Versatile sugar derivatives for the synthesis of potential degradable hydrophilic-hydrophobic polyurethanes and polyureas

Article abstract of DOI:10.1080/07328300802030878

Biodegradable polymers obtained from renewable natural sources are currently receiving increasing attention because they are an alternative to the traditional petroleum-based plastics. In the present communication we describe the synthesis of the diol mon

Full text of DOI:10.1080/07328300802030878

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Versatile Sugar Derivatives for the
Synthesis of Potential Degradable
Hydrophilic‐Hydrophobic Polyurethanes and
Polyureas
M. Violante de Paz Ba´ñez a , Jose´ A. Aznar Moreno a & Juan A. Galbis a
a Department of Organic and Pharmaceutical Chemistry, Faculty of
Pharmacy , University of Seville , Seville, Spain
Published online: 28 May 2008.
To cite this article: M. Violante de Paz Ba´ñez , Jose´ A. Aznar Moreno & Juan A. Galbis (2008) Versatile
Sugar Derivatives for the Synthesis of Potential Degradable Hydrophilic‐Hydrophobic Polyurethanes and
Polyureas, Journal of Carbohydrate Chemistry, 27:2, 120-140, DOI: 10.1080/07328300802030878
To link to this article: http://dx.doi.org/10.1080/07328300802030878
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Journal of Carbohydrate Chemistry, 27:120–140, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0732-8303 print 1532-2327 online
DOI: 10.1080/07328300802030878
Versatile Sugar Derivatives
for the Synthesis of Potential
Degradable Hydrophilic-
Hydrophobic Polyurethanes
and Polyureas
´
´
M. Violante de Paz Ban˜ez, Jose A. Aznar Moreno,
and Juan A. Galbis
Department of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy,
University of Seville, Seville, Spain
Biodegradable polymers obtained from renewable natural sources are currently receiving
increasing attention because they are an alternative to the traditional petroleum-based
plastics. In the present communication we describe the synthesis of the diol monomers
2,3,4-tri-O-benzyl-L-arabinitol (ABnOH) and 2,3,4-tri-O-benzylxylitol (XBnOH), and the
diamino monomers 1,5-diamino-1,5-dideoxy-2,3,4-tri-O-benzyl-L-arabinitol (ABnNH2)
and 1,5-diamino-1,5-dideoxy-2,3,4-tri-O-benzylxylitol (XBnNH2), which can be used in
the preparation of new potentially biodegradable sugar-based polymers. As an example,
we describe the synthesis and characterization of a polyurethane [PU-(ABnOH-HMDI)]
and a polyurea [PUR-(ABnNH2-HMDI)] by poly addition reaction of ABnOH and
ABnNH2 with 1,6-hexamethylene diisocyanate.
Keywords Polyurethanes, Polyureas, Biodegradable polymers, O-Benzylalditols,
Diaminosugars
Received January 10, 2008; accepted February 8, 2008.
Address correspondence to Juan A. Galbis, Department of Organic and Pharmaceutical
Chemistry, Faculty of Pharmacy, University of Seville, 41071 Seville, Spain. E-mail:
jgalbis@us.es
120

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
121
INTRODUCTION
The ever-increasing diversity of industrial activity is responsible for the
discharge of compounds that are toxic or difficult to degrade into the
environment.[1] Carbohydrates and vegetable oils are considered replace-
ments for some petroleum-based polymer precursors. The use of renewable
resources (mainly carbohydrates) in rigid polyurethane and polyurea
foams is known to offer several advantages, such as increased strength,
improved flame resistance, and enhanced biodegradability.[2,3] A review
of the preparation of polyurethanes using natural resources has been
provided.[4]
Such polyurethanes are produced as branched and cross-linked materials
by combining petroleum-based isocyanate reactants with polyols derived
from resources such as plant oils, carbohydrates, wood/lignin, cashew, and
cork. Depending on the procedure used to derive them from natural resources,
polyols with tunable hydroxyl content can be produced. Bio-based poly-
urethanes are materials ranging from flexible to rigid, and are thus able to
complete with commercially available polyurethanes made from petroleum-
based products. Bio-based polyurethane composites are also of interest, since
the addition of fibers such as glass or natural lignocellulose (e.g., hemp, jute,
flax) may result in improved thermo-mechanical properties. When natural lig-
nocellulose fibers are used, formation of covalent bonds between the fiber and
the isocyanate component is possible, with improved interaction between the
matrix and the fiber.
Few examples of linear sugar-based polyurethanes are described in the lit-
erature. The 2,5-diamino-2,5-dideoxy-1:4,3:6-dianhydrohexitol dihydrochlor-
ides with D-gluco, L-ido, and D-manno configurations were prepared by
Thiem et al. according to known procedures. They developed an initial
approach to novel polyurethanes by interfacial polycondensation of these
diamino monomers, as well as aliphatic diamines, with the bis(chloroformate)
derived from 1,4:3,6-dianhydro-D-sorbitol.[5,6] Catalytic polyaddition of the
monomer 2-deoxy-1,4:3,6-dianhydro-2-isocyanato-L-iditol gave the correspond-
ing AB-type polyurethane. A second route required the synthesis of the 2-azido-
5-O-chloroformyl-1,2-dideoxy-1,4:3,6-dianhydro-L-iditol, which underwent
spontaneous polycondensation by catalytic hydrogenation through the
2-amino-5-O-chloroformyl derivative.[7] The 2,5-diamino-2,5-dideoxy-1:4,3:6-
dianhydrohexitols with D-gluco, L-ido, and D-manno configurations was also
transformed into the corresponding diisocyanates by reaction with
phosgene.[8] The dithiodiisocyanato derivative was prepared from the
diamino-dianhydro-L-ido-hexitol and thiophosgene. Polyurethanes and polyur-
eas were synthesized from the D-gluco, D-manno, and L-ido monomers, and
poly(thio)urethanes and poly(thio)ureas from the corresponding L-ido
monomer.[8] Several modified D-glycosylamine and D-glucosamine monomers

´
M. V. de P. Ban˜ez et al.
122
were also synthesized by Thiem et al. to carry out catalytic polymerizations
leading to polymers with urea and urethane linkages.[9] Garcon et al.[10]
have reported the synthesis of two new polyurethanes accomplished by
reaction of 1,6-hexamethylene diisocyanate (HMDI) with methyl 2,6-di-O-
pivaloyl-a-D-glucopyranoside or methyl 4,6-O-benzylidene-a-D-glucopyrano-
side, catalyzed by 1,4-diazabicyclo[2.2.2]octane.
For polyurethane production, Donnelly[11] has carried out the synthesis of
copolyurethanes based on mixtures of commercial poly(THF diol)s with
glucose. Complex products resulted, which can be represented by mono- or
bis(glucoside) structures. From a variety of polyol blends, solid polyurethanes
were prepared, which ranged from linear, soluble, weak elastomers to
polymers of higher transition temperature and stiffness, low solubility, and
low extension under tensile load.[12] These effects are attributable to the
rigidity of the glucose unit, which also increases hydrogen bonding and poten-
tial for cross-linking. Polymers prepared with the higher levels of the gluco-
side are able to absorb significant amounts of water, suggesting uses in the
biological field.
Polyurethane-polyureas have been prepared using carbohydrates and
proteins from biomass.[13] Polyisocyanates (e.g., HMDI) reacted with carbo-
hydrate- and protein-containing biomass (e.g., from baker’s yeast) and, option-
ally, polyols in solution in dimethylsulfoxide (DMSO) or N,N-dimethyl
acetamide (DMA) at .1208C to give polyurethane-polyureas that are useful as
films, foams, etc. Pectin and related carbohydrates have also been used for the
preparation of polyurethane foams.[14]
The synthesis of polyurethane resins derived from polyoxyalkylated
arylated carbohydrates was achieved by Prahl and Hart.[15] First, a polyether
sugar was prepared by treating an arylated sugar with an alkylene oxide. The
polyether was then allowed to react with diisocyanates (such as tolylene diiso-
cyanate) to form polyurethane foams, which have low density, low thermal con-
ditions, and high strength and rigidity.
The preparation and applications of polyurethanes are recorded in
many patents and some papers; most of the polyurethanes are used as com-
modity materials and/or have industrial applications,[16,17] and some of
them are biodegradable and/or biocompatible materials.[18– 21] Therefore,
the biomedical field is one of the areas of greatest interest for their poten-
tial applications. The low toxicity, potential biodegradability, biocompatibil-
ity,[22] and versatile structures of polyurethanes make them suitable as part
[23,24]
of drug administration systems,
dermatological dressings,[25,26] and
hemocompatible materials for catheters (presenting
a
considerable
reduction in their thrombogenic character compared with uncoated poly-
urethane catheters[27]), and as filters and in biomedical instrumentation
and devices.[28–30]

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
123
RESULTS AND DISCUSSION
Synthesis and Characterization of the Monomers
The synthesis of the diol monomers 2,3,4-tri-O-benzyl-L-arabinitol
(ABnOH, 4a) and 2,3,4-tri-O-benzylxylitol (XBnOH, 4b) and diamino mono-
mers 1,5-diamino-1,5-dideoxy-2,3,4-tri-O-benzyl-L-arabinitol (ABnNH2, 6a)
and 1,5-diamino-1,5-dideoxy-2,3,4-tri-O-benzylxylitol (XBnNH2, 6b) was
accomplished following the synthetic Scheme 1.
The 1H NMR and 13C NMR spectra of the different compounds and
polymers (polyurethanes and polyureas) were elucidated with the aid of
other NMR experiments, such as COSY, DEPT, heteronuclear correlation, etc.
In the present study, the naturally occurring aldopentoses L-arabinose and
D-xylose have been selected for several reasons. Firstly, they are natural,
cheap, commercially available carbohydrates. Secondly, the reduction of their
hemiacetal derivatives 3a and 3b will lead to the diols 4a and 4b, respectively,
which differ only in the absolute configuration on one stereocenter. This par-
ticular feature could have important consequences in the physical properties
(crystallinity, solubility, stiffness, degradability, etc.) of their polymeric-based
materials synthesized.
There have been some attempts at using copolyurethanes and/or polyureas
as drug delivery systems, for encapsulating or embedding pharmaceuticals.[31]
In every case, the drug is anchored to the polymer by physical interactions. In
the present work, we have chosen benzyl ethers as protecting groups in the
carbohydrate-based monomers, in order to be orthogonally cleaved later.
Scheme 1: (a): NaH, BnBr, DMF, rt; (b) HCl 4M-acetonitrile, 16:10 v/v, 808C; (c) LiAlH4, THF, rt;
(d) Ph3P, DEAD, DPPA, THF, rt; (e) H2 2 p.s.i., C/Pd 10%, CH3OH, rt.

´
M. V. de P. Ban˜ez et al.
124
Therefore, the synthesized polyurethanes and polyureas could become amphi-
philic materials after hydrogenolysis, which would give them some special
properties. It is noteworthy that the presence of free hydroxyl groups in the
polymeric chains would allow the chemical anchoring of pharmacological com-
pounds of interest for therapeutic applications.
The preparation of benzyl-b,L-arabinopyranoside (1a) and benzyl-a,D-xylo-
pyranoside (1b) from the naturally occurring L-arabinose and D-xylose has pre-
viously been described in detail.[26] The protection of the hydroxyl groups of 1a
and 1b was carried out using sodium hydride and benzyl bromide in dry N,N-
dimethylformamide (DMF), to generate the tetra-O-benzyl derivative 2a and
2b in excellent yields (.85%). The preparation of the hemiacetals 3a and 3b
was achieved in acid media (acetonitrile-hydrochloric acid mixtures) at 808C.
The hydrolysis of the benzyl acetals 2a and 2b requires their solubilization
in the reaction mixture. Hence, the use of acetonitrile as a cosolvent was
crucial in this step. The reduction of 3a and 3b with a 1-M solution of
LiAlH4 in THF was accomplished in less than 2 h, at rt, with almost quantitat-
ive yields for the diol monomers 2,3,4-tri-O-benzyl-L-arabinitol (ABnOH, 4a)
and 2,3,4-tri-O-benzylxylitol (XBnOH, 4b). As expected, small differences in
their structures led to different physical properties. Thus, for example, the
diol 4a was isolated as a white solid and the diol 4b as an uncolored oil at rt.
The transformation of the diol 4a into the diamine monomer 6a was
attempted first using the classical methodology.[32] The procedure (Sch. 2)
involves the synthesis of the dimesyl derivative 7 (mesyl chloride, TEA, dichlor-
omethane, from 08C to rt) and subsequent displacement of the mesyl groups with
azide ion to give the compound 5a. The synthesis of 7 was achieved in good yield
(78%), but the subsequent displacement was not successful. The main product of
the reaction was the tetrahydrofuran derivative 8, in 44% overall yield. The
diazide derivative 5a was also isolated as a secondary product. Compound 8
can be of interest in various applications. For example, its template has been
incorporated in the structure of some substituted sulfonylaminopyrimidines
(rac-5-isopropyl-N-[5-(2-methoxyphenoxy)-2-(4-pyridyl)-6-(tetrahydrofuran-2-
ylmethoxy)-4-pyrimidinyl]-2-pyridinesulfonamide) for use as active ingredients
in pharmaceutical compounds, especially endothelin receptor antagonists.[33]
For the formation of the tetrahydrofuran derivative 8, it was necessary to
eliminate the benzyl and mesylate groups, by attack of the O-benzyl group on
C-4 to C-1. This was not surprising, as this type of elimination product has
Scheme 2: (f): MsCl, TEA, CH2Cl2, 0–208C; (g): NaN3, CH3CN-H2O 10:1, 808C.

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
125
Table 1: Coupling constants (JH,H) and torsion angles (fH,H) for 8-E1.
a
b
c
d
Compound
H,H
JH,H
fH,H
fH,H
fH,H
2,3
3.3
4.5
1.3
4.5
117
233
87
129
222
87
157
240
83
3,4
4,5R
4,5S
–49
–35
–37
aMeasured directly from the spectrum.
bCalculated from the Durette and Horton equation.[34]
cCalculated from the Altona equation.[35]
dTaken from models of the ideal conformation.[36]
already been reported by our group,[32] where the cleaved groups were a methyl
and a mesylate moiety. We obtained the all-trans derivative 8, in the preferen-
tial E1 conformation. This structure was deduced on the basis of the torsion
angles calculated from the coupling constants in agreement with modified
Karplus equations (Table 1).[34–36] The fact that the only tetrahydrofuran-
based product isolated in this reaction was the compound 8 suggests that the
cyclization mechanism is regioselective, in agreement with earlier
observations.[32,37]
Alternatively, the diazido derivatives 5a and 5b have been prepared from
the diols ABnOH (4a) and XBnOH (4b), in one step, by reaction with triphenyl-
phosphine, diethylazodicarboxylate (DEAD), and diphenylphosphoryl azide
(DPPA) in THF, at rt, with excellent yields (96% and 89%, respectively). The
formation of cyclic compounds was totally prevented by this method. The
reduction of the azide groups for the synthesis of the diamines ABnNH2 (6a)
and XBnNH2 (6b) was selectively carried out by hydrogenolysis in the
presence of the benzyl groups (H2, 2 p.s.i., Pd/C, 10%), without side reactions,
with almost quantitative yields (.92%).
Synthesis and Characterization of the Polymers
The polymerization reactions were almost quantitative. The polyurethane
(PU-ABnOH-HMDI) synthesized from 1,6-hexamethylene diisocyanate and
2,3,4-tri-O-benzyl-L-arabinitol was a white solid. The polyurea (PUR-ABnNH2-
HMDI) synthesized from the same diisocyanate was obtained as a pale yellow
solid. As the sugar monomer lacks a C2 symmetry axis, the resultant polymers
are nonregioregular (Scheme 3).[38]
The polyurethane presented a weight average molecular weight (MW) of
52,100. This value is of the order of those obtained by us from O-methyl-
protected xylitol, L-arabinitol, and threitol,[39] and markedly higher than
those of other sugar-based polyurethanes reported in the literature.[5–10] The

´
M. V. de P. Ban˜ez et al.
126
Scheme 3
Mw of the polyurea (4100) was lower than that of the polyurethane, probably
due to the insolubility of the former in the reaction solvent.
The chromatograms from GPC show monomodal curves in every case, and
hence, the polymerization process courses uniformly throughout the reaction
time and without side reactions. The reactions were allowed to proceed for a
short period of time—2 h for polyurethane and 1 h for polyurea—and the
unreacted terminal isocyanate groups were deactivated by the addition of tert-
butanolor1-decaneamine,respectively, preventingundesirablecross-linkedreac-
tions involving the isocyanate group.[40–42] As a consequence, the polyurethane is
soluble in common organic solvents such as chloroform or THF. In contrast, the
polyurea—showing a greater tendency to form hydrogen bonds with its own or
other polymer chains—presents reduced solubility in organic solvents, being
only slightly soluble in N-methylpyrrolidone and dimethylsulfoxide.
When the NMR characterization of the polymeric materials was carried
1
out, it was observed that the peaks of the H NMR spectra were broad and
the multiplicity was not always well resolved (Fig. 1).
Due to the presence of the N-H group in the backbone of the polymer chain,
these materials have a high tendency to bond to protic solvents. For this reason,
despite the long drying periods employed, some of the samples contain a residual
amount of solvent (,2.9% w/w).
The thermal analysis of the new polyurethane showed that it was very stable
to thermal degradation, having a decomposition onset temperature with a 10%
weight loss (8Td 10%) of 3198C. The new polymer tended to be more stable to
thermal degradation than its methoxylated counterpart.[39] The degradation
under nitrogen atmosphere proceeded in two steps—one with the main weight
loss at 3608C (weight loss .96%), and the second at 4568C, with a weight loss
of less than 2%.
The DSC studies of PU-ABnOH-HMDI showed a low Tg (368C), and a post
annealing Tm of 818C (Table 2). This semi-crystalline behavior contrasts with
that of the analogous methoxylated polymer (PU-AMeOH-HMDI), which

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
127
Figure 1: NMR spectra of polyurethane PU-ABnOH-HMDI in CDCl3. A:1H NMR spectrum; B: 13
C
NMR spectrum.
turned out to be amorphous.[39] The polyurea PUR-ABnNH2-HMDI showed
more crystallinity than the polyurethane. It presented a higher melting point
(1788C) and higher melting enthalpy (61 J/g). Its thermal degradation took
place via a very different pathway to that of the polyurethane, showing
thermal decomposition in several steps (Table 2).
Some attempts have been made at debenzylation of the polyurethane. We
obtained a high degree of deprotection (67%) by a general hydrogenation

Table 2: Thermal properties and molecular weights of the described polymers.
DSC
TGA
GPC
d
Tma
(8C)
DHma
(J/g)
Tgb
(8C)
Tmc
(8C)
DHmc
(J/g)
Tdon
DWf
(%)
Mwg
(g/mol)
Mng
(g/mol)
Polymer
(8C)
Te (8C)
PU-(ABnOH-
HMDI)
PUR-(ABnNH2-
HMDI)
69
12
59
36
81
8
319
253
360/
456
292/
96/2
59100
4100
29200
3800
175
108
178
61
45/41/1
352/437
aMeasured in the first heating cycle.
bMeasured in the second heating cycle, after rapid cooling to rt.
cMeasured after annealing for 1.5 h at 108C above Tg.
dOnset decomposition temperature (10% of weight lost).
eDecomposition temperatures measured at the peaks of the derivative curves; major peak in bold.
fWeight lost at the respective decomposition step.
gDetermined by GPC against polystyrene standards, with NMP as mobile phase.

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
129
procedure (C/Pd 10%, as catalyst, under hydrogen atmosphere [40 p.s.i.] at rt).
The key point was the solubilization of the polymeric material, in order to allow
the approach of the catalyst to the reaction centers in the polymers. The best
results were obtained with 8:4:1 mixtures of chloroform-THF-trifluoroacetic
acid. The degree of debenzylation was determined by 1H NMR.
We can conclude that the new O-benzyl-alditols and -diamino-alditols are
suitable monomers for the preparation of new potentially biodegradable poly-
urethanes and polyureas, as well as other polymers such as polyesters or polya-
mides. As the O-protecting groups are removable by hydrogenolysis, the new
polymers can be transformed into partially or fully hydroxylated polymers with
a controlled balance between their hydrophilic and hydrophobic properties.
EXPERIMENTAL
General Methods
Common reagents and solvents were purchased from Aldrich Chemical Co.
and used as received. Solvents were dried and purified, when necessary, by
appropriate standard procedures. Benzyl-b,L-arabinopyranoside (1a) and
benzyl a,D-xylopyranoside (1b) were prepared from the naturally occurring
L-arabinose and D-xylose by the classical Fischer and Beensch glycoside
synthesis.[43]
Optical rotations were measured in a Perkin-Elmer 341 polarimeter
20 + 58C (1 dm cell). Elemental analyses were determined in the Microana-
lyses Laboratories of the CITIUS Service, in the Universidad de Sevilla. IR
spectra (films or KBr discs) were recorded with a JASCO FT/IR-410 spec-
trometer. NMR spectra were recorded at 300 K on either a Bruker Advance
AV-500 or a Bruker AMX-500. Chemical shifts (d) are reported as parts per
million downfield from Me4Si. Mass spectra were obtained using a Kratos
MS80RFA instrument. Gel permeation chromatography (GPC) analyses were
performed using a Waters apparatus equipped with a Waters 2414 refractive
index detector and two Styragelw HR columns (7.8 ꢀ 300 mm) linked in
series, thermostatted at 608C, using N-methylpyrrolidone (NMP) as the
mobile phase, at a flow rate of 0.5 mL/min21. Molecular weights were
estimated against polystyrene standards. The thermal behavior of the poly-
urethanes and polyureas was examined by DSC, using a Perkin-Elmer DSC-7
calibrated with indium. DSC data were obtained from samples of 4 to 6 mg at
heating/cooling rates of 108C/min21 under a nitrogen flow. The glass
transition temperatures were determined at a heating rate of 208C min21 from
rapidly melt-quenched polymer samples. Thermogravimetric analyses (TGAs)
were performed under nitrogen atmosphere (flow rate 100 mL/min21) with a
Universal V4.3A TA Instrument at a heating rate of 108C/min21
.

´
M. V. de P. Ban˜ez et al.
130
The polymerization reactions were performed using standard Schlenk
techniques, in absence of humidity, under inert atmosphere. All glassware
was heated overnight at 808C before use, and was further heated under
vacuum to eliminate the surface moisture after assembly. The diol monomer
(Sch. 1) 2,3,4-tri-O-benzyl-L-arabinitol (ABnOH, 4a) and diamino monomer
1,5-diamino-1,5-dideoxy-2,3,4-tri-O-benzyl-L-arabinitol (ABnNH2, 6a), were
dried under high vacuum for at least 3 d. 1,6-Hexamethylene diisocyanate
(HMDI) was stored at 48C and handled under inert atmosphere. Anhydrous
tetrahydrofuran (THF) and N,N-dimethylacetamide (DMA) polymerization
solvents were further dried in order to eliminate residual water. THF was
refluxed in the presence of sodium, with benzophenone as indicator, and was
freshly distilled prior to use. DMA was vacuum distilled, and stored over mol-
ecular sieve in a desiccator for not more than a week before use. The other reac-
tants and reagents for the polymerizations were stored in a desiccator under
inert atmosphere until required.
Benzyl 2,3,4-tri-O-benzyl-b-L-arabinopyranoside (2a)
To sodium hydride (60% w/w) (0.96 g, 24 mmol) washed with dry pentane
(20 mL ꢀ 3) under argon atmosphere, a solution of 1a (1.44 g, 6 mmol) in dry
DMF (15 mL) was added dropwise with stirring at 08C. The mixture was
stirred at this temperature for 1 h, and then benzyl bromide (2.7 mL,
21.6 mmol) was added, and stirring was continued at rt overnight. Methanol
(2 mL) was added dropwise, and the mixture was stirred for 1 h. The reaction
mixture was evaporated to dryness and the residue was then dissolved with a
mixture of CHCl3 (50 mL) and aq NaHCO3 satd solution (20 mL). The organic
phase was washed with brine (10 mL) and then water (20 mL), dried (anhydrous
MgSO4), and concentrated. The yellowish residue was purified by column
chromatography (1:8 tert-butylmethyl ether-hexane, Rf ¼ 0.21) to give the
title compound as a white solid (2.8 g, 92%); m.p. 61.4–62.58; [a]D þ 131 (c 1.0,
dichloromethane); IR (cm21): 3062, 3029 (Ph), 1096 (C-O-CH2Ph) 738, 696
1
(Ph); H NMR (CDCl3, 200 MHz): d (ppm) 7.35 (m, 20H, 4 Ph), 4.93 (d, 1H,
H-1, J1,2 ¼ 3.2 Hz), 4.79 (1H, d, CHAHB-O-Ph, JHA,HB ¼ 11.9 Hz), 4.77 (1H, d,
CHCHD-O-Ph, JHC,HD ¼ 11.8 Hz), 4.75 (1H, d, CHEHF-O-Ph, JHE,HF
¼
12.4 Hz), 4.73 (2H, s, CHGHH-O-Ph), 4.66 (1H, d, CHCHD-O-Ph), 4.61 (1H, d,
CHAHB-O-Ph), 4.57 (1H, d, CHEHF-O-Ph), 4.04 (1H, dd, H-2, J2,3 ¼ 9.7 Hz),
3.95 (1H, dd, H-3, J3,4 ¼ 2.9 Hz), 3.80 (1H, m, H-4), 3.70 (2H, d, H-5A, H-5B,
J4,5A ¼ J4,5B ¼ 1.99 Hz); 13C NMR (CDCl3, 50 MHz): d (ppm) 138.74, 138.65,
138.28, 137.36 (4C, Ph), 128.27, 127.84, 127.72, 127.55 (20C, Ph), 96.54 (C-1),
77.28 (C-3), 76.34 (C-2), 73.85 (C-4), 73.29, 72.69, 71.62, 68.92 (4C, OCH2Ph)
60.41 (C-5); MS (CI): m/z 510 (M)þ, 509 (M-1)þ, 419 (M-CH2Ph)þ, 403
(M-OCH2Ph)þ, 181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
Anal. Calcd for C33H34O5: C, 77.62; H, 6.71. Found: C, 77.47; H, 6.53.

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
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Benzyl 2,3,4-tri-O-benzyl-a-D-xylopyranoside (2b)
This was obtained from 1b as an oil (85% yield), following the procedure
described above for 2a. [a]D þ 598 (c 1.7, dichloromethane); IR (cm21): 3063,
1
3028 (Ph), 1074 (C-O-CH2Ph) 734, 696 (Ph); H NMR (CDCl3, 500 MHz): d
(ppm) 7.32 (m, 20H, 4 Ph), 4.97 (1H, d, CHAHB-O-Ph, JHA,HB ¼ 11.0 Hz), 4.90
(1H, d, CHAHB-O-Ph), 4.79 (1H, d, H-1, J1,2 ¼ 3.6 Hz), 4.78 (1H, d, CHCHD-
O-Ph, JHC,HD ¼ 10.5 Hz), 4.76 (1H, d, CHCHD-O-Ph), 4.71 (1H, d, CHEHF-O-
Ph, JHE,HF ¼ 11.9 Hz), 4.66 (1H, d, CHEHF-O-Ph), 4.58 (1H, d, CHGHI-O-Ph,
JHG,HI ¼ 12.1 Hz), 4.54 (1H, d, CHGHI-O-Ph), 4.00 (dd, 1H, H-3,
J2,3 ¼ 9.6 Hz, J3,4 ¼ 8.0 H,), 3.65 (2H, m, H-5A/5B), 3.60 (1H, m, H-4), 3.48
(1H, dd, H-2); 13C NMR (CDCl3, 50 MHz): d (ppm) 139.01, 138.40, 138.31,
137.23 (4C, Ph), 128.46, 128.42, 128.40, 128.33, 128.25, 127.99, 127.94,
127.86, 127.84, 127.81, 127.78, 127.76, 127.69, 127.60, 127.57, 127.52 (20C,
Ph), 95.45 (C-1), 81.49 (C-3), 79.77 (C-2), 78.20 (C-4), 75.76, 73.54, 73.13,
68.74 (4C, OCH2Ph) 60.21 (C-5); MS (CI): m/z 509 (M-1)þ, 419 (M-CH2Ph)þ,
403 (M-OCH2Ph)þ, 181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
HRMS: Theoretical molecular weight for C33H33O5 (M-1)þ 421.247639,
experimental molecular weight: 421.249118.
2,3,4-Tri-O-benzyl-a,b-L-arabinopyranose (3a)
A solution of 2a (1.68 g, 3.3 mmol) in a mixture of 4 M HCl-acetonitrile
16:10 (13 mL) was heated at 808C for 22 h. The mixture was concentrated to
dryness and extracted with CH2Cl2 (50 mL). The extracts were washed with
aq NaHCO3 satd solution (10 mL ꢀ 3), dried (anhydrous MgSO4), and concen-
trated to dryness. The residue was purified by column chromatography (1:1
tert-butylmethyl ether-hexane, Rf ¼ 0.14) to give the title compound as a
white solid (1.1 g, 80%); m.p. 84.1–84.88; [a]D þ 69 (c 0.99, dichloromethane);
1
IR (cm21): 3364 (OH), 3032 (Ph), 1098 (C-O-CH2Ph) 741, 697 (Ph); H NMR
(CDCl3, 500 MHz): d (ppm) a,b anomers in 43:56 ratio; 7.31 (m, 30H, 3 Ph, a
and b anomers), 5.17 (dd, 1H, H-1b, J1,2 ¼ 2.0 Hz, J1,OH ¼ 5.2 Hz,), 4.87 (dd,
1H, H-1a, J1,2 ¼ 10.0 Hz, J1,OH ¼ 2.1 Hz,), 4.80–4.52 (m, 12H, 3 CH2Ph,
a and b anomers), 4.04 (1H, dd, H-5Ab, J4,5A ¼ 8.7 Hz, J5A,5B ¼ 11.4 Hz),
3.92–3.76 (7H, m, H-2b/3a/3b/4a/4b/5Aa/5Ba), 3.67–3.63 (2H, m, H-5Bb/
2a), 3.06 (1H, d, OHb); 13C NMR (CDCl3, 125 MHz): d (ppm) 138.40, 138.21,
138.12, 137.88, 137.69, 137.45 (6C, Ph, a and b anomers), 128.52, 128.47,
128.45, 128.39, 128.06, 128.00, 127.96, 127.93, 127.82, 127.78, 127.69, 127.65
(30C, Ph a and b anomers), 93.46 (C-1a), 92.09 (C-1b), 76.76 (C-2b), 76.20
(C-2a), 76.09 (C-3a), 75.43 (C-3b), 73.81, 73.62 (2C, OCH2Ph, a and/or b
anomers), 73.01 (C-4a), 72.83, 72.70 (2C, OCH2Ph, a and/or b anomers),
72.09 (C-4b), 61.00 (C-5b), 58.24 (C-5a); MS (CI): m/z 403 (M-OH)þ, 329
(M-CH2Ph)þ, 253 (M-CH2Ph-Ph þ H)þ, 181 (PhCH2CHPh)þ, 107 (PhCH2O)þ,

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91 (PhCH2)þ. MS (CI): m/z 253 (M-CH2Ph-Ph þ H)þ, 181 (PhCH2CHPh)þ,
91 (PhCH2)þ.
Anal. Calcd for C26H28O5: C, 74.26; H, 6.71. Found: C, 74.06; H, 6.75.
2,3,4-Tri-O-benzyl-a,b-D-xylopyranose (3b)
This was obtained from 2b as a white solid (85% yield), following the pro-
cedure described above for 2a; m.p. 131.2–131.68C; [a]D þ 18.4 (c 0.38, dichloro-
methane); IR (cm21): 3409 (OH), 3088, 3064, 3030 (Ph), 1074 (C-O-CH2Ph) 735,
1
695 (Ph); H NMR (CDCl3, 500 MHz): d (ppm) a and b anomers in 77:23 ratio;
7.31 (m, 30H, 3 Ph a and b anomers), 5.12 (d, 1H, H-1a, J1, 2 ¼ 3.5 Hz), 4.90–
4.62 (m, 13H, H-1b, 3 CH2Ph from a and b anomers), 3.96 (1H, dd, H-5b,
J ¼ 4.5 Hz, J ¼ 11.5 Hz), 3.87 (1H, t, H-3a, J2,3 ¼ J3,4 ¼ 8.5 Hz), 3.81 (1H, t,
H-5Aa, J5A,5B ¼ J5A,4 ¼ 11 Hz), 3.67 (1H, dd, H-5Bb, J4,5B ¼ 5.0 Hz), 3.62 (1H,
m, H-3b), 3.59–3.53 (2H, m, H-4a/4 b), 3.49 (1H, dd, H-2a, J2,3 ¼ 3.5 Hz,
J3,4 ¼ 9 Hz), 3.31 (1H, m, H-2b); 13C NMR (CDCl3, 125 MHz): d (ppm) 138.64,
138.49, 138.33, 138.23, 138.08, 137.81 (6C, Ph, a and b anomers), 128.50,
128.43, 128.37, 128.07, 128.03, 127.98, 127.86, 127.79, 127.76, 127.65 (30C, Ph
a and b anomers), 97.74 (C-1b), 91.48 (C-1a), 83.17 (C-3b), 82.31 (C-2b), 80.46
(C-3a), 79.47 (C-2a), 77.54, 77.47 (C-4a/b), 75.47, 74.75, 73.44, 73.25, 73.19
(6C, OCH2Ph, a and b anomers), 63.73 (C-5b), 60.40 (C-5a); MS (CI): m/z 403
(M-OH)þ, 329 (M-CH2Ph)þ, 253 (M-CH2Ph-Ph þ H)þ, 181 (PhCH2CHPh)þ, 107
(PhCH2O)þ, 91 (PhCH2)þ.
HRMS: Theoretical molecular weight for C26H27O4 (M-OH)þ 403.190935,
experimental molecular weight: 403.189944.
2,3,4-Tri-O-benzyl-L-arabinitol (4a, ABnOH)
A solution of 3a (1.21 g, 2.86 mmol) in dry THF (5 mL) was cooled in an ice
bath for 15 min under argon atmosphere, and then a 1.0-M solution of LiAlH4
in THF (2.86 mL, 2.86 mmol) was added dropwise. The reaction proceeded in
inert atmosphere. The reaction mixture was stirred for 2 h at rt until the
reaction had finished. Aq Na2SO4 satd solution (0.86 mL) was added and the
mixture was stirred for 15 min and then diluted with CH2Cl2 (20 mL). The
aluminum salts were filtered off, and the solution was evaporated under
vacuum to dryness. The white solid was purified by column chromatography
(1:1 tert-butylmethyl ether-hexane, Rf ¼ 0.09) to give the title compound as a
white solid (1.17 g, 96%); m.p. 75.7–76.88; [a]D þ 7.48 (c 0.96, dichloro-
methane); IR (cm21): 3421 (OH), 3064, 3033 (Ph), 1064 (C-O-CH2Ph) 734,
1
697 (Ph); HNMR (CDCl3, 500 MHz): d (ppm) 7.38 (m, 15H, 3 Ph), 4.79 (1H,
d, CHAHB-O-Ph, JHA,HB ¼ 11.5 Hz), 4.72 (1H, d, CHAHB-O-Ph), 4.69 (1H, d,
CHCHD-O-Ph, JHC,HD ¼ 12.0 Hz), 4.64 (1H, d, CHEHF-O-Ph, JHE,HF
¼
11.5 Hz), 4.62 (1H, d, CHEHF-O-Ph), 4.56 (1H, d, CHCHD-O-Ph), 3.94–3.72

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
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(7H, m, H-1A, H-1B, H-2, H-3, H-4, H-5A, H-5B), 2.38 (1H, t, OH, J ¼ 6.4 Hz),
2.25 (1H, dd, OH, J ¼ 7.0; J ¼ 4.8 Hz); 13C NMR (CDCl3, 125 MHz): d (ppm)
138.11, 137.98, 137.92 (3C, Ph), 128.53, 128.51, 128.50, 128.29, 127.98,
127.97, 127.91, 127.89, 127.83 (15C, Ph), 79.44, 79.26, 79.02 (C-2, C-3, C-4),
74.27, 72.71, 72.07 (3C, OCH2Ph) 61.38, 60.79 (C-1, C-5); MS (CI): m/z 423
(M þ 1)þ, 331 (M-CH2Ph)þ, 271 (C17H19O3)þ 181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
Anal. Calcd for C26H30O5: C, 73.91; H, 7.16. Found: C, 73.67; H, 7.50.
2,3,4-Tri-O-benzylxylitol (4b, XBnOH)
This was obtained from 3b as an oil (92% yield), following the procedure
described above for 4a. IR (cm21): 3434 (OH), 3062, 3031 (Ph), 1063 (C-O-
CH2Ph) 737, 698 (Ph); 1H NMR (CDCl3, 500 MHz): d (ppm) 7.33 (m, 15H, 3 Ph),
4.72 (2H, s, CH2-O-Ph in C-3), 4.65 (2H, d, CHAHB-O-Ph, JHA,HB ¼ 11.5 Hz), 4.64
(2H, d, CHAHB-O-Ph), 3.81 (1H, t, H-3, J3,4 ¼ J2,3 ¼ 5.5 Hz), 3.80 (2H, dd, H-1A/
H-5A, J1A,2 ¼ J5A,4 ¼ 4.5 Hz), 3.74 (2H, dd, H-2/H-4, J1B,2 ¼ J5B,4 ¼ 9.8 Hz),
3.65 (2H, dd, H-1B/H-5B), 2.18 (2H, sa, OH-1/OH-2); 13C NMR (CDCl3,
125 MHz): d (ppm) 137.95, 137.89 (3C, Ph), 128.51, 128.46, 128.36, 128.03,
127.93 (15C, Ph), 79.39 (C-3), 79.04 (C-2, C-4), 74.57 (1C, OCH2Ph in C-3), 72.80
(2C, OCH2Ph in C-2/C-4) 61.56 (C-1, C-5); MS (CI): m/z 423 (M þ 1)þ, 331
(M-CH2Ph)þ, 271 (C17H19O3)þ 181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
HRMS: Theoretical molecular weight for C26H31O5 (M þ 1)þ 423.217149,
experimental molecular weight: 423.215830.
1,5-Diazido-1,5-dideoxy-2,3,4-tri-O-benzyl-L-arabinitol (5a)
To a solution of triphenylphosphine (3.05 g, 11.64 mmol, 2.2 equiv) in dry
THF (13 mL) at 08C, a commercial 40% solution of diethylazodicarboxylate
(DEAD) in toluene (5.3 mL, 11.6 mmol, 2.2 equiv) was added dropwise, and
the mixture was stirred for 5 min prior to the sequential dropwise addition of
diphenylphosphoryl azide (DPPA) (2.4 mL, 11.1 mmol, 2.1 equiv) and a
solution of 1.12 g of 4a (2.64 mmol) in THF (13 mL). The reaction solution
was stirred for 3 h and then concentrated to dryness. The residue was
purified by column chromatography (1:3 dichloromethane-hexane, Rf ¼ 0.13)
to give the title compound as a colorless oil (1.19 g, 96%); [a]D þ 48 (c 0.61,
dichloromethane); IR (cm21): 3062, 3031 (Ph), 2100 (N3), 1073 (C-O-CH2Ph)
1
737, 697 (Ph); H NMR (CDCl3, 500 MHz): d (ppm) 7.35 (m, 15H, 3 Ph), 4.74
(1H, d, CHAHB-O-Ph, JHA,HB ¼ 11.6 Hz), 4.69 (1H, d, CHCHD-O-Ph,
JHC,HD ¼ 11.6 Hz), 4.66 (1H, d, CHEHF-O-Ph, JHE,HF ¼ 11.5 Hz,), 4.66 (1H, d,
CHAHB-O-Ph), 4.57 (1H, d, CHEHF-O-Ph,) 4.49 (1H, d, CHCHD-O-Ph), 3.79
(3H, m, H-2/H-3/H-4), 3.63 (1H, dd, H1A, J1A,IB ¼ 13.3 Hz, J1A,2 ¼ 2.8 Hz),
3.51 (1H, dd, H1B, J1B,2 ¼ 5.0 Hz), 3.47 (1H, dd, H5A, J5A,5B ¼ 12.6 Hz,
J5A,4 ¼ 6.1 Hz), 3.42 (1H, dd, H5B, J5B,4 ¼ 5.1 Hz); 13C NMR (CDCl3,

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M. V. de P. Ban˜ez et al.
134
125 MHz): d (ppm) 137.76, 137.53 (3C, Ph), 128.52, 128.50, 128.46, 128.15,
128.04, 127.99 (15C, Ph), 78.77, 78.19, 78.16 (C-2/C-3/C-4), 74.57, 73.35,
72.41 (3C, OCH2Ph), 51.68, 50.92 (C-1, C-5); MS (CI): m/z 445 (M 2 N2 þ 1)þ,
417 (M 2 2N2 þ 1)þ, 181 (PhCH2CHPh), 91 (PhCH2)þ.
Anal. Calcd for C26H28N6O3: C, 66.09; H, 5.97; N, 17.78. Found: C, 65.97; H,
5.70; N, 17.43.
1,5-Diazido-1,5-dideoxy-2,3,4-tri-O-benzylxylitol (5b)
This was obtained from 4b as an oil (89% yield), following the procedure
described above for 5a. IR (cm21): 3077, 3031 (Ph), 2099 (N3), 1076 (C-O-
1
CH2Ph) 736, 698 (Ph); H NMR (CDCl3, 500 MHz): d (ppm) 7.34 (m, 15H, 3
Ph), 4.70 (2H, d, CHAHB-O-Ph, CHCHD-O-Ph, JHA,HB ¼ JHC,HD ¼ 11.50 Hz),
4.67 (2H, s, CHEHF-O-Ph), 4.62 (2H, d, CHAHB-O-Ph, CHCHD-O-Ph), 3.74
(2H, m, H2/H4), 3.69 (1H, t, H3, J2,3 ¼ J3,4 ¼ 5.0 Hz), 3.44 (2H, dd, H1A/5A,
J1A,IB ¼ J5A,5B ¼ 12.5 Hz, J1A,2 ¼ J5A,4 ¼ 4.5 Hz) 3.34 (2H, dd, H1B/5B,
J1B,2 ¼ J5B,4 ¼ 6.5 Hz); 13C NMR (CDCl3, 125 MHz): d (ppm) 137.73, 137.62
(3C, Ph), 128.53, 128.50, 128.40, 128.20, 128.08, 128.03 (15C, Ph), 77.74 (C-
2/C-4), 77.63 (C-3), 74.63, 73.21 (3C, OCH2Ph) 51.33 (C-1, C-5); MS (CI): m/z
445 (M 2 N2 þ 1)þ, 417 (M 2 2N2 þ 1)þ, 181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
Anal. Calcd for C26H28N6O3: C, 66.09; H, 5.97; N, 17.78. Found: C, 65.94; H,
5.61; N, 17.78.
1,5-Diamino-1,5-dideoxy-2,3,4-tri-O-benzyl-L-arabinitol
(6a, ABnNH2)
A solution of 5b (0.80 g, 1.693 mmol) in methanol (9 mL) was stirred with
10% Pd/C (80 mg) for 2 h at rt under hydrogen atmosphere at 0.5 bar
pressure. The mixture was then diluted with methanol, and the catalyst was
filtered off through diatomaceous earth and concentrated, giving the title
product as a pure oil (0.66 g, 92% yield). IR (cm21): 3373, 3278 (NH2), 3030
1
(Ph), 1071 (C-O-CH2Ph) 743, 698 (Ph); H NMR (CDCl3, 500 MHz): d (ppm)
7.28 (m, 15H, 3 Ph), 4.72 (1H, d, CHAHB-O-Ph, JHA,HB ¼ 11.5 Hz), 4.67 (1H,
d, CHAHB-O-Ph), 4.64 (1H, d, CHCHD-O-Ph, JHC,HD ¼ 11.5 Hz), 4.59 (1H, d,
CHCHD-O-Ph), 4.53 (1H, d, CHEHF-O-Ph, JHE,HF ¼ 15.5 Hz), 4.51 (1H, d,
CHEHF-O-Ph), 3.84 (1H, dd, H-3, J ¼ 4.1 Hz, J ¼ 5.2 Hz), 3.64 (1H, m, H-2),
3.59 (1H, m, H-4), 3.03 (1H, dd, H-1A, J1A,2 ¼ 6.0 Hz, J1A,1B ¼ 13.8 Hz), 2.99
(1H, dd, H-1B, J1B,2 ¼ 4.2 Hz), 2.93 (1H, dd, H-5A, J5A,4 ¼ 4.6 Hz, J5A,5B
¼
13.2 Hz), 2.82 (1H, dd, H-5B, J5B,2 ¼ 6.4 Hz), 1.95 (4H, s, NH2); 13C NMR
(CDCl3, 125 MHz): d (ppm) 138.14, 138.08, 137.87, (3C, Ph), 129.33, 128.47,
128.44, 128.40, 128.02, 127.96, 127.90, 127.84, 127.80 (15C, Ph), 79.69 (C-4),
79.26 (C-2), 78.87 (C-3), 74.15, 73.42, 71.92 (3C, OCH2Ph) 41.51 (C-1), 40.72
(C-2); MS (CI): m/z 421 (M þ 1)þ, 91 (PhCH2)þ.

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
135
HRMS: Theoretical molecular weight for C26H33N2O3 (M þ 1)þ 421.249118,
experimental molecular weight: 421.248401.
1,5-Diamino-1,5-dideoxy-2,3,4-tri-O-benzylxylitol
(6b, XBnNH2)
This was obtained from 5b as an oil (97% yield), following the procedure
described above for 6a. IR (cm21): 3331 (NH2), 3030 (Ph), 1068 (C-O-CH2Ph)
1
735, 697 (Ph); H NMR (CDCl3, 500 MHz): d (ppm) 7.34 (m, 15H, 3 Ph), 4.76
(2H, s, CH2-O-Ph), 4.68 (2H, d, CHAHB-O-Ph/CHCHD-O-Ph, JHA,HB
¼
JHC,HD ¼ 11.5 Hz), 4.63 (2H, d, CHAHB-O-Ph, CHCHD-O-Ph), 3.73 (1H, t,
H-3, J2,3 ¼ J3,4 ¼ 5.5 Hz), 3.60 (2H, m, H2/4), 2.92 (2H, dd, H-1A/5A,
J1A,2 ¼ J5A,4 ¼ 4.5 Hz, J1A,1B ¼ J5A,5B ¼ 13.3 Hz,), 2.78 (2H, dd, H-1B/5B,
J1B,2 ¼ J5B,4 ¼ 6.1 Hz,), 1.73 (4H, s, NH2); 13C NMR (CDCl3, 125 MHz): d
(ppm) 138.44, 138.37, (3C, Ph), 128.46, 128.04, 127.86, 127.79, (15C, Ph),
80.91 (C-2, C-4), 78.77 (C-3), 74.37, 73.03 (3C, OCH2Ph) 41.88 (C-1,C-5).
HRMS: Theoretical molecular weight for C26H33N2O3 (M þ 1)þ 421.249118,
experimental molecular weight: 421.247639.
1,5-Dideoxy-1,5-dimesyl-2,3,4-tri-O-benzyl-L-arabinitol (7)
A solution of mesyl chloride (0.39 mL, 5 mmol, 1.25 equiv) in dry dichloro-
methane (1.5 mL) was added dropwise to a cold solution (08C) of 0.85 g of 2,3,4-
tri-O-benzyl-L-arabinitol (4a, ABnOH, 2 mmol) and triethylamine (0.7 mL,
5 mmol, 1.25 equiv) in dry dichloromethane (5 mL), under argon atmosphere.
The reaction was allowed to warm up to rt and was monitored by thin layer
chromatography (TLC, tert-butylmethyl ether). The starting material was
consumed in 90 min. The reaction mixture was diluted with water (5 mL),
and the aqueous phase was extracted with CH2Cl2 (3 ꢀ 10 mL). The
combined organic layers were washed first with aq 4 M HCl solution (10 mL)
and then with aq NaHCO3 sat solution (10 mL), dried (anhydrous MgSO4),
and concentrated under vacuum. The residue was purified by column chrom-
atography (1:1 tert-butylmethyl ether-hexane, Rf ¼ 0.08) to give the title
compound as a colorless oil (0.90 g, 78%). [a]D þ 1.78 (c 1.85, dichloromethane);
IR (cm21): 3065, 3036 (Ph), 1356, 1175 (OSO2CH3), 1085 (C-O-CH2Ph) 736,
1
701 (Ph); H NMR (CDCl3, 500 MHz): d (ppm) 7.34 (15H, m, 3 Ph), 4.73 (1H,
d, CHAHB-O-Ph, JHA,HB ¼ 11.4 Hz), 4.65 (1H, d, CHAHB-O-Ph), 4.70 (1H, d,
CHCHD-O-Ph, JHC,HD ¼ 11.7 Hz), 4.57 (1H, d, CHCHD-O-Ph), 4.68 (1H, d,
CHEHF-O-Ph, JHE,HF ¼ 15.3 Hz), 4.49 (1H, d, CHEHF-O-Ph), 4.37 (1H, d,
H1 A, J1A,2 ¼ 1.0 Hz), 4.36 (1H, d, H1B, J1B,2 ¼ 1.8 Hz), 4.02–3.92 (2H, m,
H-2/H-4), 3.80 (1H, dd, H-3, J2,3 ¼ 4.1 Hz, J3,4 ¼ 5.5 Hz), 4.62 (1H, dd, H-5A,
J5A,5B ¼ 11.4 Hz, J5A,4 ¼ 2.9 Hz), 4.41 (1H, dd, J5B,4 ¼ 5.3 Hz), 2.93 (3H, s,
CH3SO32), 2.91 (3H, s, CH3SO3-); 13C NMR (CDCl3, 125 MHz): d (ppm)

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137.43, 137.35, 137.32 (3C, Ph), 128.93, 128.58, 128.55, 128.24, 128.14, 128.07,
128.04, 127.83 (15C, Ph), 77.48, 77.36, 77.03 (C-2/C-3/C-4), 74.35, 73.65, 72.85
(3C, OCH2Ph), 69.01, 68.76 (C-1/C-5), 37.47, 37.30 (2CH3SO32). MS (CI): m/z
181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
Anal. Calcd for C28H34O9S2: C, 58.11; H, 5.92; S, 11.08. Found: C, 58.51; H,
6.04; S, 10.95.
[(2S,3S,4S )-3,4-bis(benzyloxy)-tetrahydrofuran-2-yl]methyl
methanesulfonate (8)
To a solution of the dimesyl arabinitol derivative 7 (0.70 g, 1.21 mmol) in a
mixture of acetonitrile-water 10:1 (11 mL) was added sodium azide (0.20 g,
3.02 mmol), and the solution was heated at 808C for 18 h. The reaction was
followed by TLC, and a main product was detected (Rf ¼ 0.33 in tert-butyl-
methyl ether-hexane 2:1). The mixture was evaporated and then dissolved in
a mixture of dichloromethane-water 2:1 (60 mL). The organic layer was dried
(anhydrous Na2SO4) and the solvents were evaporated. The residue was
purified by column chromatography (1:1 tert-butylmethyl ether-hexane,
Rf ¼ 0.1) to give the title compound as a white solid (0.21 g, 44%), m.p. 79.9–
80.48C. [a]D 2338 (c 1.28, dichloromethane); IR (cm21): 3031 (Ph), 1356, 1175
1
(OSO2CH3), 1097 (C-O-CH2Ph) 742, 699 (Ph); H NMR (CDCl3, 500 MHz): d
(ppm) 7.34 (10H, m, 2 Ph), 4.60 (2H, s, CH2-O-Ph), 4.54 (2H, d, CH2-O-Ph,
J ¼ 1.8 Hz), 4.36 (1H, dd, H-10A, J1 A,1 B ¼ 11.0 Hz; J1 A,2 ¼ 5.1 Hz), 4.33 (1H,
0
0
0
dd, H-10B, J1 B,2 ¼ 5.9 Hz), 4.16 (1H, ddd, H-2, J2,3 ¼ 3.3 Hz), 4.12 (1H, dt,
0
H-4, J4,5A ¼ 1.3 Hz, J3,4 ¼ J4,5B ¼ 4.5 Hz), 4.08 (1H, bd, H-5A, J5A,5B
¼
10.1 Hz), 4.03–3.90 (2H, m, H-3/5B), 3.02 (3H, s, CH3SO32); 13C NMR
(CDCl3, 125 MHz): d (ppm) 137.44, 137.29 (2C, Ph), 128.61, 128.59, 128.11,
128.03, 127.84, 127.82 (10C, Ph), 83.59 (C-2), 82.60 (C-4), 81.40 (C-3), 72.06,
72.00, 71.48 (C-5, 2 OCH2Ph), 69.04 (C-1), 37.67 (CH3SO32). MS (CI): m/z
391 (M-1)þ, 301 (M-PhCH2)þ, 285 (M-PhCH2O)þ, 271 (M-PhCH2O-CH3)þ,
181 (PhCH2CHPh)þ, 91 (PhCH2)þ.
HRMS: Theoretical molecular weight for C20H25O6S (M-1)þ 391.121536,
experimental molecular weight: 391.122398.
Polyurethane PU-(ABnOH-HMDI)
In a typical procedure, the carbohydrate-based diol 2,3,4-tri-O-benzyl-L-ara-
binitol (4a, ABnOH) (0.21 g, 0.5 mmol) was charged in a round-bottom flask with
aninlet ofAr/vacuum. The system was treated withthree cyclesof vacuum-argon
before the addition, via cannula, of dried THF (2 mL). The mixture was stirred to
homogenization, and the diisocyanate (HMDI, 82 mL, 0.5 mmol) was added under
argon atmosphere, followed by the catalyst (dibutyltin dilaurate, one drop). The
polymerization solution was stirred for 3 h under argon atmosphere, at rt. Tert-

Potential Degradable Hydrophilic-Hydrophobic Polyurethanes and Polyureas
137
butanol (1 mL) was added, the mixture was stirred for 30 min, and the solution
was added dropwise into cold diethyl ether (150 mL), where the polymer PU-
(ABnOH-HMDI) precipitated. The polyurethane was purified by redissolution
in a small volume of chloroform (2 mL), and reprecipitation into diethyl ether.
The pure polymer (white solid) was dried under vacuum for 2 d and stored in a
desiccator (0.28 g, 95% yield). [a]D 20.038 (c 1.0, dichloromethane); Mw 52100;
Mn 29200; Mw/Mn 1.8; DP 49. IR: n (cm21) 3334 (N-H), 3056, 3031 (C-H ar),
1703 (C55O urethane), 1536 (N-H urethane), 1097 (C-O-CH2Ph), 739, 699 (ar).
1H NMR (CDCl3, 500 MHz): d (ppm) 7.31 (m, 15H, 3 Ph), 4.86 (bs, 2H, N-H),
4.79–4.17 (m, 10H, H-1/H5/3CH2Ph), 3.88 (bs, 2H, H-2/H4), 3.79 (m, 1H,
H-3), 3.13 (bs, 4H, CH2-a), 1.47 (bs, 4H, CH2-b), 1.31 (bs, 4H, CH2-c); 13C NMR
(CDCl3, 125 MHz): d (ppm) 156.37, 156.20 (C55O), 138.38, 138.14, 138.07 (3C,
Ph), 128.34, 128.17, 127.96, 127.89, 127.74, 127.66 (15C, Ph), 79.06 (C-3), 77.28,
77.03 (C-2/C4), 74.65, 73.13, 72.06 (3OCH2Ph), 63.52, 62.98 (C-1/C5), 40.91
(CH2-a), 29.85 (CH2-b), and 26.34 (CH2-c).
.
Anal. Calcd. for (C34H42N2O7) (H2O)0.5: C, 68.09; H, 7.23; N, 4.67. Found:
C, 68.05; H, 7.34; N, 4.95.
Polyurea PUR-(ABnNH2-HMDI)
In a typical procedure, the carbohydrate-based diamine 1,6-diamino-1,6-
dideoxy-2,3,4-tri-O-benzyl-L-arabinitol (6a, ABnNH2) (145 mg, 0.345 mmol)
was charged in a round-bottom flask with an inlet of Ar/vacuum. The system
was treated with three cycles of vacuum-argon before the addition, via
cannula, of dried N,N-dimethylacetamide (DMA) (2 mL). The mixture was
stirred to homogenization, the di-isocyanate (HMDI, 82 mL, 0.5 mmol) was
added under argon atmosphere, and the mixture was stirred at rt for 30 min.
The catalyst was then added (dibutyltin dilaurate, one drop), and stirring
was continued for a further 30 min under argon atmosphere, at rt. 1-Decanea-
mine (0.5 mL) was added, the mixture was stirred for 30 min, and the reaction
mixture was dropped into cold tert-butylmethyl ether (tBME) (200 mL), where
the polymer PUR-(XBnNH2-HMDI) precipitated. The polyurea was purified by
t
several washes with BME. The pure polymer (pale yellow solid) was dried
under vacuum for 2 d and stored in a desiccator (0.2 g, 98% yield).
[a]D þ 0.018 (c 1.0, sulfuric acid). Mw 4100; Mn 3800; Mw/Mn 1.1. IR: n (cm21
)
3333 (N-H), 3054, 3029 (C-H ar), 1619 (C55O urea), 1077 (C-O-CH2Ph), 735,
1
697 (ar). H NMR (DMSO-d6 500 MHz): d (ppm) 7.32 (sa, 15H, 3 Ph), 5.86
(sa, 4H, N-H), 4.60 (sa, 6H, 3CH2Ph), 3.72 (sa, 2H, H-2/H-4) 3.59 (sa, 1H,
H-3), 3.41 (sa, 2H, H-1A/H-5A), 3.20 (sa, 2H, H-1B/H-5B), 2.96 (sa, 4H, CH2-
a), 1.34 (sa, 4H, CH2-b), 1.25 (sa, 4H, CH2-c); 13C NMR (DMSO-d6, 125 MHz):
d (ppm) 158.62 (C55O), 139.16 (3C, Ph), 128.58, 128.36, 128.12, 127.79 (15C,
Ph), 79.64 (C-2/C4), 78.89 (C-3), 74.06, 72.40 (3OCH2Ph), 39.87 (CH2-a),
39.66 (C-1/C5), 30.53 (CH2-b), and 22.56 (CH2-c).

´
M. V. de P. Ban˜ez et al.
138
Anal. Calcd. for (C34H42N2O7): C, 69.36; H, 7.53; N, 9.52. Found: C, 69.72;
H, 8.05; N, 10.12.
ACKNOWLEDGMENT
´
´
We thank the CICYT (Comision Interministerial de Ciencia y Tecnologıa) of
Spain for financial support (Grant MAT2006-13209-C02-01).
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