Cyclitols. XXXII. Cyclopentanepentols

1970 ◽  
Vol 23 (9) ◽  
pp. 1831 ◽  
Author(s):  
SJ Angyal ◽  
BM Luttrell
Keyword(s):  
Acetic Acid ◽  
Acid Hydrolysis ◽  
Strong Acid ◽  
Equilibrium Mixture ◽  
Relative Stabilities ◽  
Hydrolysis Of

Three cyclopentanepentols have been synthesized: the 1,2,4/3,5-isomer by acid hydrolysis of an anhydro-cyclopentanepentol, DL-1,2-anhydro-4,5-O-cyclohexylidene-1,2,3/4,5-cyclopentanepentol; the 1,2,3/4,5-isomer by deamination of (1,4/2,3,5)-5-amino-1,3-di-O-acetyl-2,3-O-cyclohexylidene-l,2,3,4-cycopentanetetrol; and the 1,2,3,4/5-isomer by solvolysis of two tetra-O-acetyl-O-tosylcyclopentanepentols. An equilibrium mixture of the three cyclopentanepentols was obtained by heating one of them with 95% acetic acid in the presence of a strong acid. The relative stabilities of the three isomers are in the order 1,2,4/3,5 > 1,2,3/4,5 > 1,2,3,4/5.

The chemistry of 2,1-benzisothiazoles. IX. The reaction of 3-chloro-substituted 2,1-benzisothiazoles with nucleophiles and the preparation of(2,1-Benzisothiazol-3-yl)acetic acid

1975 ◽  
Vol 28 (9) ◽  
pp. 2051 ◽  
Author(s):  
M Davis ◽  
E Homfeld ◽  
J McVicars ◽  
S Pogany
Keyword(s):  
Acetic Acid ◽  
Acid Hydrolysis ◽  
Auxin Analogue ◽  
Hydrolysis Of

3-Chloro-2,1-benzisothiazole (2; R = H, R? = Cl) and 3,5-dichloro-2,1- benzisothiazole (2;R,R? = Cl) react readily with nucleophiles, and yield 3-substituted products. Acid hydrolysis of one such product, ethyl (2,1-benzisothiazol-3-yl)cyanoacetate (2; R = H, R? = CH(CN)CO2Et),affords (2,1-benzisothiazol-3-yl)acetic acid (2; R = H, R? = CH2CO2H), an auxin analogue.

scholarly journals The effect of tunicamycin on the glycosylation of lactating-rabbit mammary glycoproteins

1979 ◽  
Vol 180 (3) ◽  
pp. 481-489 ◽  
Author(s):  
Brian K. Speake ◽  
David A. White
Keyword(s):  
Acid Hydrolysis ◽  
Paper Chromatography ◽  
Gel Electrophoresis ◽  
Protein Fraction ◽  
Polyacrylamide Gel Electrophoresis ◽  
Strong Acid ◽  
Polyacrylamide Gel ◽  
Control Value ◽  
Acid Hydrolysate ◽  
Hydrolysis Of

1. Tunicamycin inhibited the incorporation of d-[2-3H]mannose into dolichol-linked oligosaccharide and glycoprotein of lactating-rabbit mammary explants by approximately the same extent (approx. 30% of control value), suggesting that lipid-linked intermediates are involved in the mannosylation of mammary glycoproteins. 2. The incorporation of radioactivity from N-acetyl-d-[1-14C]glucosamine into dolichol-linked oligosaccharide was inhibited by tunicamycin to 32% of the control value, whereas the incorporation of the radiolabel into glycoprotein was only inhibited to 72% of the control value. 3. Considerable redistribution of label from N-acetylglucosamine to N-acetylgalactosamine was found to occur in the explants. In the presence of tunicamycin approx. 76% of the radioactivity incorporated into glycoprotein from N-acetyl-d-[1-14C]glucosamine was present as N-acetylgalactosamine, compared with approx. 61% in the absence of the inhibitor. Thus tunicamycin selectively inhibits the incorporation of N-acetylglucosamine into glycoprotein. 4. Radioactivity from N-acetyl-d-[1-14C]glucosamine was incorporated into a glycoprotein that was identified as casein by the use of a casein-specific antiserum, and also into a group of glycopolypeptides with apparent mol.wts. ranging between 40000 and 80000. N-Acetylgalactosamine was the only radioactive sugar released on strong-acid hydrolysis of the immunoprecipitated casein, whereas N-acetylglucosamine was the major radioactive residue present in the non-casein glycoproteins. Glucosamine and galactosamine were the only radiolabelled sugars detected by paper chromatography of the strong-acid hydrolysate of the protein fraction. 5. Tunicamycin inhibited the incorporation of radioactivity from N-acetyl-d-[1-14C]glucosamine into the glycopolypeptides with mol.wts. between 40000 and 80000 as described by polyacrylamide-gel electrophoresis, but did not affect the incorporation of label into casein. It appears that tunicamycin inhibits the incorporation of mannose and N-acetylglucosamine into a number of mammary glycoproteins by inhibiting the formation of lipid-linked intermediates, but does not inhibit the incorporation of N-acetylgalactosamine into casein.

Synthesis of 4-deoxydaunosamine and 4-deoxyristosamine

1980 ◽  
Vol 58 (16) ◽  
pp. 1751-1758 ◽  
Author(s):  
Hans H. Baer ◽  
Hanna R. Hanna
Keyword(s):  
Acetic Acid ◽  
Acid Hydrolysis ◽  
Sodium Borohydride ◽  
Catalytic Hydrogenation ◽  
Sodium Acetate ◽  
Amino Glycoside ◽  
Hydrolysis Of

Treatment of methyl 3,6-dideoxy-2,4-di-O-methylsulfonyl-3-nitro-α-L-glucopyranoside (2) with sodium acetate and acetic acid in acetone gave methyl 4-O-acetyl-2,3,6-trideoxy-3-nitro-α-L-erythro-hex-2-enopyranoside (3) as a kinetic product, and the 2-O-acetyl-3,4,6-trideoxy-3-nitro-α-L-threo-hex-3-eno isomer 4 as the thermodynamically preferred product. Treatment of 2 or 4 with sodium borohydride produced a separable mixture of methyl 2,3,4,6-tetradeoxy-3-nitro-α-L-threo-hexopyranoside (5) and its α-L-erythro epimer (6), the latter being convertible into the former by base-catalyzed epimerization. Acid hydrolysis of 5 and 6 afforded the corresponding free nitro sugars 7 and 8. Catalytic hydrogenation of 5 led to the corresponding amino glycoside, isolated as the acetate 9 or hydrochloride 10; similarly, 6 gave the epimeric amine which was isolated as its acetate 14 or picrate 15. N-Trifluoroacetylation of 9 provided the N-trifluoroacetyl glycoside 12 which was hydrolyzed to give a 49% yield (overall from 2) of 2,3,4,6-tetradeoxy-3-trifluoroacetamido-L-threo-hexose (4-deoxy-N-trifluoroacetyldaunosamine, 13). Analogously, 14 afforded the epimeric N-trifluoroacetyl glycoside 17 which was hydrolyzed to give a 28% overall yield of 2,3,4,6-tetradeoxy-3-trifluoroacetamido-L-erythro-hexose (4-deoxy-N-trifluoroacetylristosamine, 18).

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