METHYLATION OF SUGAR DITHIOACETALS: IV. D-XYLOSE DIETHYL DITHIOACETAL

1962 ◽  
Vol 40 (10) ◽  
pp. 1899-1902 ◽  
Author(s):  
G. G. S. Dutton ◽  
Y. Tanaka
Keyword(s):  
Methyl Iodide ◽  
Methyl Ether ◽  
Silver Oxide ◽  
Partial Methylation ◽  
Tetrahydrofuran Solution

Partial methylation of D-xylose diethyl dithioacetal in tetrahydrofuran with methyl iodide and silver oxide yielded 2-, 3-, and 5-O-methyl-D-xyloses in the ratio of 20:10:1. The poly-O-methylated components were not examined. The 2-O-methyl-D-xylose was identified as the crystalline sugar and the 3-O-methyl ether as the phenylosazone and p-bromophenylosazone. An alternative preparation of the dithioacetal in tetrahydrofuran solution is described.

STUDIES OF REACTIONS RELATING TO CARBOHYDRATES AND POLYSACCHARIDES.: XXVIII. THE STRUCTURE OF ISOPROPYLIDENE GLYCEROL

1930 ◽  
Vol 2 (3) ◽  
pp. 214-217 ◽  
Author(s):  
Harold Hibbert ◽  
J. G. Morazain
Keyword(s):  
Methyl Iodide ◽  
Methyl Ether ◽  
Copper Sulphate ◽  
Silver Oxide ◽  
Condensation Product ◽  
Neutral Medium ◽  
Physico Chemical ◽  
Isopropylidene Glycerol

Isopropylidene glycerol, prepared in neutral medium by the action of anhydrous copper sulphate as condensing agent, was methylated with silver oxide and methyl iodide; the product yielded only glycerol α-methyl ether on hydrolysis, thus proving the absence of any six-membered ketal in the condensation product of glycerol and acetone.The properties of both glycerol α- and β-methyl ethers have been carefully redetermined.A table of the isomeric acetals and ketals summarising their physico-chemical constants is given, in view of their usefulness as "type compounds" in investigations relating to fats, carbohydrates and polysaccharides.

METHYLATION OF SUGAR DITHIOACETALS: V. D-MANNOSE DIETHYL DITHIOACETAL

1963 ◽  
Vol 41 (10) ◽  
pp. 2500-2503 ◽  
Author(s):  
G. G. S. Dutton ◽  
Y. Tanaka
Keyword(s):  
Methyl Iodide ◽  
Silver Oxide ◽  
The Other ◽  
Partial Methylation

Partial methylation of D-mannose diethyl dithioacetal in tetrahydrofuran with methyl iodide and silver oxide yielded 2-, 3-, and 6-O-methyl-D-mannose in the ratio of 12:1:1, respectively. The major component, 2-O-methyl-D-mannose, was characterized as the phenyl-hydrazone and the other isomers identified by electrophoresis. The Mg values of these mono-O-methyl ethers were recorded.

ipso Nitration. XXIII. Reactions of cyclohexadiene adducts from nitration of 4-ethyltoluene in acetic anhydride

1981 ◽  
Vol 59 (15) ◽  
pp. 2314-2327 ◽  
Author(s):  
Alfred Fischer ◽  
George N. Henderson
Keyword(s):  
Sulfuric Acid ◽  
Acetic Anhydride ◽  
Methyl Iodide ◽  
Methyl Ether ◽  
Potassium Hydroxide ◽  
Silver Oxide ◽  
Aluminum Hydride ◽  
Trifluoroacetic Anhydride ◽  
Aqueous Methanol

The diastereoisomers of 4-ethyl-1-methyl-4-nitrocyclohexa-2,5-dienyl acetate (1) and 1-ethyl-4-methyl-4-nitrocyclohexa-2,5-dienyl acetate (2) are stereospecifically reduced to the corresponding nitrocyclohexadienols with aluminum hydride. Each dienol is stereospecifically methylated to the corresponding methyl ether with methyl iodide, silver oxide, and potassium hydroxide. Acid-catalysed solvolysis of the acetates 1 and 2 results in the substitution of the acetate moiety by other nucleophiles and these reactions are not stereospecific. The products of rearomatization of dienyl acetates, dienols, and dienyl methyl ethers depend on the acidity and ionizing power of the solvents and are readily explained in terms of reactions involving a nitrocyclohexadienyl cation or acetoxy- (hydroxy-, methoxy-)cyclohexadienyl cation as key intermediates. In the 4-acetoxy-4-alkylcyclohexadienyl cation 1,2-migration of the acetoxyl group is more rapid than alkyl migration, but 1,2-alkyl migration is faster than migration of the hydroxyl or methoxyl groups in the corresponding cations. 1-Ethyl-4-methoxy-4-methylcyclohexa-2,5-dien-1-ol and 4-ethyl-3-nitrotoluene are significant minor products in the solvolysis of 1-ethyl-4-methyl-4-nitrocyclohexa-2,5-dien-1-ol in aqueous methanol. Nitration of p-ethyltoluene in the presence of sulfuric acid or in trifluoroacetic anhydride gives a mixture of 4-ethyl-2-nitro- and 4-ethyl-3-nitrotoluene in a 2:1 ratio.

Lithiation of bridgehead positions in 3,6-bridged piperazine-2,5-diones

1982 ◽  
Vol 35 (11) ◽  
pp. 2289 ◽  
Author(s):  
FW Eastwood ◽  
D Gunawardana ◽  
GT Wernert
Keyword(s):  
Carbonyl Group ◽  
Methyl Iodide ◽  
Methyl Ether ◽  
Sodium Methoxide ◽  
Inductive Effect ◽  
Amide Nitrogen

2,5-Dimethyl-2,5 diazabicyclo[2,2,2]octane-3,6-dione can be lithiated at the 1,4 (bridgehead) positions with 2 equiv. of t-butyllithium at -78� and deuterated with D2O (Do, 11.2; Dl, 56.1 ; D2, 30.1%). With butyllithium and methyl iodide the 1,2,5-trimethyl and 1,2,4,5-tetramethyl derivatives are obtained. Treatment of dimethyl 2,6-diaminoheptanedioate dihydrochloride with sodium methoxide in boiling butanol gives 6,8-diazabicyclo[3,2,2]nonane-7,9-dione in 62% yield. N-Methylation of this compound yields 6,8-dimethyl-6,8-diazabicyclo[3,2,2]nonane-7,9-dione which can similarly be lithiated at the 1,5 (bridgehead) positions and deuterated with D2O (Do, 5.6; Dl, 70.8; D2, 23.6%). Lithiation with butyllithium and reaction with methyl iodide, benzyl iodide or bromomethyl methyl ether gives mono-and di-alkylated products at the 1,5-positions. The ability to lithiate the bridgehead positions in these compounds is attributed primarily to a combination of the inductive effect of the carbonyl group and dipole stabilization by the amide nitrogen.

METHYLATION OF SUGAR MERCAPTALS: II. L-ARABINOSE DIETHYL MERCAPTAL

1961 ◽  
Vol 39 (9) ◽  
pp. 1797-1800 ◽  
Author(s):  
G. G. S. Dutton ◽  
Y. Tanaka
Keyword(s):  
Methyl Iodide ◽  
Silver Oxide

Methylation of L-arabinose diethyl mercaptal in tetrahydrofuran with methyl iodide and silver oxide yielded mainly 2-O-methyl-L-arabinose and a trace of 5-O-methyl-L-arabinose. The identity of the major component was inferred by its behavior on electrophoresis and confirmed by the preparation of the crystalline amide. The polymethylated components were not examined. 2-O-Methyl-L-arabono-γ-lactone, previously known as a sirup, has now been obtained crystalline.

N-Methylamino acids in peptide synthesis. VII. Studies on the enantiomeric purity of N-methylamino acids prepared by various procedures

1977 ◽  
Vol 55 (5) ◽  
pp. 916-921 ◽  
Author(s):  
S. T. Cheung ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acid ◽  
Methyl Iodide ◽  
Peptide Synthesis ◽  
Liquid Ammonia ◽  
Silver Oxide ◽  
Sodium Hydride ◽  
Enantiomeric Purity ◽  
Amino Acid Analyzer ◽  
Pure Compounds ◽  
Optically Pure

The enantiomeric purity of N-methylamino acids and their derivatives obtained by various procedures has been examined by analysis with an amino-acid analyzer of the diastereomeric lysyl dipeptides formed by coupling them with a lysyl derivative. N-Benzyloxycarbonyl, and N-tert-butyloxycarbonyl,N-methylamino acids obtained by methylation of the parent derivative using sodium hydride and methyl iodide, and N-methylamino acids obtained by methylation of the p-toluenesulfonylamino acid followed by treatment with sodium in liquid ammonia, are optically pure. Compounds obtained by other procedures which include reductive alkylations or the use of silver oxide – methyl iodide are generally not optically pure.

Partial methylation of methyl α-D- and β-D-threofuranoside

1990 ◽  
Vol 55 (7) ◽  
pp. 1777-1782 ◽  
Author(s):  
Jiří Jarý ◽  
Miroslav Marek ◽  
Ivan Raich
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Relative Rate ◽  
Hydroxyl Groups ◽  
Partial Methylation ◽  
Methylation Rate ◽  
Consecutive Reactions ◽  
Relative Rate Constants ◽  
The Individual

The methylation rate of hydroxyl groups of the title glycosides I and II has been studied in their reaction with methyl iodide and sodium hydroxide in acetonitrile. From the relative rate constants determined for the side and consecutive reactions taking place the differences in methylation rate of the individual hydroxyl groups have been deduced and are discussed from the standpoint of possible steric and polar effects.

Quinones and quinone methides. VIII. Oxidation products of the screwworm chemosterilant, 2,4-Bis(1,1-dimethylethyl)-6-(4-methoxyphenylmethyl)phenol

1981 ◽  
Vol 34 (8) ◽  
pp. 1633 ◽  
Author(s):  
L Jurd ◽  
RY Wong
Keyword(s):  
Single Crystal ◽  
Methyl Ether ◽  
Title Compound ◽  
Silver Oxide ◽  
Complex Mixture ◽  
Oxidation Products ◽  
X Ray Diffraction ◽  
Quinone Methides ◽  
X Ray ◽  
Benzylic Alcohol

The title compound is oxidized by silver oxide in acetone to a complex mixture of products, including the benzophenone derivative (7), a benzylic alcohol, isolated as its methyl ether (15), and two spiro cyclohexadienone benzopyran dimers (17) and (19). A colourless dimer was shown by single-crystal X-ray diffraction measurements to be a 2,3- dihydrobenzofuran derivative (22).

A revision of the structures proposed for the melicope extractives, melicopol and methylmelicopol

1973 ◽  
Vol 26 (11) ◽  
pp. 2459 ◽  
Author(s):  
BS Balgir ◽  
LN Mander ◽  
STK Mander
Keyword(s):  
Methyl Ether ◽  
Partial Methylation ◽  
Ether Derivative

2,4,6-Trihydroxybenzoic acid was converted by partial methylation, formylation, and then reduction into methyl 2-hydroxy-3-hydroxymethyl- 4,6-dimethoxybenzoate (5) which proved different from dimethyldegeranylmelicopol. Methyl 6-geranyloxy-2-hydroxy-3- hydroxymethyl-4-methoxybenzoate (4), its neryl analogue (7), and methyl 4-geranyloxy-2-hydroxy-3-hydroxymethyl-6-methoxybenzoate (21) were prepared similarly but all were different from methylmelicopol. From a re-investigation of earlier work, melicopol and methylmelicopol were assigned new structures, 6?-geranyloxy-2,2?,4?-tri-hydroxy-3?- methoxyacetophenone (31) and its 4?-methyl ether derivative (24), respectively. Dimethyldegeranylmelicopol, 2,6?-dihydroxy-2?,3?,4?- trimethoxyacetophenone (25), was prepared from antiarol (28) and acetoxyacetonitrile.

Partial methylation of methyl 4,6-dideoxy-α- and β-L-ribo-hexopyranosides

1984 ◽  
Vol 49 (9) ◽  
pp. 2130-2140 ◽  
Author(s):  
Karel Kefurt ◽  
Zdeňka Kefurtová ◽  
Jiří Jarý
Keyword(s):  
Gas Chromatography ◽  
Ir Spectra ◽  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Hydroxyl Groups ◽  
View Point ◽  
Partial Methylation ◽  
H Nmr ◽  
Analogous Data

Anomeric methyl 4,6-dideoxy-L-ribo-hexopyranosides I and V, prepared from aldose IX, were etherified with methyl iodide in acetonitrile in the presence of sodium hydroxide. From the products of partial methylation methyl 4,6-dideoxy-2-O-methyl-α-L-ribo-hexopyranoside (II) and methyl 4,6-dideoxy-2,3-di-O-methyl-α-L-ribo-hexopyranoside (IV), or methyl 4,6-dideoxy-2-O-methyl-β-D-ribo-hexopyranoside (VI) and methyl 4,6-dideoxy-2,3-O-methyl-β-L-ribo-hexopyranoside (VIII), respectively, were isolated. The substances were identified by 1H NMR, mass and IR spectra and comparison with standards. The course of etherification of glycosides I and V was checked by gas chromatography and the reactivity of the hydroxyl groups was evaluated by determining the rate constants or their ratios. The observed values were compared with analogous data for other isomers of methyl 4,6-dideoxyhexopyranosides and discussed from the view-point of sterical and polar influence on the reactivity of both their hydroxylic groups.

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