Original scientific paper

Glycosyl Esters of Amino Acids. VI. Synthesis and Properties of Unprotected Glucosyl and Glucuronic Esters of Glycine and Alanine

D. Keglević ; Tracer Laboratory, Institute »Ruder Boskovic«, 41000 Zagreb, Croatia, Yugoslavia
Dj. Ljevaković ; Tracer Laboratory, Institute »Ruder Boskovic«, 41000 Zagreb, Croatia, Yugoslavia
S. Valenteković ; Tracer Laboratory, Institute »Ruder Boskovic«, 41000 Zagreb, Croatia, Yugoslavia

Abstract

Treatment of 1-0-(N-tert-butyloxycarbonyl-glycyl- and -L-
alanyl)-~-n-glucopyranose s with trifluoroacetic acid at - 10 °C,
led to a clean removal of the BOC-protecting group without
affecting the C-1 ester linkage. The corresponding unprotected
glucosyl esters I and II were isolated as trifluoroacetate salts
and characterized by phyisical methods and by conversion into the
known N-acetyl derivatives III and IV. In the gluc;uronic ester
series, conditions for selective deprotection of the sugar moiety were
examined with benzyl 2,3,4-tri-O-benzyl-1-0-(N-acetyl-L-alanyland
-1-0-(N -tert-butyloxycarbonyl-L-alanyl)-o-glucopyranuronates
(V and VI). Catalytic hydrogenation of the ~ anomers of V
and VI gave the corresponding 1-0-acylaminoacyl-~-n-glucopyranuronic
acids VII and VIII; for characterization purposes, VIII
was converted into methyl 2,3,4-tri-0-acetyl-1-0-(N-tert-butyloxycarbonyl-
L-alanyl)-~-n-glucopyranuronate (IX-~), prepared
also by an alternative route. Complete deprotection of VIII afforded
1-0-(L-alanyl)-~-o-glucopyranuronic acid trifluoroacetate salt
(X) which was also obtained by catalytic hydrogenation of
benzyl 2,3,4-tri-O-benzyl-1-0-(N -benzyloxycarbonyl-L-alanyl)-~-D-
glucopyranuronate (XI) in the presence of trifluoroacetic acid.
Selective deprotection of the hydroxyl and carboxyl functions in
the a anomer of VI by catalytic hydrogenation, led to a concomitant
1-+ 2 acyl migration; the rearrangement product was
characterized as methyl l ,3,4-tri-O-acetyl-2-0-(N-tert-butyloxycarbonyl-
L-alanyl)-o-glucopyranuronaie (XII), highly enriched in
the a anomer.

Keywords

Hrčak ID:

196826

URI

https://hrcak.srce.hr/196826

Publication date:

1.11.1974.

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