scholarly journals Trityl derivatives of cellobiose. IV. Studies on the relative reactivities of the secondary hydroxyl groups in 6,6'-di-O-tritylcellobiose and methyl 6,6'-di-O-trityl-.BETA.-cellobioside by selective acetylation.

1981 ◽  
Vol 29 (10) ◽  
pp. 2776-2784 ◽  
Author(s):  
KYOKO KOIZUMI ◽  
TOSHIKO UTAMURA
Keyword(s):  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Derivatives Of

scholarly journals SYNTHESIS OF 1,2;3,4-DI-O-ISOPROPYLIDENE-6- O-[4-(1H-AZOL-1-YLMETHYL) PHENYL]- ¯-D-GALACTOPYRANOSE AND 1,2,3,4-TETRA-O-ACETYL-6- O-[4-(1H-AZOL-1- YLMETHYL)PHENYL]-¯-D-GLUCOPYRANOSE

2017 ◽  
Vol 17 (5) ◽  
pp. 122-128
Author(s):  
Z.P. Belousova ◽  
P.P. Purygin ◽  
A.P. Tyurin
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Primary Hydroxyl ◽  
Derivatives Of

Derivatives of D-galactose and D-glucose substituted for the primary hydroxyl group, which contain an aglycone azolylmethylphenyl fragments (for imidazole, 1,2,4-triazole, benzimidazole and benzotriazole) has been synthesized. Toprotect the secondary hydroxyl groups of monosaccharides acetyl and isopropylidene groups were used.

Kinetic benzylidenation. Part II. Rearrangement of the kinetic products from benzylidenation of aldose diethyl dithioacetals

1986 ◽  
Vol 64 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
T. Bruce Grindley ◽  
Srihari Kusuma
Keyword(s):  
Room Temperature ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
High Yields ◽  
Derivatives Of

Terminal five-membered O-benzylidene derivatives of aldose diethyl dithioacetals can be rearranged at room temperature in N,N-dimethylformamide, often in high yields. Derivatives with the arabino configuration for their three terminal secondary hydroxyl groups, i.e. D-glucose, D-mannose, and D-arabinose derivatives, rearranged to structures containing terminal six-membered O-benzylidene rings. 4,5-O-Benzylidene-D-ribose diethyl dithioacetal rearranged chiefly to the 2,4 isomer, which was obtained by crystallization. Chromatography yielded some of the 3,5 isomer. 5,6-O-Benzylidene-D-galactose diethyl dithioacetal rearranged to a mixture of the two 4,5-O-benzylidene diastereomers, contrary to predictions based on the Hann–Hudson rules. A revised set of rules for acetal stability in N,N-dimethylformamide has been formulated. D-arabinose and D-ribose diethyl dithioacetal were shown to react with α, α-dimethoxytoluene under rearrangement conditions to give the products noted above in good yields.

The role of secondary alcoholic groups of D-galacturonan in its degradation with exo-D-galacturonanase

1980 ◽  
Vol 45 (2) ◽  
pp. 427-434 ◽  
Author(s):  
Kveta Heinrichová ◽  
Rudolf Kohn
Keyword(s):  
Acetyl Derivative ◽  
Competitive Inhibitor ◽  
Hydroxyl Groups ◽  
Pectic Acid ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
The Individual ◽  
Degradation Degree ◽  
Derivatives Of

The effect of exo-D-galacturonanase from carrot on O-acetyl derivatives of pectic acid of variousacetylation degree was studied. Substitution of hydroxyl groups at C(2) and C(3) of D-galactopyranuronic acid units influences the initial rate of degradation, degree of degradation and its maximum rate, the differences being found also in the time of limit degradations of the individual O-acetyl derivatives. Value of the apparent Michaelis constant increases with increase of substitution and value of Vmax changes. O-Acetyl derivatives act as a competitive inhibitor of degradation of D-galacturonan. The extent of the inhibition effect depends on the degree of substitution. The only product of enzymic reaction is D-galactopyranuronic acid, what indicates that no degradation of the terminal substituted unit of O-acetyl derivative of pectic acid takes place. Substitution of hydroxyl groups influences the affinity of the enzyme towards the modified substrate. The results let us presume that hydroxyl groups at C(2) and C(3) of galacturonic unit of pectic acid are essential for formation of the enzyme-substrate complex.

Regioselectivity among six secondary hydroxyl groups: selective acylation of the least reactive hydroxyl groups of inositol

2012 ◽  
Vol 48 (18) ◽  
pp. 2448 ◽  
Author(s):  
Amol M. Vibhute ◽  
Adiyala Vidyasagar ◽  
Saritha Sarala ◽  
Kana M. Sureshan
Keyword(s):  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Selective Acylation

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

scholarly journals Characteristic Flavonoids from Acacia burkittii and A. Acuminata Heartwoods and their Differential Cytotoxicit to Normal and Leukemia Cells

2009 ◽  
Vol 4 (1) ◽  
pp. 1934578X0900400
Author(s):  
Mary H. Grace ◽  
George R. Wilson ◽  
Fayez E. Kandil ◽  
Eugene Dimitriadis ◽  
Robert M. Coates
Keyword(s):  
Cell Line ◽  
Relative Concentration ◽  
Hydroxyl Groups ◽  
L1210 Cells ◽  
Green Monkey ◽  
Bioassay Guided Fractionation ◽  
Acetone Extracts ◽  
Derivatives Of ◽  
Hplc Analyses ◽  
Mouse Lymphoma

Bioassay-guided fractionation of extracts from Acacia burkittii and A. acuminata heartwoods against an L1210 (mouse lymphoma) cell line led to the isolation of two flavan-3,4-diols, melacacidin (1) and isomelacacidin (2), and three flavonoids, 3,7,8,3′,4′-pentahydroxyflavone (3), 7,8,3′,4′-tetrahydroxyflavanone (4) and 3,7,8,3′,4′-pentahydroxyflavanone (5). HPLC analyses (280 nm) of the 70% acetone extracts of the two plants showed different profiles in terms of the relative concentration of the five identified compounds. When tested against L1210, compounds 1 and 2 were the most active, giving ID50 values of 2.5 and 4.5 μg/mL, respectively. The lower activity of the other isolated compounds indicated the importance of the 3,4-hydroxyl groups for the cytotoxic activity of these flavonoids. The isolated compounds were either non-toxic or had very low toxicities against the “normal” CV-1 cell line (green monkey kidney cells). The O-methyl and O-acetyl derivatives of these compounds were inactive. Ten commercially available phenolic compounds (6-15) were also tested for their activity against both CV-1 and L1210 cell lines. Flavan-3,4-diols 1 and 2 were more cytotoxic to L1210 cells than all tested compounds, including catechin and epicatechin, the most abundant flavan-3-ols in many fruits and vegetable.

Conversion of hydroxyl groups into bromo groups in carbohydrates with inversion of configuration

1981 ◽  
Vol 59 (2) ◽  
pp. 339-343 ◽  
Author(s):  
Björn Classon ◽  
Per J. Garegg ◽  
Bertil Samuelsson
Keyword(s):  
Elevated Temperature ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Reaction Proceeds ◽  
One Step ◽  
High Yields

A novel reagent system is described for the efficient, one-step transformation of hydroxyl groups in carbohydrates to bromodeoxy groups. The reaction proceeds with inversion of configuration. The reagent system consists of triphenylphosphine, tribromoimidazole, and imidazole in toluene at elevated temperature. The carbohydrate need not be soluble in toluene. The examples given include substitution of isolated primary and secondary hydroxyl groups in otherwise protected carbohydrates as well as disubstitution involving one primary and one secondary position in hexopyranosides. High yields are obtained in the replacement of hydroxyl by bromine in the 2-position of 3,4,6-protected methyl α-D-gluco- and -mannopyranosides.

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