Direct preparation of N-glycosidic bond-linked nonionic carbohydrate-based surfactant (NICBS) via ritter reaction

Article abstract of DOI:10.1002/ejoc.200700079

The Ritter reaction has been successfully extended to the direct preparation of N-glycosidic bond-linked nonionic carbohydrate-based surfactants from carbohydrates and nitriles in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) and silve

Full text of DOI:10.1002/ejoc.200700079

SHORT COMMUNICATION
DOI: 10.1002/ejoc.200700079
Direct Preparation of N-Glycosidic Bond-Linked Nonionic Carbohydrate-Based
Surfactant (NICBS) via Ritter Reaction
Zerong Daniel Wang,*[a] Samia O. Sheikh,[a] Shannon Cox,[a] Yulu Zhang,[a] and
Keegan Massey[a]
Dedicated to the memory of Professor Ramiro Sanchez
Keywords: Ritter reaction / Carbohydrates / Surfactants / Carbocations / Acylation
The Ritter reaction has been successfully extended to the di-
rect preparation of N-glycosidic bond-linked nonionic carbo-
hydrate-based surfactants from carbohydrates and nitriles in
the presence of trimethylsilyl trifluoromethanesulfonate
(TMSOTf) and silver perchlorate (AgClO4) on a high-speed
mechanical shaker. The new surfactant molecules have the
features of low toxicity, environmental compatibility and bio-
degradability.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Notably, N-acyl-N-methylglucamides (simplified as glucam-
ides, vide infra), the second largest used carbohydrate-based
surfactants, have found wide applications, mainly because
of their mildness,[12] stability, rinsability,[13] synergistic effect
with anionic surfactants,[14] and particularly their excellent
functions in foaming, thickening, emulsifying[12] and de-
greasing.[15] For example, glucamides have been applied as
sole surfactants[7c] or in combination with sodium dodecyl
sulfate (SDS) in toothpaste;[16] and are used in shampoo
and soap bar for foaming.[17] More importantly, due to
strong hydrogen bonding among hydrophilic headgroups,
glucamides have been applied to accelerate emulsion poly-
merization[18] and to prepare technical membranes,[12] espe-
cially the stable monolayers used for the solubilization of
membrane proteins from animal cells.[7d] Additionally, glu-
camides are readily biodegradable, as evidenced by 99% of
primary degradation and more than 98% of DOC removal
from the standard degradation test using a batch-activated
sludge system and the modified Sturm test.[19]
Introduction
Although polyethyleneglycol (PEG)[1] based nonionic
surfactants have found many applications in metal recov-
ery,[2] soil bioremediation,[3] preparation of nanosized par-
ticles,[4] and detergents (e.g., Triton X-100),[5] etc., nonionic
carbohydrate-based surfactants (NICBS) including alkyl
polyglycosides (APGs)[6] and N-acyl-N-methylglucamides[7]
have become increasingly important today. Such a trend is
possibly because PEG-type surfactants possess a cloud
point[8] and separate into two phases at somewhat elevated
temperature due to the dehydration of the hydrophilic
headgroup.[9] Other drawbacks of PEG-type surfactants in-
clude persisting environmental concerns, a forseeable short-
age originating from petrochemical resources,[10] and the
high solubility of APGs in lipophilic media which necessi-
tates large amounts of surfactant for solubilization, emulsi-
fication and detergency.[8] In contrast, NICBSs are sus-
tainably available, biocompatible, biodegradable[6a] and low
(or non-) toxic. In addition, they do not possess cloud
points because of the highly hydrophilic carbohydrate
headgroups.[8] The increasing demand for NICBSs are also
evidenced by the inauguration of a 23000 tons per annum
(tpa) production plant for APGs by the Henkel Corpora-
tion in USA in 1992, and Henkel KGaA in Germany in
1995 with equal production capacity of APGs,[6b] as well
as a 40000 tpa capacity for N-acyl-N-methylglucamides.[11]
Results and Discussion
Reported in this work is a new type of nonionic carbo-
hydrate-based surfactant, and its simple preparation
method. The new surfactant molecules have a β-N-glyco-
sidic bond connecting to a hydrophobic tail, and are quite
different from the known glucamide surfactants (Figure 1).
Conventionally, glucamide surfactants are usually prepared
from reductive amination of glucose and methylamine by
hydrogenation over Raney nickel,[20] followed by amidation
under the Schotten–Bauman condition,[21] so that the C1 of
the carbohydrate moiety is in an alcohol oxidation state
[a] Department of Chemistry, University of Houston-Clear Lake,
2700 Bay Area Boulevard, Houston, TX 77058, USA
Fax: +1-281-283-3795
E-mail: wang@uhcl.edu
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2007, 2243–2247
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2243

Z. D. Wang, S. O. Sheikh, S. Cox, Y. Zhang, K. Massey
SHORT COMMUNICATION
rather than an aldehyde oxidation state, and the carbo- HSQC spectrum, as shown in the supporting information
hydrate ring is opened after the amination.[20] In contrast, (for supporting information see also the footnote on the
the C1 of the carbohydrate moiety in our case is still in an first page of this paper).
aldehyde oxidation state with one proton on the nitrogen
atom.
Scheme 1. The preparation of N-acyl-1-deoxy-β-D-glucopyranosyl-
amines and their derivatives.
Such facile preparation of NICBS has the following fea-
tures. First, the reaction is carried out under mechanochem-
ical treatment that has been verified to accelerate reaction
Figure 1. The general structure of N-acyl-1-deoxyglucopyranosyla-
mines and glucamides.
rate.[26] Our results have shown that carbohydrates in the
solid state can be efficiently acylated to peresters of a single
We believe that the new surfactants would have similar configuration with good to high yields under mechanical
applications to those glucamides, and in some points, they force.[25] In this work, the mixture of carbohydrate,
are superior to those glucamides for the following reasons. TMSOTf and an excess of nitrile was vigorously vibrated
First, the new compounds are stable enough to be applied on a high-speed shaker at room temperature, and was
as surfactants, as indicated by the wide distribution of sim- worked-up after 7 to 24 h. However, the same reaction un-
ilar N-glycosidic bonds in glycopeptides,[22] glycoproteins[23] der magnetic stirring was remarkably slow. Comparing to
and nucleotides. Second, NICBSs should be more hydro- the mechanochemical force, microwave has also been widely
philic and, thus, form more stable micelles than glucamides applied in organic synthesis to accelerate chemical reac-
do. Greater hydrophilicity is expected because there is one tions.[27] One such example is the preparation of glycosyla-
more proton on the nitrogen atom of the amide bond in tion from Kochetkov amination under microwave irradia-
NICBS, which can participiate in hydrogen bonding as with tion at 40 °C, for which the reaction time has been short-
the peptide bonds of protein in forming β-sheet; whereas in ened from typically 5 d to only 90 min. By treatment of 2-
glucamides the hydrogen is replaced by a methyl group, and iminothiolane, Seeberger et al., have converted the resulting
the carbonyl group in such amido group might not be ac- glycosylamines into almidine derivatives[28] that are similar
cessible for hydrogen bonding due to the increased steric to but not exactly the same as our NICBSs with amido
hindrance. Moreover, even though the glucamides are read- linkage between the carbohydrate and the hydrocarbon tail.
ily biodegradable,[19] the new surfactant molecules should Second, even though protection and deprotection are usu-
be more benign to the environment because the amide link- ally required for most carbohydrate transformations,[29] the
age in our case is connected to a carbohydrate moiety via a carbohydrate was used directly in our case without any pro-
N-glycosidic bond, which is more labile for degradation tection. Regarding another feature of our preparation of
than a normal amide bond, as in peptides and glucamides. NICBSs, activation of the carbohydrate is not necessary,
In addition, the new molecules would have lower toxicity, although it is common that glycol donors are usually acti-
if any, than the glucamides, because the new surfactant vated by means of conversion into glycosyl halides,[30] sul-
molecules degrade into fatty acid and glucosylamine. In fides,[31] or trichloroacetimidates,[32] etc., then reacted with
comparison, the glucamides may be converted into fatty ac- glycol acceptors in the presence of a Lewis acid. Further-
ids and N-methylglucosylamine after degradation, and more, such a one-step reaction is facile but justifiable be-
methylamines are generally considered to be toxic.[24]
tween carbohydrates and nitriles. Although in many organic
We also report here a facile preparation of such surfac- reactions nitriles are applied as either solvents (e.g., acetoni-
tant molecules directly from carbohydrate and nitriles in the trile[33]) or electrophiles[34] to give compounds such as imid-
presence of a Lewis acid, under mechanical agitation from ates[33] or ketones,[34] there are also many examples in which
a high speed shaker,[25] as shown in Scheme 1. The resulting nitriles function as nucleophiles in the presence of even
molecules are then acetylated for the sake of structural stronger electrophiles (e.g., carbocations). Under these con-
characterization. The product can also be prepared directly ditions, carbocations have one empty p orbital, and the ni-
from β--glucose pentaacetate and nitrile under the same trogen atoms of nitriles have one pair of electrons, so that
reaction conditions. The presence of hydrogen on the N- the lone pair electrons can fill into the empty p orbital of
glycosidic linkage is clearly indicated from the combination the carbocations to form nitrilium cations. The resulting ni-
1
of H NMR, H-H COSY and H-C HSQC spectra, where trilium cations in the presence of water are converted into
the NH signal is not correlated to the carbon signal in the amides.[35] This type of reaction is generally referred to as
2244
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 2243–2247

Nonionic Carbohydrate-Based Surfactants
SHORT COMMUNICATION
Scheme 2. Possible mechanism for the formation of N-glycosidic surfactant.
a Ritter reaction,[35,36] and has been observed for alcohols tra. This is as would be expected being that carbohydrate
and olefins,[35] as well as trioxanes,[37] N-tosylazetidines,[38] in the presence of Lewis acid (e.g., TMSOTf) is converted
aziridines[36d] and epoxides.[36c]
into an oxonium cation, and nitrile adds to the oxonium
In addition, the Ritter reaction is not new for carbo- double bond preferably from the top of the carbohydrate
hydrate chemists either, though it has not been explored ring because of the blockage of 2-OH at the bottom of the
extensively. As an example, Hindsgaul et al., have applied ring, as shown in Scheme 2. Alternatively, the empty p or-
the Ritter reaction to the combinatorial synthesis of a small bital of the carbocation intermediate may partially share an
β-peptide library from three different ketoses and three dif- electron from the lone pair electrons of oxygen at the C2
ferent amines in the presence of a nitrile.[39] In fact, the position, and the other side of the p orbital is more elec-
formation of the nitrilium cation in carbohydrate chemistry tron-deficient, thus the nitrogen atom can approach from
has been noted as early as 1991 by Sinaÿ who rationalized the top of the ring, leading to the formation of β-N-glyco-
the β-selectivity for the glycosylation of thioglycosides in sidic bond. This result is consistent with the results of
acetonitrile in the presence of tris(4-bromophenyl)ammoni- Sinaÿ, Crich, as well as others where nitriles favor the β-
umyl hexachloroantimonate (TBPA·+), a stable radical cat- selectivity.[43] Additionally, like other Ritter reactions, the
ion that functions as a one-electron transfer reagent.[31d] Ritter reaction with carbohydrates can also take place in
Recently, Crich et al., have applied the Ritter reaction to the presence of TMSOTf without the addition of AgClO4.
enhance the β-selectivity of the -rhamnopyranosylation of However, the addition of AgClO4 generally gives a cleaner
thioglycosides by addition of 5% of acetonitrile or propio- reaction. Moreover, it should be pointed out that the Ritter
nitrile to the reaction solution, using 1-(phenylsulfinyl)pip- reaction is also competed with other side reactions involv-
eridine/trifluoromethanesulfonic anhydride as the pro- ing carbocations, such as the ring-enlargement of cyclic
moter.[40] In addition, even in the presence of such a little carbocations,[35c] the rearrangement of carbocations,[43] etc.
amount of acetonitrile or propionitrile in dichloromethane, The Ritter reaction of a carbohydrate having more than one
the competing Ritter reaction with the desired glycosylation OH group may lead to the formation of many carbocation
is still detectable, though the intermediate decomposes im- centers and give side products; however, often the acylam-
mediately. Our study probably is the second to actually iso- ino glycosides are isolated as major products. Finally, our
late the Ritter reaction product involving carbohydrate, reaction condition is very close to many reported glycosyla-
which indicates the feasibility of preparation of carbo- tions carried out in acetonitrile in the presence of TMSOTf
hydrate-containing nonionic surfactant molecules directly or other Lewis acids.[44] This study indicates the potential
from nitriles of long hydrocarbon tails and simple carbo- complication of glycosylation when carried out in acetoni-
hydrates without prior protection and activation. It is trile.
known that the outcome of the Ritter reaction depends on
the reactivity of nitriles as well as the stability of carbo-
cations,[42] thus tertiary alcohols give much higher yields
Conclusions
of Ritter products than primary or secondary alcohols.[41]
Similarly, in our reaction, C1 of the carbohydrate forms the
In conclusion, we report herein a new type of nonionic
most stable carbocation to react with nitrile. It is worth not- carbohydrate-based surfactant that holds many structural
ing that the electron-rich nitriles readily react with carbo- features of interest and is benign to the environment. Con-
hydrate, whereas electron-deficient nitriles (e.g., benzoni- currently, this type of surfactant molecule can be simply
trile) react poorly or do not react at all.
prepared by the Ritter reaction between carbohydrates and
Another feature of our study is that all the N-glycosidic nitriles of long hydrocarbon chain under mechanochemical
bonds are proven to be of β-configuration from NMR spec- force without prior protection and activation.
Eur. J. Org. Chem. 2007, 2243–2247
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2245

Z. D. Wang, S. O. Sheikh, S. Cox, Y. Zhang, K. Massey
SHORT COMMUNICATION
[10] G. Bognolo, Lipid Technol. Newsletter 1999, 5, 58–63.
[11] D. R. Karsa, Chem. Ind. 1998, 9, 685–691.
Experimental Section
[12] A. Lif, M. Hellsten, in Nonionic Surfactants: Organic Chemis-
try Surfactant Science Series, vol. 72 (Ed.: N. M. van Os), Mar-
cel Dekker, New York, 1998, pp. 177–200.
Typical Experimental Procedure: -Glucose (0.225 g, 1.25 mmol),
acetonitrile (10 mL, 191.5 mmol), AgClO4 (66 mg, 0.3 mmol), and
TMSOTf (d = 1.228 g/mL, 0.4 mL, 2.2 mmol) were added to an
18-mL scintillation vial. The vial was capped and mounted to the
high-speed shaker. After 3 h of vigorous vibration at room tem-
perature, solid glucose disappeared, and a rose or red purple solu-
tion formed. After 24 h, 0.5 mL of Et3N was added to quench the
reaction, and the mixture was directly loaded to a 10-cm silica gel
column and washed with hexane/EtOAc (2:1 to 1:1) to remove un-
reacted acetonitrile and Et3N, and then eluted with EtOAc/MeOH
(3:1). Upon evaporation, 0.237 g of viscous oil was obtained 85.8%
and the oil was directly acetylated with 2 mL of Ac2O in 2 mL of
pyridine. The reaction mixture was diluted with 50 mL of EtOAc
and washed with 1  HCl (3ϫ20 mL), saturated NaHCO3 aqueous
solution (2ϫ20 mL) and brine (20 mL), and dried with CaCl2. Af-
ter removal of solvent, the residue was purified by silica gel column
chromatography using hexane/EtOAc (5:1 to 3:2) to afford 0.113 g
of 1-acetamido-2,3,4,6-tetraacetyl-1-deoxy-β--glucopyranose, in
yield of 27.1%.
[13]
C. M. Bellemain, M. J. M. Giret, W. V. J. Richardson
(Procter & Gamble), WO Patent 96 03974, 1996.
P. D. T. Huibers, D. O. Shah, Langmuir 1997, 13, 5762–5765.
H. J. Scholz, “Aminozucker als Basischemikalien für neue Ten-
side”, Annual meeting of the Surfactant Division of the Ger-
man Chemical Society, Garmisch-Partenkirchen (Germany),
May 29–31, 1996.
W. Breitzke, K.-H. Gantke (Henkel KGaA), German Patent
4,406,746, 1995.
a) E. D. Brock, A. L. Larrabee (Procter & Gamble), WO Patent
92 05764, 1992; b) J. E. Kaleta, F. A. Pichardo (Procter &
Gamble), WO patent 92 13059, 1992.
[14]
[15]
[16]
[17]
[18]
[19]
[20]
A. Fischer, R. Vybiral (Hoechst AG), German Patent 4,237,434,
1994.
M. Stalmans, E. Matthijs, E. Weeg, S. Morris, SOFW J. 1993,
13, 10–13.
R. G. Laughlin, Y.-C. Fu, F. C. Wireko, J. J. Scheibel, R. L.
Munyon, in Novel Surfactants: Preparation, Application, and
Biodegradability, Surfactant Science Series, vol. 74 (Ed.: K.
Holmberg), Marcel Dekker, New York, 1998, pp. 2–30.
a) B. Strecker, H. Wolf, A. Oftring, H.-H. Bechtolsheimer, D.
Hertel (BASF AG), German Patent 4235783, 1994; b) D. S.
Connor, J. Kao, J. J. Scheibel, J. N. Kao (Procter & Gamble),
WO Patent 9206071, 1990.
a) V. Y. Dudkin, M. Orlova, X. D. Geng, M. Mandal, W. C.
Olson, S. J. Danishefsky, J. Am. Chem. Soc. 2004, 126, 9560–
9562; b) C. J. Bosques, S. M. Tschampel, R. J. Woods, B. Impe-
riali, J. Am. Chem. Soc. 2004, 126, 8421–8425.
Supporting Information (see footnote on the first page of this arti-
cle): Experimental procedures for other nitriles, the characteriza-
tion of synthesized molecules by both HRMS and NMR (1H
NMR, 13C NMR, H-H COSY and H-C HSQC).
[21]
[22]
Acknowledgments
The authors thank the Robert Welch Foundation (BC-1586) and
Faculty Research & Support Fund of University of Houston-Clear
Lake for their generous support. The authors also thank Mr.
Huanyi Chu, Professor Xiao-lian Gao and Dr. Youlin Xia at Uni-
versity of Houston for MS and NMR measurements.
[23]
[24]
R. Daniels, S. Svedine, D. N. Hebert, Cell Biochem. Biophys.
2004, 41, 113–137.
a) C. M. Westhoff, D. L. Siegel, C. G. Burd, J. K. Foskett, J.
Biol. Chem. 2004, 279, 17443–17448; b) M. E. Sanders, T. R.
Klaenhammer, J. Dairy Sci. 2001, 84, 319–331; c) E. Mekada,
T. Uchida, Y. Okada, J. Biol. Chem. 1981, 256, 1225–1227.
a) Z. Wang, United States Patents, July 13, 2006,
20060154846A1; b) Z. R. D. Wang, M. Matin, S. Sheikh, Mole-
cules 2005, 10, 1325–1334.
a) K. Komatsu, G. W. Wang, Y. Murata, T. Tanaka, K. Fuji-
wara, K. Yamamoto, M. Saunders, J. Org. Chem. 1998, 63,
9358–9366; b) J. Schmeyers, F. Toda, J. Boy, G. Kaupp, J.
Chem. Soc., Perkin Trans. 2 1998, 989–994; c) F. Toda, Acc.
Chem. Res. 1995, 28, 480–486; d) N. B. Singh, N. P. Singh, V. A.
Kumar, M. Nethaji, J. Chem. Soc., Perkin Trans. 2 1994, 361–
366; e) I. C. Paul, D. Y. Curtin, Acc. Chem. Res. 1973, 6, 217–
225.
[25]
[26]
[1] a) J. M. Harris, S. Zalipsky, Poly(ethylene glycol): Chemistry
and Biological Applications, American Chemical Society, Wash-
ington, D. C., 1997; b) V. M. Nace, Nonionic Surfactants: Po-
lyoxyalkylene Block Copolymers, Marcel Dekker, New York,
1996.
[2] T. Kinoshita, S. Akita, S. Ozacia, S. Nii, F. Kawaizumi, K.
Takahashi, J. Miner. Mater. Charact. Eng. 2003, 2, 71–82.
[3] a) N. Kosaric, Food Technol. Biotechnol. 2001, 29, 295–304; b)
C. C. R. Allen, D. R. Boyd, F. Hempenstall, M. J. Larkin,
N. D. Sharma, Appl. Environ. Microbiol. 1999, 65, 1335–1339;
c) Z. B. Liu, A. M. Jacobson, R. G. Luthy, Appl. Environ.
Microbiol. 1995, 61, 145–151.
[4] G. L. Li, G. H. Wang, Nanostruct. Mater. 1999, 11, 663–668.
[5] a) A. Musatov, J. Ortega-Lopez, N. C. Robinson, Biochemistry
2000, 39, 12996–13004; b) G. N. Williams, P. Hambright, Inorg.
Chem. 1978, 17, 2687–2688.
[6] a) W. von Rybinski, K. Hill in Novel Surfactants: Preparation,
Application, and Biodegradability, Surfactant Science Series,
vol. 74 (Ed.: K. Holmberg), Marcel Dekker, New York, 1998,
pp. 31–85; b) K. Hill, W. v. Rybinski, G. Stoll, Alkyl Polyglycos-
ides: Technology, Properties and Applications, VCH, Weinheim,
1997.
[27]
[28]
[29]
P. Lidström, J. Tierney, B. Wathey, J. Westman, Tetrahedron
2001, 57, 9225–9283.
M. A. Brun, M. D. Disney, P. H. Seeberger, ChemBioChem
2006, 7, 421–424.
a) Z. J. Witczak, K. Tatsuta, Carbohydrate Synthons in Natural
Products Chemistry: Synthesis Functionalization, and Applica-
tions, American Chemical Society, Washington, D. C. 2003; b)
T. K. Lindhorst, Essentials of Carbohydrate Chemistry and Bio-
chemistry, Wiley-VCH, Weinheim, 2002; c) S. Hanessian, Pre-
parative Carbohydrate Chemistry, Marcel Dekker, New York,
1997.
[30]
[31]
a) R. M. van Well, K. P. R. Kartha, R. A. Field, J. Carbohydr.
Chem. 2005, 24, 463–474; b) B. B. Snider, N. H. Vo, S. V.
O’Neil, J. Org. Chem. 1998, 63, 4732–4740; c) B. B. Snider,
N. H. Vo, S. V. O’Neil, B. M. Foxman, J. Am. Chem. Soc. 1996,
118, 7644–7645.
a) T. W. D. F. Rising, T. D. W. Claridge, N. Davies, D. P. Gam-
blin, J. W. B. Moir, A. J. Fairbanks, Carbohydr. Res. 2006, 341,
1574–1596; b) L. J. Wei, G. H. Wei, H. C. Zhang, P. G. Wang,
Y. G. D u , Carbohydr. Res. 2005, 340, 1583–1590; c) N. E. Ni-
[7] a) T. Yamaguchi, Pure Appl. Chem. 1999, 71, 1741–1751; b) B.
Fabry, German Patent, 1995, 4,400,632; c) B. Fabry, German
Patent 1995, 4,406,745; d) J. E. K. Hildreth, Biochem. J. 1982,
207, 363–366.
[8] K. Shinoda, A. Carlsson, B. Lindman, Adv. Colloid Interface
Sci. 1996, 64, 253–271.
[9] a) A. Afkhami, T. Madrakian, H. Siampour, J. Braz. Chem.
Soc. 2006, 17, 797–802; b) G. C. Kalur, S. R. Raghavan, J.
Phys. Chem. B 2005, 109, 8599–8604.
2246
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 2243–2247

Nonionic Carbohydrate-Based Surfactants
SHORT COMMUNICATION
fantiev, A. A. Sherman, O. N. Yudina, P. E. Cheshev, Y. E.
Tsvetkov, E. A. Khatuntseva, A. V. Kornilov, A. S. Shashkov,
Pure Appl. Chem. 2004, 76, 1705–1714; d) P. Sinaÿ, Pure Appl.
Chem. 1991, 63, 519–528.
[38] B. A. B. Prasad, A. Bisai, V. K. Singh, Org. Lett. 2004, 6, 4829–
4831.
[39] a) A. Lohse, F. Schweizer, O. Hindsgaul, Comb. Chem. High
Throughput Screening 2002, 5, 389–394; b) F. Schweizer, A.
Lohse, A. Otter, O. Hindsgaul, Synlett 2001, 1434–1436.
[40] D. Crich, M. Patel, Carbohydr. Res. 2006, 341, 1467–1475.
[41] S. Top, G. Jaouen, J. Org. Chem. 1981, 46, 78–82.
[42] a) D. Majumdar, G.-J. Boons in Handbook of Reagents for Or-
ganic Synthesis: Reagents for Glycoside, Nucleotide, and Peptide
Synthesis (Ed.: D. Crich), Wiley, Chichester, 2005, pp. 11–15;
b) J. Braccini, C. Derouet, J. Esnault, C. H. de Penhoat, J. M.
Mallet, V. Michon, P. Sinaÿ, Carbohydr. Res. 1993, 246, 23–41;
c) A. J. Ratcliffe, B. Fraser-Reid, J. Chem. Soc., Perkin Trans.
1 1990, 747–750; d) R. R. Schmidt, M. Behrendt, A. Toepfer,
Synlett 1990, 694–696; e) J. R. Pougny, P. Sinaÿ, Tetrahedron
Lett. 1976, 17, 4073–4076.
[32] a) A. Rencurosi, L. Lay, G. Russo, E. Caneva, L. Poletti, J.
Org. Chem. 2005, 70, 7765–7768; b) L. Gandolfi-Donadio, C.
Gallo-Rodriguez, R. M. de Lederkremer, J. Org. Chem. 2002,
67, 4430–4435.
[33] a) M. H. Zhong, I. Nowak, M. J. Robins, J. Org. Chem. 2006,
71, 7773–7779; b) R. G. Syvret, K. M. Butt, T. P. Nguyen, V. L.
Bulleck, R. D. Rieth, J. Org. Chem. 2002, 67, 4487–4493; c) V.
Martichonok, G. M. Whitesides, J. Am. Chem. Soc. 1996, 118,
8187–8191.
[34] G. A. Molander, C. N. Wolfe, J. Org. Chem. 1998, 63, 9031–
9036.
[35] a) M. G. Rosenberg, U. Haslinger, U. H. Brinker, J. Org. Chem.
2002, 67, 450–456; b) F. Cacace, G. Ciranni, P. Giacomello, J.
Am. Chem. Soc. 1982, 104, 2258–2261; c) T. Sasaki, S. Eguchi,
T. Ishii, J. Org. Chem. 1970, 35, 2257–2263.
[36] a) Z. Wang, Comprehensive Organic Named Reactions, with De-
tailed Mechanism Discussions and Updated Experimental Pro-
cedures, John Wiley & Sons, Inc. in press; b) T. Maki, K. Ishih-
ara, H. Yamamoto, Org. Lett. 2006, 8, 1431–1434; c) J. M.
Concellón, J. R. Suárez, V. del Solar, J. Org. Chem. 2005, 70,
7447–7450; d) J. M. Concellón, E. Riego, J. R. Suárez, S.
García-Granda, M. R. Díaz, Org. Lett. 2004, 6, 4499–4501; e)
S. S. Koval’skaya, N. G. Kozlov, E. A. Dikusar, Russ. J. Gen.
Chem. 2004, 74, 897–902; f) T.-L. Ho, R.-J. Chein, J. Org.
Chem. 2004, 69, 591–592.
[43] S. Edwards, F.-H. Marquardt, J. Org. Chem. 1974, 39, 1963–
1965.
[44] a) M. Adinolfi, A. Iadonisi, A. Ravidà, M. Schiattarella, J.
Org. Chem. 2005, 70, 5316–5319; b) M. H. Zhong, I. Nowak,
M. J. Robins, Org. Lett. 2005, 7, 4601–4603; c) A. Kanai, T.
Kamino, K. Kuramochi, S. Kobayashi, Org. Lett. 2003, 5,
2837–2839; d) I. Braccini, C. Derouet, J. Esnault, C.
Hervé de Penhoat, J.-M. Mallet, V. Michon, P. Sinaÿ, Car-
bohydr. Res. 1993, 246, 23–41; e) A. Marra, J. Esnault, A. Vey-
rières, P. Sinaÿ, J. Am. Chem. Soc. 1992, 114, 6354–6360; f)
A. J. Ratcliffe, B. Fraser-Reid, J. Chem. Soc., Perkin Trans. 1
1990, 747–750.
Received: January 30, 2007
Published Online: March 14, 2007
[37] N. Ogata, K. Saito, J. Polym. Sci., Polym. Chem. Ed. 1975, 13,
2763–2773.
Eur. J. Org. Chem. 2007, 2243–2247
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2247