A novel approach to the synthesis of 1,2-cis-glycopyranosides

Tetrahedron Letters,Vol.26,No.6,pp 807-808,1985 Printed in Great Britain

A NOVEL APPROACH

Francesco

Nicotra,

Dipartimento Sostanze Methyl

Summary:

TO THE SYNDESIS

Luigi Panza?

di Chimica

Organiche

OF 1,2-cis-GLYCOPYRANOSIDES

Fiamma Ronchetti,

Organica

Naturali

0040-4039/85 $3.00 + .OO 01985 Pergamon Press Ltd.

Giovanni

e Industriale

and Centro

de1 CNR, via Venezian

3,4,6-tri-O-benzyl-d-D-glucopyranoside

chemistry. tivated

synthesis

Differentglycoside-linking

component

1,2-cis-glycosides presence

of glycosides

and methyl

and a hydroxyl

component

from an activated

makes new synthetic

have been employed.'

methods

We wish here to report a novel approach

linkage

at C-2 in the proper

attack of the hydroxyl

according

in CHC13 mediate

(r.t., overnight) epoxides

chromatography. samples.

by reaction

and usual work-up

directly,

which-

"Guide Donegani"

3

into (2)-(2R,3R,UR)-6-methoxy-

Fellow,

were confirmed

June 1984-May

807

easily separated

without

1985.

acid(l.1

isolation

by flashmolar eq.)

of the inter-

e7 (35%) and methyl

easily separated

9

* Fondazione

nucleophilic

3

3,4,6-tri-0-benzyl-d-D-glucopyranoside

of these compounds

moiety and the

p

2) with m-chloroperbenzoic

afforded

$(20%),

of the type

with diphenyl(methoxymethyl)pho-

and its E isomer s6(20%),

of 4cO.2 muol)(scheme

The structures

oligo- and poly-

OH

and/or

of Suzuki and Mukaiyama,

1 4'5(40%)

3,4,6-tri-O-benzyl+D-mannopyranoside

occurring

2 -

was transformed,

6 and z, methyl -

of

On the other hand, the

OH ,\\'

P

1 -

Treatment

ac-

C-l.

>

chromatography.

the synthesis

(scheme l), by intramolecular

F

1,3,4-tribenzyloxy-5-hexen-2-01

of a glycosyl

such as 1, with the aglycone

steric relationship

to the procedure

task.

1

in carbohydrate

to which 1,2-cis-glycopyranosides

SCHEwEl

spine oxide, according

However,

of

welcome.

group at C-5 on an activated

2,3,5-Tri-0+enzyl-&arabinose2

problems

in various naturally

2 and/or 3 are formed from an open chain precursor substituent

Italy.

3,4,6-tri-O-benzyl-p-D-manno-

the combination

sugar is still a difficult

of the 1,2-cis-glycopyranosidic

saccharides

which utilize

di Studio per le

acid treatment

is one of the most important methods,

and Lucia Toma

21, 20133 Milano,

pyranoside were directly obtained by ;-chloroperbenzoic (Z)-(2R,3R,4R)-6-methoxy-l,3,4-tribenzyloxy-5-hexen-2-o1.

Stereospecific

Russo*

by silica gel

by comparison

with authentic-

808

SCHEME2

0Bt-l En0

m-CPBA

H

BnO

OCH3

\

% 0CH3

-9

nnv

4

OH

10 A small amount of

(El-(US,5R)-4,6-dibenzyloxy-5-hydroxy-2-hexenal

from the starting

Z-enolether,

These preliminary

results

as A, followed one-pot

References

indicate

(12%) was also obtained conditions.

of easily obtainable

cyclization

of 1,2-cis-glycopyranosides.

Work is in progress

acidic reaction

that the epoxidation

by the "in situ" spontaneous

synthesis

tractive.

owing to the slightly

lo

Z-enolethers

of the formed epoxides,

The above procedure

constitutes

seems therefore

an

quite at-

to improve and extend these results.

and Notes

1. H. Paulsen,

Angew. Chem. Int. Ed. Engl., 11, 155 (1982).

2. S. Tejima andH.J. Fletcher, 3. K. Suzuki and T. Mukaiyama, 4. Satisfactory

elemental

5. 4: oil,[@.]~"=-12.50(c

J. Orp. Chem., a,

2999 (1963).

Chem. Lett., 683 (1982).

analyses

and spectroscopic

1.2 in CHC13),

data were obtained

'H-NMR(CDC13,80MHz):&

6.15,

for all new compouns.

(d, lH, J=5.5Hz,

1.0 in CHC13), 'H-NMR(CDC13,80MHz):5 6. 5: m.p. 53-5U°C (from hexane),[d]i0=-320(c (d, lH, J5,6=13.5Hz, H-6); 4.83, (dd, lH, J5,6=13.5HZ, J4,5=9Hz, H-5). 7. 8: m.p. 87-88OC

(from hexane),[d]E'=

8. 2: oil,[D(]~"=-13.20( 9.

such

98O(c 1.0 in CHC13);

c 1.0 in CHC13);

(lit."

H-6).

6.45,

m.p. 87-89°C,[d]~o=1000)

(lit.12[d]$0=-10.20).

g was obtained from the known methyl 2-0-acetyl-3,4,6-tri-O-benzyl-o(-D-glucopyranosidel3 by CH30Na/CH30H hydrolysis. l4 2 was obtained from the known methyl 3,4,6-tri-0-benzylq-Dby NaBH4 reduction according to Shaban and Jeanloz.15 arabino-hexosidulosell

9.59, (d, lH, Jl 2=8Hz, H-l); 6.86, 10. lo: lH-NMR(CDC13,80MHz):5 H-3); 6.30, (ddd, lH, J1,2=8Hz, J2,3=16Hz,'J2,4=0.8Hz, H-2). 11. G. Ekborg,

B. Lindberg

12. V.R. Srivastava

and J. w,

and C. Schuerch,

13. S. Koto, N. Morishima, 1092 (1982).

(dd, lH, J2 3=16Hz,

Acta Chem. Stand., 26! 3287 (1972). Tetrahedron

R. Kawahara,

Lett., 35, 3269 (1979).

K., Ishikawa

and S. Zen, Bull. Chem. SOC. Jpn., 55,

14. N.K. Kochetkov, B.A. Dmitriev, N.N. Malysheva, A.Ya. Chernyak,E.M. and V.I. Torgov, Carbohydr. Res., 45, 283 (1975). 15. M.A.E.

Shaban and R.W. Jeanloz,

J3,4=5.5Hz,

Carbohydr.

(Received in UK 30 November 1984)

Res., 52, 103 (1976).

Klinow, N.E. Bayramova