The Synthesis of 4-Hydroxydithiocoumarins: A Case of Unusual Tautomer Stability

1987 ◽  
Vol 40 (7) ◽  
pp. 1179 ◽  
Author(s):  
JE Andersonmckay ◽  
AJ Liepa
Keyword(s):  
Carbon Disulfide ◽  
Sodium Hydride ◽  
Strong Acid ◽  
Sodium Perborate ◽  
Alkyl Derivatives ◽  
Acid Anhydrides

2'-Chloroacetophenones react with carbon disulfide in the presence of sodium hydride to form 4-hydroxydithiocoumarin anions. Kinetic protonation provides the 4-hydroxydithiocoumarins which can be tautomerized to 2-mercapto-1-thiochromones by treatment with strong acid. � Both tautomers are quite stable and do not readily interconvert. Alkylation of either 4-hydroxydithiocoumarin or 2-mercapto-1-thiochromone provides S-alkyl derivatives exclusively while acylation with acid anhydrides gives mixtures of O- and S-acyl products. Oxidation with sodium perborate yields the exocyclic monosulfoxide while m-chloroperbenzoic acid gives the exocyclic sulfone.

Isopropyl N-Arylmalonamates. Synthesis, Structure, Conformation and Reactions with Carbon Disulfide

2006 ◽  
Vol 71 (1) ◽  
pp. 59-76 ◽  
Author(s):  
Wolf-Dieter Rudorf ◽  
Dušan Loos ◽  
Joanna Wybraniec ◽  
Naďa Prónayová ◽  
Ryszard Gawinecki ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Carbon Disulfide ◽  
Aromatic Amines ◽  
Alkylating Agent ◽  
Sodium Hydride ◽  
Open Chain ◽  
Ketene Dithioacetals ◽  
Correlation Analyses ◽  
C Nmr

Acylation of aromatic amines 1 with diisopropyl malonate (2) leads to a mixture of isopropyl N-arylmalonamates 3 and malonanilides 4. The reaction of 3 with carbon disulfide in the presence of sodium hydride gives disodium salts 5. Treatment of 5 with an alkylating agent yields the open-chain or cyclic ketene dithioacetals 6, 7 or 8. The molecular structure, hydrogen bonding and preferential conformation of the isopropyl N-arylmalonamates 3, 6 and 7 were investigated using correlation analyses of IR, 13C NMR and AM1 semiempirical data.

Synthesis of Some 2'-C-Alkyl Derivatives of 9-(2-Phosphonomethoxyethyl)adenine and Related Compounds

1994 ◽  
Vol 59 (9) ◽  
pp. 2069-2094 ◽  
Author(s):  
Hana Dvořáková ◽  
Antonín Holý ◽  
Ivan Rosenberg
Keyword(s):  
Reaction Pathway ◽  
Sodium Hydride ◽  
Amino Group ◽  
Trimethylsilyl Derivative ◽  
Phosphonic Acids ◽  
Alkyl Derivatives ◽  
Hydrolysis Of ◽  
Trifluoromethyl Derivative ◽  
Derivatives Of ◽  
Related Compounds

To study the effect of β-substitution in 2'-alkyl derivatives of 9-(2-phosphonomethoxyethyl)adenine (Ia) on the antiviral activity or group specificity, these derivatives were synthesized. 9-(2-Hydroxyalkyl)adenines VIII were prepared by alkylation of adenine with suitably substituted oxiranes XIII or 2-hydroxyalkyl p-toluenesulfonates IV and VI. After protection of the adenine amino group by benzoylation (compounds IX) or amidine formation (compounds X), the intermediates were alkylated with diisopropyl p-toluenesulfonyloxymethanephosphonate (XI) in the presence of sodium hydride. After deprotection, the obtained phosphonate diesters XII were converted into phosphonic acids I by transsilylation and hydrolysis. This synthetic scheme was used for the preparation of ethyl (Ie), propyl (If), 2-propyl (Ig), 2-methylpropyl (Ih), cyclopropyl (Ii), cyclohexyl (Ij), benzyl (Ik) and phenyl (Il) derivatives. The 2'-trifluoromethyl derivative XXIIa was prepared analogously from 9-(2-hydroxy-3,3,3-trifluoropropyl)adenine (XXa), obtained by alkylation of adenine sodium salt with 2-hydroxy-3,3,3-trifluoropropyl bromide. 2'-Trimethylsilyl derivative XIXa was obtained by alkylation of adenine with 2-diisopropylphosphonomethoxy-3-(4-toluenesulfonyloxy)propyltrimethylsilane (XVII) followed by transsilylation and hydrolysis of diester XVIIIa. 2,6-Diaminopurine derivatives XVIIId and XXIIb were obtained analogously. 9-(3-Phosphonomethoxybutyl)adenine (XXVIII) and 9-(2-methyl-2-phosphonomethoxypropyl)adenine (XXXV) were prepared from the corresponding hydroxy derivatives XXVIb and XXXII, respectively, by the same reaction pathway as derivatives I.

Reaktionen von 2-Methyl-1H-benzimidazol mit Schwefelkohlenstoff und Phenylisothiocyanat. Kristall- und Molekülstruktur von 1,1′ -Carbonothioyl-bis(2-methyl-1H-benzimidazol) und 2-Methyl-1-(ethoxycarbonylmethylthio-phenylimino)-1H-benzimidazol / Reactions of 2-Methyl-1 H-benzimidazole with Carbon Disulfide and Phenyl Isothiocyanate. Molecular and Crystal Structures of 1,1′-Carbonothioyl-bis(2-methyl-1 H-benzimidazole) and 2-Methyl-1-(ethoxycarbonylmethylthio-phenylimino)-1 H-benzimidazole

1995 ◽  
Vol 50 (5) ◽  
pp. 837-843 ◽  
Author(s):  
Wolfgang Dölling ◽  
Helmut Hartungb ◽  
Matthias Biedermann
Keyword(s):  
Crystal Structures ◽  
Methyl Iodide ◽  
Carbon Disulfide ◽  
Alkylating Agent ◽  
Sodium Hydride ◽  
Phenyl Isothiocyanate ◽  
Reaction Products ◽  
X Ray ◽  
Molecular And Crystal Structures

Abstract 2-Methyl-1 H-benzimidazole 1 reacts in the presence of two equivalents of sodium hydride in dry DMSO with carbon disulfide to methyl 2-methylbenzimidazole-1-dithiocarboxylate 3 using methyl iodide as alkylating agent, whereas using 1,2-dibromoethane 1,1′-carbonothioyl bis(2-methyl-1 H-benzimidazole) 5 is formed. Compound 1 reacts with phenyl isothiocyanate in the presence of one equivalent of sodium hydride in dry DMF after alkylation to 2-methyl-1-( alkylthio-phenylimino)-1 H-benzimidazoles 6a, 6b. Reaction products 5 and 6b have been identified and structurally characterized by X-ray analysis.

Reductions

2008 ◽  
Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum
Keyword(s):  
Organic Synthesis ◽  
Carbon Disulfide ◽  
Room Temperature ◽  
Sodium Hydride ◽  
Hydrogen Gas ◽  
Gas Evolution ◽  
Reaction Sequence ◽  
Tributyltin Hydride ◽  
Aqueous Layer ◽  
Crushed Ice

The Barton deoxygenation (or Barton–McCombie deoxygenation) is a two-step reaction sequence for the reduction of an alcohol to an alkane. The alcohol is first converted to a methyl xanthate or thioimidazoyl carbamate. Then, the xanthate or thioimidazoyl carbamate is reduced with a tin hydride reagent under radical conditions to afford the alkane. Trialkylsilanes have also been used as the hydride source. Reviews: (a) McCombie, S. W. In Comprehensive Organic Synthesis; Trost, B. M.; Fleming, I., Eds.; Pergamon Press: Oxford, U. K., 1991; Vol. 8, Chapter 4.2: Reduction of Saturated Alcohols and Amines to Alkanes, pp. 818–824. (b) Crich, D.; Quintero, L. Chem. Rev. 1989, 89, 1413–1432. To a solution of the â-hydroxy-N-methyl-O-methylamide (0.272 g, 1.55 mol) in tetrahydrofuran (THF) (30 mL) were added carbon disulfide (6.75 mL, 112 mmol) and iodomethane (6.70 mL, 108 mmol) at 0 °C. The mixture was stirred at this temperature for 0.25 h, and then sodium hydride (60% suspension in mineral, 136.3 mg, 3.4 mmol) was added. After 20 min at 0 °C, the reaction was quenched by slow addition to 60 g of crushed ice. (Caution: hydrogen gas evolution!). The mixture was raised to room temperature and separated, and the aqueous layer was extracted with CH2Cl2 (4 × 15 mL). The combined organic extracts were dried (Na2SO4</aub>), concentrated in vacuo, and purified (SiO2, 5% EtOAc in hexanes) to afford 0.354 g (86%) of the xanthate. To a solution of the xanthate (2.95 g, 11.1 mmol) in toluene (100 mL) was added tributyltin hydride (15.2 mL, 56.6 mmol) and 2,2´-azobisisobutyronitrile (AIBN, 0.109 g, 0.664 mmol). The reaction mixture was then heated to reflux for 1 h. The mixture was cooled, concentrated in vacuo, and purified (SiO2, 100% hexanes to remove tin byproducts, followed by 10% EtOAc in hexanes to elute product) to afford 1.69 g (96%) of the N-methyl-O-methylamide.

Synthesis of uracils substituted in the position 5 or 5,6 with alkyl or cycloalkyl groups and their UV spectra

1979 ◽  
Vol 44 (8) ◽  
pp. 2426-2437 ◽  
Author(s):  
Ivan Bašnák ◽  
Jiří Farkaš
Keyword(s):  
Carbon Atom ◽  
Alkaline Medium ◽  
Cyclopropane Ring ◽  
Sodium Hydride ◽  
Chloroacetic Acid ◽  
Ethyl Formate ◽  
Uv Spectra ◽  
Lithium Diisopropylamide ◽  
Subsequent Reaction ◽  
Alkyl Derivatives

Lithium diisopropylamide used as a base in the Claisen condensation of alkylacetates and cycloalkylacetates with ethyl formate or acetate gave substantially higher yields of β-oxo esters than sodium hydride or sodium bis(trimethylsilyl)amide. Reaction of the obtained β-oxo esters with thiourea in an alkaline medium afforded 5- or 5,6-disubstituted 2-thiouracils Ib-XIIb which on subsequent reaction with chloroacetic acid were transformed into the uracil derivatives Ia-XIIa. The UV spectra of uracils substituted in the positions 5 or 6 with cyclopropane ring exhibit in the 265 nm region bathochromic shifts of 1 to 6.5 nm as compared with the correspondingly substituted alkyl derivatives. A qualitative correlation of these shifts with the electron deficit on the carbon atom bonded to the cyclopropane ring was attempted.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Improvement in the Fock test for determining the reactivity of dissolving pulp

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 21-26 ◽  
Author(s):  
CHAO TIAN ◽  
LINQIANG ZHENG ◽  
QINGXIAN MIAO ◽  
CHRIS NASH ◽  
CHUNYU CAO ◽  
...  
Keyword(s):  
Moisture Content ◽  
Sodium Hydroxide ◽  
Constant Temperature ◽  
Carbon Disulfide ◽  
Testing Procedure ◽  
Dissolving Pulp ◽  
Water Bath ◽  
Testing Conditions ◽  
Pulp Sample ◽  
Fock Reactivity

The Fock test is widely used for assessing the reactivity of dissolving pulp. The objective of this study was to modify the method to improve the repeatability of the test. Various parameters that affect the repeatability of the Fock test were investigated. The results showed that Fock reactivity is dependent on testing conditions affecting the xanthation between cellulose and carbon disulfide, such as the moisture content of the pulp sample, sodium hydroxide (NaOH) concentration, xanthation temperature, carbon disulfide dosage, and xanthation time. The repeatability of the test was significantly improved using the following modified testing procedure: air dried sample in the constant temperature/humidity room, xanthation temperature of 66°F (19°C) in a water bath, xanthation time of 3 h, NaOH concentration of 9% (w/w), and 1.3 mL carbon disulfide.

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