Microwave-assisted efficient preparation of novel carbohydrate tetrazole derivatives

Article abstract of DOI:10.1016/j.carres.2007.02.007

A series of novel N-1, N-2 and S-5 saccharide substituted tetrazole derivatives linked at anomeric and nonanomeric positions were obtained from commercial tetrazoles under microwave irradiation. Yields are compared with conventional methodologies.

Full text of DOI:10.1016/j.carres.2007.02.007

Carbohydrate Research 342 (2007) 1096–1100
Note
Microwave-assisted efficient preparation of novel
carbohydrate tetrazole derivatives
a
a
a
a,
*
Mara Rubia Couri, In a´ cio Luduvico, Leandro Santos, Rosemeire Alves,
b
a
Maria Auxiliadora Prado and Rossimiriam Freitas Gil
a
Departamento de Qu ı´ mica-ICEx, Universidade Federal de Minas Gerais, CEP: 31270-901 Belo Horizonte, MG, Brazil
b
Departamento de Produtos Farmac eˆ uticos-Faculdade de Farm a´ cia, Universidade Federal de Minas Gerais,
CEP: 31270-901 Belo Horizonte, MG, Brazil
Received 6 November 2006; received in revised form 8 February 2007; accepted 9 February 2007
Available online 16 February 2007
Abstract—A series of novel N-1, N-2 and S-5 saccharide substituted tetrazole derivatives linked at anomeric and nonanomeric
positions were obtained from commercial tetrazoles under microwave irradiation. Yields are compared with conventional
methodologies.
ꢀ
2007 Elsevier Ltd. All rights reserved.
Keywords: Tetrazoles; Glycosyl tetrazoles; Microwave irradiation
A number of tetrazole derivatives exhibit biological
activities and have found applications as carboxylic
surrogates. The development of tetrazole chemistry
with various frameworks. It has been postulated that
regardless of the nature of the alkylating agent and the
properties of the reaction medium, the alkylation of
tetrazole and 5-substituted tetrazoles results in the
formation of the corresponding 1- and 2-substituted
tetrazoles. This reaction has great theoretical interest,
since it may serve as a convenient model for the study
of heterocyclic substrates with dual reactivity. Various
groups can be used as alkylating agents, including sulfu-
ric and aromatic sulfonic acid esters, in addition to sim-
1
during the past 20 years can be ascribed to their diverse
applications in medicine, biochemistry, agriculture, photo-
graphy, information recording systems, explosives and
2
,3
others. The ability of tetrazole compounds to mimic
the carboxylic functionality has motivated the incorpo-
ration of tetrazole derivatives into biologically active
molecules. This has led to applications in therapy result-
ing in compounds with anti-hypertensive, anti-allergic
3
ple alkyl halides. Little attention, however, has been
paid to carbohydrate analogues.
4
and antibiotic activities.
Various modifications of the structure of tetrazoles
have been carried out in order to obtain compounds
with different physicochemical properties and subse-
quently with different pharmacodynamic and pharmaco-
The application of microwave irradiation to organic
synthesis for conducting reactions at accelerated rates
is an emerging technique. In fact, in recent years, the
use of microwaves has become popular among chemists
both as a means to improve classical organic reactions
(shortening reaction times and/or improving yields)
5
kinetic properties. Novel methods of synthesis of
substituted tetrazoles have been developed in recent
years, including a simple and effective alkylation method
for the synthesis of mono- and di-substituted tetrazoles
6
and promote new reactions. Availability of suitable
commercial microwave equipments, domestic ovens
and monomode reactors has also contributed to the
7
development of this technique significantly.
*
Corresponding author. Tel.: +55 3134995721; fax: +55
134995700; e-mail: rbrondi@terra.com.br
Knowing the broad spectrum of biological activities
and the significant applications of the tetrazole ring
3
0
008-6215/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2007.02.007

M. R. Couri et al. / Carbohydrate Research 342 (2007) 1096–1100
1097
systems, we have focussed our interest on improving the
synthesis of saccharide tetrazole derivatives. The pur-
pose of our research was an attempt to simplify tetrazole
substitution by considering different heating modes
Table 1. Comparative glycosylation of tetrazoles under microwave
irradiation and under classical conditions
Tetrazole Product
Microwave
irradiation
Classical reactions
(
microwave irradiation and oil bath) and to prepare a
Time (h) Yield (%) Time (h) Yield (%)
number of carbohydrate heterocyclic derivatives of
potential synthetic and pharmacological interest. To date,
we are not aware of any report concerning the prepara-
tion of 1- and 2-substituted carbohydrate tetrazole
derivatives involving the use of microwaves as the heat-
ing source. In the method reported therein, saccharide
substitution of tetrazoles was accomplished using a
domestic microwave oven specially modified for organic
synthesis and an open vessel.
3
3
4
4
5
3
4
4
5
6a
6b
6c
6d
6e
7a
7b
7c
7d
2.75
2.75
2.0
2.0
0.5
1.30
1.25
1.25
0.66
10
64
37
41
90
84
42
30
91
18.0
18.0
8.0
8.0
2.5
48.0
8.0
8.0
8
56
27
27
81
84
41
25
90
6.0
1
3
sponding tetrazoles. C NMR spectroscopy is particu-
larly useful in this respect. The literature shows that
the C NMR shifts for C-5 (C-tetrazolic) for the 2-
substituted isomer is consistently 10 ppm at higher field
as compared to that for the corresponding 1-substituted
isomer.
characterization of the isomeric tetrazoles 6a and 6b,
c and 6d, 7b and 7c. HMBC experiments were carried
out for structure confirmation and revealed that the
Thus, in the present study, novel saccharide substi-
tuted tetrazoles were synthesized starting from 2,3,4,6-
tetra-O-acetyl-a-D-glucopyranosyl bromide (1) or
1
3
methyl
oside (2) in reaction with commercial tetrazoles (Scheme
) under microwave irradiation. The reactions were car-
2,3,6-tri-O-benzyl-4-O-triflyl-a-D-glucopyran-
9
,10
It is interesting to point the unequivocal
1
ried out by mixing the electrophilic agent 1 or 2, potas-
sium carbonate, and the respective commercial tetrazole
compound in acetone (Scheme 1). After the appropriate
time (Table 1), complete conversion to the correspond-
ing product was monitored by TLC. To check the pos-
sible specific effect of microwaves, results obtained in a
microwave oven were compared with conventional heat-
ing (D) in the same conditions.
6
0
0
cross correlation of H-1 and H-4 with the tetrazolic
carbon atoms occurs solely in derivatives 6a, 6c and
b, respectively, due to the J coupling.
3
7
Although conversions were obtained through both
conditions, the isolated yields were improved and the
reaction time was shortened in the case of the micro-
wave reaction conditions. The compounds obtained in
1. Experimental
1.1. General methods
8
this work are novel, with the exception of 6e.
Commercial reagents were used as received. Tetrazole
derivatives 3–5 were obtained from Sigma–Aldrich.
Dry acetone was prepared after agitation with potas-
1
13
H and C NMR analysis of the respective products
clearly confirmed the site of substitution of the corre-
OAc
O
N
N
AcO
AcO
N
N
N
N
5
'
OAc
6
a R =
6b R =
1
'
N
N
3
'
OAc
Br
O
Ph
Ph
1
AcO
AcO
R
N
N
N
K2CO3, acetone, MW or
3
N
OAc
N
H
N
N
H
N
N
S
N
6c
R =
6d R =
6e R =
N
N
N
N
N
Ph
5
N
1
X
Y
OBn
3
4
5
X = Ph, Y = H
X = H, Y = H
X = SH, Y = Ph
N
N
N
N
N
O
N
7b R =
TfO
BnO
5
'
OBn
7a R =
N
R
N
1
'
H
3'
OBn
Ph
O
OCH3
2
N
N
N
N
K2CO3, acetone, MW or
BnO
N
N
OBn
OCH3
7c
R =
7d R =
N
N
H
S
Ph
Scheme 1.

1098
M. R. Couri et al. / Carbohydrate Research 342 (2007) 1096–1100
0
sium carbonate for 24 h at room temperature, and then
distilled. H and C NMR spectra were recorded using
a BRUKER AVANCE DRX/ 200 or 400 apparatus in
2H, J6
0
0
12.5, J
0
0
6 a;5
5.4 Hz, H-6 a), 4.24–4.21 (m,
a;6 b
0
1
13
0
1H, H-6 b), 4.01–3.98 (m, 1H, H-5 ), 2.13, 2.06, 2.02,
1.83 (4s, 12H, CH3); C NMR (50 MHz, CDCl ): d
1
3
3
CDCl with TMS as an internal standard. IR spectra
170.50, 170.35, 169.32, 168.33 (C@O), 155.99 (C-5),
3
were recorded on a Mattson Instruments Galaxy 3000.
Melting points were determined on a Mettler FP80HT
apparatus and are uncorrected. Elemental analyses were
carried out using a Fisons EA1108 CHNS-O apparatus.
The experiments were performed using a commercial
microwave oven (Panasonic Junior Smart NNS53BH)
specially modified for organic synthesis. The oven top
was cut to accommodate a reflux condenser and a steel
ring was used to avoid microwave leakage. The turnable
dish was turned off.
123.33 (C ), 132.26, 129.58, 129.38 (C
), 83.23
ipso
arom.
0
0
0
0
(C-1 ), 75.23 (C-5 ), 73.21 (C-3 ), 69.60 (C-2 ), 67.67
0
0
(C-4 ), 61.98 (C-6 ), 20.57, 20.39, 20.08 (CH CO). Anal.
3
Calcd for C H N O : C, 52.94; H, 5.04; N, 11.76.
2
1
24
4
9
Found: C, 52.94; H, 5.01; N, 10.83.
0
0
0
0
1.5. 2-(2 ,3 ,4 ,6 -Tetra-O-acetyl-b-D-glucopyranosyl)-5-
phenyltetrazole (6b)
2
0
White solid, mp 160–162 ꢁC; ½aꢀ ꢁ3.6 (c 1.0, CHCl ); IR
D
3
(
compression cell) m 2924, 1749, 1370, 1212, 1035, 933,
ꢁ
1
1
1
.2. Tetrazoles substitution by microwave irradiation
733 cm ; H NMR (400 MHz, CDCl ): d 8.18–8.15
3
(
J1
m, 2H, PhH), 7.51–7.48 (m, 3H, PhH), 6.14 (d, 1H,
0
0
0
9.4 Hz, H-2 ), 5.44
2 ;3
A mixture of 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl
0
0
9.4 Hz, H-1 ), 5.97 (t, 1H, J
0
;2
1
1
0
bromide (1) or methyl 2,3,6-tri-O-benzyl-4-O-triflyl-
(t, 1H, J
4 ), 4.31 (dd, 1H, J
(dd, 1H, J
0
0
9.4 Hz, H-3 ), 5.34 (t, 1H, J
0
0
9.4 Hz, H-
3
;4
4 ;5
1
2
0
0
a-D-glucopyranoside (2) (1.0 mmol), tetrazole deriva-
tives 3, 4 or 5 (1.5 mmol), K CO (15.0 mmol) and dried
0
0
12.6, J
0
0
5.0 Hz, H-6 a), 4.19
2.2 Hz, H-6 b), 4.06 (ddd, 1H, H-5 ),
6
a;6 b
6 a;5
0
0
0
0
2
3
6 a;5
1
3
acetone (5 mL), was irradiated with microwaves for an
appropriate length of time (Table 1). After complete
conversion to the corresponding product as indicated
by TLC, the solvent was removed under diminished
pressure. The residue was diluted with CH Cl and
2.08, 2.05, 1.84 (3s, 12H, CH CO); C NMR (50 MHz,
3
CDCl ): d 170.58, 170.18, 169.39, 168.23 (C@O), 165.78
3
(C-5), 130.86, 128.97, 127.18 (C
), 126.66 (C ),
arom.
ipso
0
0
0
0
86.76 (C-1 ), 75.17 (C-5 ), 73.14 (C-3 ), 69.85 (C-2 ),
0
0
67.51 (C-4 ), 61.52 (C-6 ), 20.68, 20.55, 20.20 (CH CO).
2
2
3
washed with water. The organic phase was dried over
anhyd Na SO , filtered and the product was purified
Anal. Calcd for C H N O : C, 52.94; H, 5.04; N,
11.76. Found: C, 53.49; H, 4.98; N, 11.95.
2
1
24
4
9
2
4
by silica gel chromatography (9.9:0.1–8.5:1.5 hexane–
EtOAc) to afford the respective substituted tetrazoles.
0
0
0
0
1.6. 1-(2 ,3 ,4 ,6 -Tetra-O-acetyl-b-D-glucopyranosyl)-
tetrazole (6c)
1
.3. Tetrazoles substitution by the conventional procedure
2
D
0
White solid, mp 165–167 ꢁC; ½aꢀ ꢁ12.5 (c 1.0, CHCl );
3
To a stirred soln of tetrazole 3, 4 or 5 (1.5 mmol) and
anhyd K CO (15.0 mmol) in dry acetone (5 mL), 1, or
2
IR (compression cell) m 2951, 1746, 1370, 1206, 1034,
922 cm ; H NMR (200 MHz, CDCl ): d 8.90 (s, 1H,
ꢁ
1 1
2
3
3
0
(1.0 mmol) was added. The soln was stirred under
H-5), 7.62 (d, 1H, J
0
0
9.3 Hz, H-1 ), 5.98 (t, 1H, J
0
0
1
;2
2 ;3
0
0
reflux for an appropriate length of time (Table 1). After
complete conversion to the corresponding product as
indicated by TLC, the solvent was evaporated under
diminished pressure. The residue was diluted with
CH Cl and washed with water (3 · 20 mL). The organic
9.3 Hz, H-2 ), 5.46 (t, 1H, J
0
0
9.3 Hz, H-3 ), 5.34 (t,
3
;4
0
0
1H, J4
0
0
9.3 Hz, H-4 ), 4.15–4.07 (m, 1H, H-5 ), 4.33
4.85 Hz, H-6 a), 4.26–4.22
(m, 1H, H-6 b), 2.18, 2.08 (2s, 12H, CH CO);
NMR (50 MHz, CDCl ): d 170.61, 170.04, 169.45,
169.12 (C@O), 141.68 (C-5), 84.47 (C-1 ), 75.62 (C-5 ),
72.41 (C-3 ), 70.42 (C-2 ), 67.61 (C-4 ), 61.49 (C-6 ),
;5
0
(dd, 1H, J6
0
0
12.6, J
0
0
a;6 b
0
6 a;5
13
C
3
2
2
3
0
0
phase was dried over anhyd Na SO , filtered and the
2
4
0
0
0
0
product was purified by silica gel chromatography
9.9:0.1–8.5:1.5 hexane–EtOAc) to give the respective
substituted tetrazole.
(
20.78, 20.64, 20.24, 19.29 (CH CO). Anal. Calcd for
3
C H N O : C, 45.00; H, 5.00; N, 14.00. Found: C,
1
5
20
4
9
4
5.58; H, 4.99; N, 13.69.
0
0
0
0
1
phenyltetrazole (6a)
.4. 1-(2 ,3 ,4 ,6 -Tetra-O-acetyl-b-D-glucopyranosyl)-5-
0
0
0
0
1.7. 2-(2 ,3 ,4 ,6 -Tetra-O-acetyl-b-D-glucopyranosyl)-
tetrazole (6d)
20
Colourless oil; ½aꢀ ꢁ43.8 (c 1.15, CHCl ); IR (compres-
D
3
2
D
0
sion cell) m 2924, 2852, 1744, 1366, 1206, 1033, 911,
White solid, mp 162–163 ꢁC; ½aꢀ ꢁ5.4 (c 1.15, CHCl );
3
ꢁ
1 1
7
31 cm ; H NMR (400 MHz, CDCl ): d 7.80 (d, 2H,
IR (compression cell) m 2951, 2924, 1744, 1369, 1208,
3
ꢁ
1 1
Jo,m 7.4 Hz, PhHortho), 7.67 (t, 1H, Jm,p 7.4 Hz, PhH ),
.60 (t, 2H, PhHmeta), 5.92 (t, 1H, J
.69 (d, 1H, J1
.4 Hz, H-3 ), 5.24 (t, 1H, J4
1033, 924 cm ; H NMR (200 MHz, CDCl ): d 8.62
(s, 1H, H-5), 6.17 (d, 1H, J
1H, J
5.32 (t, 1H, J
para
3
0
0
7
5
9
0
0
9.4 Hz, H-2 ),
0
0
9.3 Hz, H-1 ), 5.88 (t,
2 ;3
1 ;2
0
0
0
0
0
9.4 Hz, H-1 ), 5.33 (t, 1H, J
0
0
0
0
Hz, H-2 ), 5.44 (t, 1H, J
0
0
9.3 Hz, H-3 ),
;2
3 ;4
2 ;3
3 ;4
0
0
0
0
0
9.4 Hz, H-4 ), 4.29 (dd,
0
0
9.3 Hz, H-4 ), 4.09–4.06 (m, 1H, H-
;5
4 ;5

M. R. Couri et al. / Carbohydrate Research 342 (2007) 1096–1100
1099
0
0
0 0
2 ), 3.44–3.38 (m, 1H, H-6 a), 3.41 (s, 3H, OCH ), 2.85
3
5
), 4.31 (dd, 1H, J6
0
0
12.60, J
0
0
4.8 Hz, H-6 a), 4.17
a;6 b
6 a;5
0
13
0
13
(
(
(
(
d, 1H, H-6 b), 2.08, 2.04 (2s, 12H, CH CO); C NMR
50 MHz, CDCl ): d 170.67, 170.30, 169.38, 168.52
C@O), 153.68 (C-5), 86.84 (C-1 ), 75.35 (C-5 ), 73.11
C-3 ), 69.99 (C-2 ), 67.57 (C-4 ), 61.59 (C-6 ), 20.82,
0.69, 20.28 (CH CO). Anal. Calcd for C H N O :
C, 45.00; H, 5.00; N, 14.00. Found: C, 45.53; H, 5.01;
N, 13.81.
(t, 1H, J
0
0
¼ J
0
0
9.0 Hz, H-6 b);
C NMR
3
6 a;6 b
6 a;5
(50 MHz, CDCl ): d 143.96 (C-5), 137.98, 137.58,
3
3
0
0
137.06 (Cipso), 129.57, 128.70, 128.66, 128.25, 128.0,
0
0
0
0
0 0 0
127.91(Carom.), 99.15 (C-1 ), 75.91 (C-2 ), 74.90 (C-3 ),
0
0
2
74.12, 73.79, 73.09 (CH Ph), 67.45 (C-6 ), 65.76 (C-5 ),
3
15 20
4
9
2
0
59.21 (C-4 ), 56.03 (OCH3). Anal. Calcd for
C H N O : C, 67.44; H, 6.20; N, 10.85. Found: C,
2
9
32
4
5
6
7.64; H, 6.40; N, 10.83.
0
0
0
0
1
1
.8. 5-S-(2 ,3 ,4 ,6 -Tetra-O-acetyl-b-D-glucopyranosyl)-
0
0
0
0
-phenyl-5-thiotetrazole (6e)
1.11. 2-(Methyl 2 ,3 ,6 -tri-O-benzyl-4 -deoxy-a-D-
galactopyranos-4 -yl)tetrazole (7c)
0
20
9
Colourless oil, ½aꢀ ꢁ12.6 (c 1.05, CHCl ); lit. ꢁ13.0 (c
D
3
2
0
2
1
(
.3, CHCl ); IR (compression cell) m 2923, 1743, 1499,
Colourless oil; ½aꢀ +25.3 (c 2.15, CHCl ); IR (NaCl) m
3
D
3
ꢁ
1
1
ꢁ1
366, 1209, 1032, 911, 763, 689 cm
200 MHz, CDCl ): d 7.56–7.51 (sl, 5H, PhH), 5.78 (d,
10.1 Hz, H-1 ), 5.39–5.09 (m, 3H, H-2 , H-3 ,
H-4 ), 4.28 (dd, 1H, J6
.17–4.06 (m, 1H, H-6 b), 3.91 (ddd, 1H, J
2.1 Hz, H-5 ), 2.04 (br s, 12H, 4CH ); C NMR
50 MHz, CDCl ): d 170.71, 170.05, 169.74, 169.59
;
H NMR
2900, 1500, 1460, 1360, 1290, 1210, 1100, 750, 700 cm ;
1
H NMR (400 MHz, CDCl ): d 8.53 (s, 1H, H-5), 7.30–
3
3
0
0
0
0
1
H, J1
0
0
7.21 (m, 15H, PhH), 5.70 (dd, 1H, J 5.3, J 2.3 Hz, H-4 ),
4.79–4.18 (m, 6H, CH Ph), 4.84 (d, 1H, J
1 ), 4.46 (dd, 1H, J
H-3 , H-5 ), 3.41 (s, 3H, OCH ), 3.29 (dd, 1H, J
;2
0
0
0
0
12.5, J
0
0
4.8 Hz, H-6 a),
0
0
3.8 Hz, H-
a;6 b
0
6 a;5
2
1 ;2
0
0
0
10.0 Hz, H-2 ), 4.38–4.25 (m, 2H,
2 ;3
4
J5
(
(
8
6
0
0
9.8,
0
5
;6 b
0
13
0
0
0
0
0
0
9.4,
0
;4
3
3
6 a;6 b
0
J
0
0
5.6 Hz, H-6 a), 2.85 (t, 1H, J
0
0
7.8 Hz, H-6 b);
3
6 a;5
6 b;5
1
3
4C@O), 133.35 (C ), 130.71, 130.11, 124.25 (C
),
C NMR (50 MHz, CDCl ): d 152.80 (C-5), 138.41,
3
ipso
arom.
0
0
0
0
3.87 (C-1 ), 76.61 (C-5 ), 73.74 (C-3 ), 69.91 (C-2 ),
137.57, 137.41 (Cipso), 128.57, 128.54, 128.05, 128.0,
127.96 (Carom.), 99.35 (C-1 ), 75.65 (C-2 ), 74.82 (C-5 ),
7
63.14 (C-4 ), 55.87 (OCH3). Anal. Calcd for
C H N O : C, 67.44; H, 6.20; N, 10.85. Found: C,
0
0
0 0 0
7.91 (C-4 ), 61.62 (C-6 ), 20.84, 20.71 (CH CO).
3
0
0
4.16, 73.91, 72.61 (CH Ph), 68.22 (C-6 ), 66.47 (C-3 ),
2
0
0
0
0
0
1
.9. 2-(Methyl 2 ,3 ,6 -tri-O-benzyl-4 -deoxy-a-D-galacto-
pyranos-4 -yl)-5-phenyltetrazole (7a)
0
2
9
32
4
5
6
6.94; H, 6.43; N, 10.79.
2
D
0
Colourless oil; ½aꢀ +53.0 (c 1.70, CHCl ); IR (NaCl) m
3
ꢁ
1
0
0
0
0
3
100, 2950, 1540, 1510, 1460, 1210, 910, 740, 700 cm
H NMR (400 MHz, CDCl ): d 8.14–7.46 (m, 4H, PhH),
;
1.12. 5-S-(Methyl 2 ,3 ,6 -tri-O-benzyl-4 -deoxy-a-D-
galactopyranos-4 -yl)1-phenyl-5-thiotetrazole (7d)
1
0
3
7
.35–7.21 (m, 4H, PhH), 5.65 (dd, 1H, J 5.4, J 2.5 Hz,
0
0
20
D
H-4 ), 4.83 (d, 1H, J 3.8 Hz, H-1 ), 4.83 (d, 1H, J
Colourless oil; ½aꢀ +55.4 (c 1.89, CHCl ); IR (NaCl) m
1
,2
3
ꢁ
1 1
3100, 2800, 1600, 1500, 1460, 910, 750, 690 cm ; H
1
1.9 Hz, CH Ph), 4.75 (d, 1H, J 11.6 Hz, CH Ph), 4.65
2
2
(
d, 1H, J 11.9 Hz, CH Ph), 4.64 (d, 1H, J 11.6 Hz,
NMR (400 MHz, CDCl ): d 7.50–7.14 (m, 20H, PhH),
5.11–5.10 (br s, 1H, H-4 ), 4.78 (d, 1H, J 12.0 Hz,
2
3
0
0
CH Ph), 4.62 (dd, 1H, J
0
0
9.6 Hz, H-2 ), 4.38–4.27
2
2 ;3
0
0
(
m, 4H, H-3 , H-5 , 2CH Ph), 3.43 (s, 3H, OCH ),
CH Ph), 4.65 (d, 1H, J 10.9 Hz, CH Ph), 4.60–4.54
2
3
2
2
0
0
3
1
.32 (dd, 1H, J6
0
0
9.6, J
0
0
5.6 Hz, H-6 a), 2.98 (dd,
(m, 3H, CH Ph), 4.59 (d, 1H, J
(d, 1H, J 12.0 Hz, CH Ph), 4.38–4.40 (br t, 1H, H-5 ),
4.20 (dd, 1H, J
1H, J
0
0
3.8 Hz, H-1 ), 4.47
a;6 b
6 a;5
13
2
1 ;2
0
0
H, J6
0bꢁ5
7.5 Hz, H-6 b); C NMR (100 MHz, CDCl3):
2
0
d 164.84 (C-5), 138.38, 137.63, 137.48 (Cipso), 130.38,
0
0
9.8, J
0
0
4.1 Hz, H-3 ), 3.77 (dd,
5.5 Hz, H-6 a), 3.68 (dd, 1H, J
3 ;2
3 ;4
0
1
9
7
5
28.91, 128.54, 128.27, 127.98, 127.67, 127.17 (Carom.),
0
0
9.8, J
0
0
6 a;6 b
6 a;5
6 b;5
0
0
0
0
13
9.47 (C-1 ), 74.94 (C-5 ), 74.82 (C-2 ), 74.03, 73.87,
6.5 Hz, H-6 b), 3.39 (s, 3H, OCH ); C NMR (50 Hz,
3
0
0
0
2.50 (CH Ph), 68.39 (C-6 ), 66.60 (C-3 ), 63.24 (C-4 ),
CDCl ): d 154.22 (C-5), 138.19, 137.71, 137.57, 133.70
2
3
5.79 (OCH ). Anal. Calcd for C H N O : C, 52.94;
(Cipso), 130.04, 129.55, 128.37, 128.29, 127.98, 127.77,
3
35 36
4
5
0 0 0
H, 5.04; N, 11.76. Found: C, 52.94; H, 5.01; N, 11.83.
124.36 (Carom.), 98.85 (C-1 ), 77.15 (C-3 ), 76.39 (C-2 ),
0
0
7
3.67, 73.61, 72.77 (CH Ph), 70.24 (C-6 ), 67.95 (C-5 ),
2
0
0
0
0
0
1.10. 1-(Methyl 2 ,3 ,6 -tri-O-benzyl-4 -deoxy-a-D-
galactopyranos-4 -yl)tetrazole (7b)
55.51 (OCH3), 54.45 (C-4 ). Anal. Calcd for
0
C H N O S: C, 67.30; H, 5.77; N, 8.97. Found: C,
3
5
36
4
5
66.94; H, 5.48; N, 9.36.
2
D
0
Colourless oil; ½aꢀ +26.5 (c 1.20, CHCl ); IR (NaCl) m
3
ꢁ
1 1
900, 1500, 1460, 1360, 1200, 1110, 740, 700 cm ; H
2
NMR (400 MHz, CDCl ): d 8.50 (s, 1H, H-5), 7.35–
Acknowledgement
The authors thank the Conselho Nacional de Desen-
3
7
2
J1
.12 (m, 18H, PhH), 5.22 (dd, 1H, J
0
0
5.0, J
0
0
4
;5
4 ;3
0
.0 Hz, H-4 ), 4.79–4.18 (m, 6H, CH Ph), 4.78 (d, 1H,
2
0
0
0
0
3.8 Hz, H-1 ), 4.36–4.33 (m, 1H, H-5 ), 4.21 (dd,
volvimento Cientıfico e Tecnologico (CNPq) for finan-
cial support.
´
´
;2
0
1
H, J3
0
0
4.7 Hz, H-3 ), 3.92 (dd, 1H, J
0
0
10.0 Hz, H-
;4
2 ;3

1100
M. R. Couri et al. / Carbohydrate Research 342 (2007) 1096–1100
7. Cl e´ ophax, J.; Liagre, M.; Loupy, A.; Petit, A. Org. Process
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1