Synthesis of (6,6′)-C-linked pseudodisaccharides

Article abstract of DOI:10.1080/07328300903267577

A series of (6,6′)-C-linked pseudodisaccharides has been prepared using a general synthetic strategy of olefin metathesis in the presence of Grubbs second-generation catalyst. Yields were excellent in every case.

Full text of DOI:10.1080/07328300903267577

This article was downloaded by: [University of Florida]
On: 04 October 2014, At: 09:00
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Carbohydrate Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lcar20
Synthesis of (6,6′)-C-Linked
Pseudodisaccharides
Chinmoy Mukherjee a & Anup Kumar Misra a
a Division of Molecular Medicine , Bose Institute , A.J.C. Bose
Centenary Campus, P-1/12, C.I.T. Scheme VII M, Kolkata, 700054,
India
Published online: 17 Nov 2009.
To cite this article: Chinmoy Mukherjee & Anup Kumar Misra (2009) Synthesis of (6,6′)-C-Linked
Pseudodisaccharides, Journal of Carbohydrate Chemistry, 28:9, 475-482
To link to this article: http://dx.doi.org/10.1080/07328300903267577
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Journal of Carbohydrate Chemistry, 28:475–482, 2009
ꢀ
C
Copyright Taylor & Francis Group, LLC
ISSN: 0732-8303 print / 1532-2327 online
DOI: 10.1080/07328300903267577
Synthesis of (6,6ꢁ)-C-Linked
Pseudodisaccharides
Chinmoy Mukherjee and Anup Kumar Misra
Division of Molecular Medicine, Bose Institute, A.J.C. Bose Centenary Campus,
P-1/12, C.I.T. Scheme VII M, Kolkata 700054, India
A series of (6,6ꢁ)-C-linked pseudodisaccharides has been prepared using a general syn-
thetic strategy of olefin metathesis in the presence of Grubbs second-generation cata-
lyst. Yields were excellent in every case.
Keywords C-glycoside; Pseudodisaccharide; Grubbs catalyst; Olefin metathesis
INTRODUCTION
Pseudodisaccharides are structural analogs of natural disaccharides in which
the linkage is formed without involvement of the anomeric center of the
monosaccharides. Two monosaccharide units may be connected together
through an ether, thio, carbo, or imino linkage.[1] In general, sugars in which
the ether linkage region is replaced by a methylene group are termed carba-
sugars.[2] Carbasugars can act as stable glycosidase inhibitors because of their
stability in the enzymatic reaction conditions.[3] A few years back, Perez and
coworkers[4] reported a compound named “Coyolosa” from the root extract of
Acrocomia mexicana having significant hypoglycemic activity (Fig. 1). In the
preliminary report, they also suggested that Coyolosa is a pseudodisaccharide
in which two D-allose units were interconnected through a 6,6ꢁ-ether linkage.
Afterward, Haines[5] carried out extensive studies for the verification of the
structure of Coyolosa and confirmed that it is not a 6,6ꢁ-ether-linked disac-
charide. In an independent chemical approach, Ikegami et al.[6] proposed the
structure of Coyolosa as 6,6ꢁ-ether-connected D-mannose. In the recent past,
a number of elegant methods appeared in the literature for the synthesis
of ether-linked pseudodisaccharides for their possible use as glycosidase in-
hibitors.[7,8] It is expected that replacement of an ether linkage by a methylene
Received July 10, 2009; accepted August 17, 2009.
Address correspondence to Anup Kumar Misra, Division of Molecular Medicine, Bose
Institute, P-1/12, C.I.T. Scheme VII M, Kolkata 700054, India. E-mail: akmisra69@
rediffmail.com
475

C. Mukherjee & A.K. Misra
476
Figure 1: Proposed structure of Coyolosa.[4]
group could result stable glycomimetics for their bioevaluation. However, re-
ports of preparation of 6,6ꢁ-carbon-linked pseudodisaccharides are scarce in
literature. A few reports for the preparation of (1,1ꢁ)- and (1,6ꢁ)-carbon-linked
pseudodisaccharides are available in the literature[2] using olefin metathesis.
As part of the ongoing program toward the preparation of stable glycomimetics,
we report herein the synthesis of four (6,6ꢁ)-carbon-linked pseudodisaccharides
applying the olefin metathesis[9] technique.
RESULTS AND DISCUSSION
A general synthetic approach has been adopted for the preparation of (6,6ꢁ)-
carba pseudodisaccharides starting from a series of suitably functional-
ized monosaccharide units. Following literature-reported methods, methyl
2,3,4-tri-O-benzyl-α-D-glucopyranoside (3a), methyl 2,3,4-tri-O-benzyl-α-D-
galactopyranoside (3b), methyl 2,3,4-tri-O-benzyl-α-D-mannopyranoside (3c),
and methyl 2,3,4-tri-O-benzyl-β-D-allopyranoside (3d) were prepared in ex-
cellent yield starting from compounds 2a–d.[10–13] Swern oxidation followed
by Wittig olefination of compounds 2a–d furnished compounds 3a,[14] 3b,[15]
3c,[16] and 3d in excellent yield (Sch. 1). Homo-coupling of olefin deriva-
tives (3a–d) in the presence of Grubbs second-generation catalyst[17] afforded
(1,6ꢁ)-carba-linked pseudodisaccharide derivatives (4a–d) in satisfactory yield,
which on hydrogenation over Pearlmann’s catalyst[18] furnished deprotected
pseudodisaccharide derivatives (5a–d) in excellent yield. Structures of all
Scheme 1: Reagent: (a) (CH3)2SO, (COCl)2, Et3N, CH2Cl2, −78◦C; (b) CH3PPh3I, n-BuLi, THF,
−78◦C (72% for 3a, 70% for 3b, 73% for 3c, 69% for 3d).

Synthesis of (6,6ꢁ)-C-Linked Pseudodisaccharides
477
Scheme 2: Reagents: (a) Grubbs 2nd cat. (10 mol%), CH2Cl2, 45◦C, 8 h (69% for 4a, 70% for
4b, 69% for 4c, 67% for 4d); (b) 20% Pd(OH)2/C, CH3OH-EtOAc (3:1), rt, 24 h (85% for 5a, 82%
for 5b, 82% for 5c, 78% for 5d).
compounds were confirmed by NMR and mass spectral analysis (Sch. 2,
Fig. 2).
In summary, a general synthetic approach for the preparation of a series
of pseudo-C-disaccharide derivatives was developed using olefin metathesis in
the presence of second-generation Grubbs catalyst. The reaction condition is
high yielding and reproducible. Following a similar approach, a large number
of hydrolytically stable C-disaccharide derivatives can be synthesized.
EXPERIMENTAL
General Methods
All the reactions were monitored by thin layer chromatography over silica
gel-coated TLC plates. The spots on TLC were visualized by warming ceric
sulphate (2% Ce(SO4)2 in 2N H2SO4) sprayed plates on a hot plate. Silica gel
1
230–400 mesh was used for column chromatography. H and 13C NMR was
recorded on a Bruker Advance DPX 300 MHz using TMS as internal reference.
Chemical shift value is expressed in δ ppm. Elementary analysis was carried
out on Carlo ERBA-1108 analyzer. Optical rotations were measured at 25◦C
Figure 2: Deprotected (6,6ꢁ)-carbon-linked pseudodisaccharide derivatives.

C. Mukherjee & A.K. Misra
478
on a Rudolf Autopol III polarimeter. Commercially available grades of organic
solvents of adequate purity are used in many reactions.
General Experimental Procedure for the Preparation of methyl
2,3,4-tri-O-benzyl-6,7-dideoxy-α/β-D-glyco-hept-6-
enopyranoside (3a–d)
A solution of oxalyl chloride (455 µL, 5.4 mmol) in THF (2 mL) and CH2Cl2
(2 mL) was cooled to −78◦C. A solution of Me2SO (765 µL, 10.8 mmol) in
CH2Cl2 (3 mL) was slowly added to the cooled reaction mixture at −78◦C and
the mixture was stirred for 10 min at same temperature. A solution of com-
pound 2a–d (1 g, 2.15 mmol) in CH2Cl2 (5 mL) was added slowly to the reaction
mixture and it was stirred for 1 h at −60◦C. The mixture was cooled to −78◦C
and a solution of Et3N (3 mL, 21.5 mmol) in CH2Cl2 (3 mL) was added during
15 min. After stirring at −78◦C for 30 min, the reaction mixture was warmed
to rt and H2O (4 mL) was added. The organic layer was separated and the
aqueous layer was extracted with CH2Cl2 (3 × 20 mL). The combined organic
layer was then dried (Na2SO4), filtered, and concentrated under reduced pres-
sure to give the crude aldehyde. The crude aldehyde was then used directly for
the next step. To a suspension of methyl triphenylphosphonium iodide (5.2 g,
12.9 mmol) in dry THF (30 mL) at −78◦C was added n-BuLi (4 mL, 1.6 M solu-
tion in THF) and the mixture was stirred for 15 min at the same temperature.
The dried crude aldehyde in dry THF (10 mL) was then added to it and the
reaction mixture was warmed to rt. After 1 h of stirring at rt, water (15 mL)
was added and the reaction mixture was extracted with ethyl acetate (3 ×
30 mL). The combined organic layer was dried (Na2SO4), filtered, and concen-
trated under reduced pressure and the crude product was purified over SiO2
using hexane-EtOAc (8:1) as eluant to give pure product 3a–d as colorless oil.
All known compounds (3a–c) gave acceptable NMR spectra that matched data
reported in the cited references.
Methyl 2,3,4-tri-O-benzyl-6,7-dideoxy-β-D-allo-hept-6-
enopyranoside (3d)
25
Yield: 685 mg, 69%; [α]D + 39.2 (c 1.0, CHCl3); IR (neat): 3020, 2361,
1593, 1216, 762, 670 cm−1; H NMR (CDCl3, 300 MHz): δ 7.38–7.21 (m, 15 H,
1
Ar-H), 5.99–5.88 (m, 1 H, H-6), 5.45–5.38 (m, 1 H, H-7a), 5.23–5.19 (m, 1 H,
H-7b), 4.88–4.78 (m, 4 H, H-1, PhCH2), 4.58 (d, J = 12.2 Hz, 1 H, PhCH2), 4.46
(d, J = 11.7 Hz, 1 H, PhCH2), 4.40 (d, J = 11.8 Hz, 1 H, PhCH2), 4.37–4.32
(m, 1 H, H-5), 4.03–4.01 (m, 1 H, H-3), 3.55 (s, 3 H, OCH3), 3.17 (dd, J =
7.9, 2.6 Hz, 1 H, H-2), 3.10 (dd, J = 9.6, 2.4 Hz, 1 H, H-4); 13C NMR (CDCl3,
75 MHz): δ 139.0–116.9 (aromatic and olefinic carbons), 101.8 (C-1), 80.0, 79.1,

Synthesis of (6,6ꢁ)-C-Linked Pseudodisaccharides
479
75.1, 74.4, 73.0, 72.7, 71.9, 56.8; ESI-MS: m/z = 483.2 [M+Na]+; Anal. Calcd.
for C29H32O5 (460.22): C, 75.63; H, 7.00. Found: C, 75.45; H, 7.20.
General Experimental Procedure for the Olefin Metathesis of
Compounds 3a–d: Preparation of Compounds 4a–d
The solution of compound 3a–d (650 mg, 1.41 mmol) in CH2Cl2 (5 mL) was
bubbled with argon gas, followed by the addition of Grubbs second-generation
ruthenium catalyst (60 mg, 0.07 mmol). After stirring for 8 h at 45◦C, the reac-
tion mixture was concentrated in vacuo and purified over SiO2 using hexane-
EtOAc (6:1) as eluant to give pure compound 4a–d as colorless oil, which was
directly used for the next step without further purification of the isomers.
General Experimental Procedure for the Preparation of Methyl
(6-deoxy-α/β-D-glycopyranosyl)-(6→6ꢀ)-C-6-deoxy-α/β-D-
glycopyranoside (5a–d)
To the solution of compound 4a–d (400 mg, 0.45 mmol) in CH3OH:EtOAc
(3:1, 20 mL) was added 20% Pd(OH)2/C (50 mg) and the reaction mixture was
allowed to stir at rt under a positive pressure of hydrogen for 24 h. The reaction
mixture was filtered through a Celite bed and evaporated to dryness to give
compound 5a–d as white amorphous powder.
Methyl (Methyl 6-deoxy-α-D-gluco-hept-6-enopyranosyl)-6-
deoxy-α-D-gluco-hept-6-enopyranoside (5a)
25
Yield: 135 mg, 85%; [α]D + 135.7 (c 1.0, H2O). The proton integration in
the 1H NMR and carbon signals in the 13C NMR spectra appeared as monomer
1
because of the presence of the plane of symmetry in the molecule; H NMR
(D2O, 300 MHz): δ 4.81 (d, J = 3.6 Hz, 2 H), 3.69–3.58 (m, 6 H), 3.45 (s, 6 H),
3.26 (t, J = 9.2 Hz each, 2 H), 2.04–1.95 (m, 2 H), 1.74–1.62 (m, 2 H); 13C
NMR (D2O, 75 MHz): δ 99.1, 73.3, 73.0, 71.4, 70.4, 55.0, 26.1; ESI-MS: m/z =
377.3 [M+Na]+; Anal. Calcd. for C14H26O10 (354.15): C, 47.45; H, 7.40. Found:
C, 47.30; H, 7.60.
Methyl (Methyl 6-deoxy-α-D-galacto-hept-6-enopyranosyl)-6-
deoxy-α-D-galacto-hept-6-enopyranoside (5b)
25
Yield: 130 mg, 82%; [α]D + 146 (c 1.0, H2O). The proton integration in
the 1H NMR and carbon signals in the 13C NMR spectra appeared as monomer
1
because of the presence of the plane of symmetry in the molecule; H NMR
(D2O, 300 MHz): δ 4.82–4.81 (m, 2 H), 3.89–3.87 (m, 4 H), 3.83–3.82 (m, 4 H),
3.42 (s, 6 H), 1.80–1.76 (m, 2 H), 1.69–1.66 (m, 2 H); 13C NMR (D2O, 75 MHz):

C. Mukherjee & A.K. Misra
480
δ 99.5, 70.6, 70.0, 69.7, 68.2, 55.1, 26.1; ESI-MS: m/z = 377.2 [M+Na]+; Anal.
Calcd. for C14H26O10 (354.15): C, 47.45; H, 7.40. Found: C, 47.32; H, 7.65.
Methyl (Methyl 6-deoxy-α-D-manno-hept-6-enopyranosyl)-6-
deoxy-α-D-manno-hept-6-enopyranoside (5c)
25
Yield: 130 mg, 82%; [α]D + 87.1 (c 1.0, H2O). The proton integration in
the 1H NMR and carbon signals in the 13C NMR spectra appeared as monomer
1
because of the presence of the plane of symmetry in the molecule; H NMR
(D2O, 300 MHz): δ 4.74 (d, J = 1.6 Hz, 2 H), 3.95 (dd, J = 3.4, 1.7 Hz, 2 H),
3.74 (dd, J = 9.1, 3.4 Hz, 2 H), 3.60–3.46 (m, 4 H), 3.43 (s, 6 H), 2.06–1.96 (m,
2 H), 1.79–1.68 (m, 2 H); 13C NMR (D2O, 75 MHz): δ 100.8, 71.4, 70.4, 70.3,
69.9, 54.7, 26.3; ESI-MS: m/z = 377.3 [M+Na]+; Anal. Calcd. for C14H26O10
(354.15): C, 47.45; H, 7.40. Found: C, 47.32; H, 7.60.
Methyl (Methyl 6-deoxy-β-D-allo-hept-6-enopyranosyl)-6-deoxy-
β-D-allo-hept-6-enopyranoside (5d)
Yield: 125 mg, 78%; [α]D25—17.1 (c 1.0, H2O). The proton integration in
the 1H NMR and carbon signals in the 13C NMR spectra appeared as monomer
1
because of the presence of the plane of symmetry in the molecule; H NMR
(D2O, 300 MHz): δ 4.61 (d, J = 8.2 Hz, 2 H), 4.17 (brs, 2 H), 3.77 (t, J = 9.3 Hz,
2 H), 3.58 (s, 6 H), 3.49–3.38 (m, 4 H), 2.05–2.00 (m, 2 H), 1.72–1.67 (m, 2 H);
13C NMR (D2O, 75 MHz): δ 101.1, 72.2, 71.2, 70.8, 70.6, 56.9, 26.5; ESI-MS:
m/z = 377.2 [M+Na]+; Anal. Calcd. for C14H26O10 (354.15): C, 47.45; H, 7.40.
Found: C, 47.30; H, 7.58.
ACKNOWLEDGEMENTS
C.M. thanks CSIR, New Delhi, for providing a Senior Research Fellowship.
This project was funded by the Department of Science and Technology (DST),
New Delhi, through the Ramanna Fellowship (AKM) (Project no. SR/S1/RFPC-
06/2006).
REFERENCES
1. (a) Roy, R.; Dominique, R.; Das, S.K. Extended alkenyl glycosides by Ruthenium-
catalyzed cross-metathesis reaction and application toward novel C-linked pseudodis-
accharides. J. Org. Chem. 1999, 64, 5408–5412; (b) Maity, J.K.; Mukherjee, S.; Drew,
M.G.B.; Achari, B.; Mandal, S.B. First example of 5/6-O-linked pseudosaccharides: syn-
thesis of bicyclic nucleosides containing azido or extended carbohydrate moiety. Car-
bohydr. Res. 2007, 342, 2511–2521; (c) Szilagyi, L.; Illyes, T.-Z.; Herczegh, P. Elabo-
ration of a novel type of interglycosidic linkage: syntheses of disulfide disaccharides.
Tetrahedron Lett. 2001, 42, 3901–3903; (d) McCort, I.; Dureault, A.; Depezay, J.-C.
Synthesis of ester-and amide-linked pseudo-azadisaccharides via coupling of D-glucose

Synthesis of (6,6ꢁ)-C-Linked Pseudodisaccharides
481
with 6-amino-6-deoxy-2,5-imino-D-glucitol. Tetrahedron Lett. 1998, 39, 4463–4466;
(e) Uhrig, M.L.; Szilagyi, L.; Kover, K.E.; Varela, O. Synthesis of non-glycosidic
4,6ꢁ-thioether-linked disaccharides as hydrolytically stable glycomimetics. Carbohydr.
Res. 2007, 342, 1841–1849; (f) Kroutil, J.; Budesinsky, M. Preparation of diamino
pseudodisaccharide derivatives from 1,6-anhydro-β-D-hexopyranoses via aziridine-ring
cleavage. Carbohydr. Res. 2007, 342, 147–153; (g) Suzuki, K.; Hashimoto, H. Syn-
thesis of ethyl 2-acetamido-6-S-(5-amino-5-deoxy-β-D-arabinopyranosyl)-2-deoxy-1,6-
dithio-β-D-glucopyranoside: a sulfur-linked 5-amino-5-deoxyglycopyranosyl disaccha-
ride. Carbohydr. Res. 2000, 323, 14–17.
2. (a) Angelaud, R.; Landais, Y.; Parra-Rapado, L. Stereocontrolled access to
Carba-C-disaccharides via functionalized dienylsilanes. Tetrahedron Lett. 1997, 38,
8845–8848; (b) Bleriot, Y.; Giroult, A.; Mallet, J.-M.; Rodriguez, E.; Vogel, P.; Sinay, P.
Synthesis of seven- and eight-membered carbasugar analogs via ring-closing metathe-
sis and their inhibitory activities toward glycosidases. Tetrahedron Asymm. 2002, 13,
2553–2565; (c) Ferritto, R.; Vogel, P. Synthesis of an α-C-galactoside of a carbasugar: a
new class of disaccharide mimics. Tetrahedron Lett. 1995, 36, 3517–3518; (d) Mehta, G.;
Lakshminath, S.; Talukdar, P. A norbornyl route to aminocyclohexitols: syntheses of di-
verse aminocarbasugars and ‘confused’ aminocarbasugars. Tetrahedron Lett. 2002, 43,
335–338. (e) Frigell, J.; Cumpstey, I. First synthesis of 4a-carba-β-D-galactofuranose.
Tetrahedron Lett. 2007, 48, 9073–9076.
3. (a) Haines, A.H.; Carvalho, I. Synthesis of a novel pseudodisaccharide glycoside as
a potential glycosidase inhibitor. Chem. Commun. 1998, 817–818; (b) Ogawa, S.; Yokoi,
S.; Kimura, N.; Shibata, Y.; Chida, N. Synthesis of pseudo-trehaloses: [(1,2,4/3,5)-2,3,4-
trihydroxy-5-hydroxymethyl-1-cyclohexyl]-D-glucopyranosides. Carbohydr. Res. 1988,
181, 57–66; (c) Carvalho, I.; Haines, A.H. N-Linked carba-disaccharides as potential
inhibitors of glucosidases I and II. J. Chem. Soc. Perkin Trans. 1 1999, 1795–1800;
(d) Ble´riot, Y.; Dintinger, T.; Guillo, N.; Tellier, C. Synthesis of an amidine pseudo-
(1→6)-dimannoside and evaluation as a glycosidase inhibitor. Tetrahedron Lett. 1995,
36, 5175–5178; (e) Saotome, C.; Kanie, Y.; Kanie, O.; Wong, C.-H. Synthesis and en-
zymatic evaluation of five-membered iminocyclitols and a pseudodisaccharide. Bioorg.
Med. Chem. 2000, 8, 2249–2261.
4. Pe´rez, G.S.; Pe´rez, G.R.M.; Pe´rez, G.C.; Zavala, S.M.A.; Vargas, S.R. Coyolosa,
a new hypoglycemic from Acrocomia mexicana. Pharm. Acta Helv. 1997, 72, 105–
111.
5. (a) Haines, A.H. Evidence on the structure of Coyolosa. Synthesis of 6,6ꢁ-ether
linked hexoses. Tetrahedron Lett. 2004, 45, 835–837; (b) Haines, A.H. Synthesis of 6,6-
ether linked disaccharides from D-allose, D-galactose, D-glucose and D-mannose; evi-
dence on the structure of Coyolosa. Org. Bioorg. Chem. 2004, 2, 2352–2358.
6. Takahashi, H.; Fukuda, T.; Mitsuzuka, H.; Namme, R.; Miyamoto, H.; Ohkura, Y.;
Ikegami, S. Development of a novel sugar linkage: 6,6ꢁ-ether-connected sugars. Angew.
Chem. Int. Ed. 2003, 42, 5069–5071.
7. Akhtar, T.; Eriksson, L.; Cumpstey, I. Unusual synthesis of carbohydrate sec–sec
ether-linked pseudodisaccharides. Carbohydr. Res. 2008, 343, 2094–2100.
8. Takahashi, H.; Mitsuzuka, H.; Nishiyama, K.; Ikegami, S. A facile synthesis of
neosaccharides: 2,6ꢁ-and 3,6ꢁ-ether-linked sugars. Synthesis 2006, 1415–1418.
9. Scholl, M.; Ding, S.; Lee, C.W.; Grubbs, R.H. Synthesis and activity of a new gen-
eration of Ruthenium-based olefin metathesis catalysts coordinated with 1,3-dimesityl-
4,5-dihydroimidazol-2-ylidene ligands. Org. Lett. 1999, 1, 953–956.
10. Lam, S.N.; Gervay-Haque, J. Solution- and solid-phase oligosaccharide synthesis
using glucosyl iodides: a comparative study. Carbohydr. Res. 2002, 337, 1953–1965.

C. Mukherjee & A.K. Misra
482
11. Chambers, D.J.; Graham, R.E.; Fairbanks, A.J. An approach to the synthesis of
α-(1–6)-C-disaccharides by tandem Tebbe methylenation and Claisen rearrangement.
Tetrahedron 2005, 61, 7184–7192.
12. Belakhov, V.; Dovgolevsky, E.; Rabkin, E.; Shulami, S.; Shoham, Y.; Baasov, T. Syn-
thesis and evaluation of a mechanism-based inhibitor of KDO8P synthase. Carbohydr.
Res. 2004, 339, 385–392.
13. Kim, M.; Grzeszczyk, B.; Zamojski, A. Homologation of protected hexoses with
Grignard C1 reagents. Tetrahedron 2000, 56, 9319–9337.
14. Wang, W.; Zhang, Y.; Sollogoub, M.; Sinay¨, P. From glucose to cyclooctanic
carbaglucose: a new class of carbohydrate mimetics. Angew. Chem. Int. Ed. 2000, 39,
2466–2467.
15. Tatsuta, K.; Niwata, Y.; Umezawa, K.; Toshima, K.; Nakata, M. Total syntheses of
glucosidase inhibitors, cyclophellitols. Carbohydr. Res. 1991, 222, 189–203.
16. Boons, G.J.P.H.; Van DerMarel, G.A.; van Boom, J.H. A versatile and new highly
stereoselective approach to the synthesis of L-glycero-D-manno-heptopyranosides.
Tetrahedron Lett. 1989, 30, 229–232.
17. (a) Tarnk, T.M.; Grubbs, R.H. The development of L2×2Ru = CHR olefin metathe-
sis catalysts: an organometallic success story. Acc. Chem. Res. 2001, 34, 18–29;
(b) Grubbs, R.H.; Chang, S. Recent advances in olefin metathesis and its application in
organic synthesis. Tetrahedron 1998, 54, 4413–4696; (c) Chatterjee, A.K.; Morgan, J. P.;
Scholl, M.; Grubbs, R.H. Synthesis of functionalized olefins by cross and ring-closing
metatheses. J. Am. Chem. Soc. 2002, 122, 3783–3784.
18. Pearlman, W.M. Noble metal hydroxides on carbon nonpyrophoric dry catalysts.
Tetrahedron Lett. 1967, 8, 1663–1664.