, K. Synthesis 1997, 792. (c) FuÈrstner, A.;
Langemann, K. J. Am. Chem. Soc. 1997, 119, 9130. (d)
FuÈrstner, A.; Kindler, N. Tetrahedron Lett. 1996, 37, 7005. (e)
FuÈrstner, A.; Langemann, K. J. Org. Chem. 1996, 61, 8746. (f)
FuÈrstner, A.; MuÈller, T. Synlett 1997, 1010. (g) FuÈrstner, A.;
Gastner, T.; Weintritt, H. J. Org. Chem. 1999, 64, 2361. (h)
FuÈrstner, A.; Seidel, G.; Kindler, N. Tetrahedron 1999, 55, 8215.
(i) FuÈrstner, A.; Hill, A. F.; Liebl, M.; Winton-Ely, J. D. E. T.
Chem. Commun. 1999, 601. (j) FuÈrstner, A.; Ackermann, L.
Chem. Commun. 1999, 95. (k) FuÈrstner, A.; Picquet, M.; Bruneau,
C.; Dixneuf, P. H. Chem. Commun. 1998, 1315. (l) FuÈrstner, A.;
Koch, D.; Langemann, K.; Leitner, W.; Six, C. Angew. Chem. Int.
Ed. Engl. 1997, 36, 2466. (m) FuÈrstner, A.; Szillat, H.; Gabor, B.;
Mynott, R. J. Am. Chem. Soc. 1998, 120, 8305.
11. Kornienko, A.; d'Alarcao, M. Tetrahedron: Asymmetry 1999,
10, 827.
12. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic
Synthesis, 2nd; Wiley: New York, 1991.
13. Mancuso, A. J.; Swern, D. Synthesis 1981, 165.
14. Ley, S. V.; Norman, J.; Grif®th, W. P.; Marsden, S. P.
Synthesis 1994, 639.
15. (a) Dess, D. B.; Martin, J. C. J. Org. Chem. 1983, 48, 4155. (b)
Meyer, S. D.; Schreiber, S. L. J. Org. Chem. 1994, 59, 7549.
16. Review: Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89,
863. (b) Bestmann, H. J.; Vostrovsky, O. Top. Curr. Chem. 1983,
109, 85.
17. (a) Okazoe, T.; Hibino, J.; Takai, K.; Nozaki, H. Tetrahedron
Lett. 1985, 26, 5581. (b) Takai, K.; Hotta, Y.; Oshima, K.; Nozaki,
H. Bull. Chem. Soc. Jpn. 1980, 53, 1698.