Pyridines dialkyl

In sharp contrast to the behavior observed when the three dithio-acetals aforementioned are treated with p-toluenesulfonyl chloride in pyridine, dialkyl dithioacetals of D-arabinose, treated under the same conditions, are converted into the corresponding 5-p-toluene-sulfonates, generally isolable crystalline in high yield.72 This remarkable difference has been interpreted72" on conformational grounds the D-arabinose dithioacetals are stable in the extended, planar zigzag conformation, whereas the other three examples experience some destabilization in the extended form, because of parallel 1,3-interactions.726 Furthermore, the transition state for closure of the 2,5-anhydro ring would be quite strained in the D-arabinose series, but not in the other three.72"... 

The diazines react with alkyl halides to give mono-quaternary salts, though somewhat less readily than comparable pyridines. Dialkylation cannot be achieved with simple alkyl halides, however the more reactive trialkyloxonium tetrafluoroborates do convert aU three systems into di-quatemary salts. ... 

Pyridine Dialkyl thiophosphites from phosphorochloridites s. 16, 632 in dimethylacetamide without pyridine cf. J. Heterocyclic Chem. 3, 14 (1966) C,H,N (R0)2PC1 (RO)jPSH R. Ratz and A. D. Bliss,... 

Diorgano Sulfites. Symmetrical or mixed dialkyl sulfites ate prepared by the stepwise reaction of thionyl chloride either with two molecules of an alcohol or with stoichiometric quantities of two alcohols in pyridine (105). 

Cychc sulfites can be prepared from the glycols and thionyl chloride in the presence of pyridine this route is analogous to the preparation of dialkyl... 

Esters derived from the primary alcohols are the most stable and those derived from the tertiary alcohols are the least stable. The decomposition temperature is lower in polar solvents, eg, dimethyl sulfoxide (DMSO), with decomposition occurring at 20°C for esters derived from the tertiary alcohols (38). Esters of benzyl xanthic acid yield stilbenes on heating, and those from neopentyl alcohols thermally rearrange to the corresponding dithiol esters (39,40). The dialkyl xanthate esters catalytically rearrange to the dithiol esters with conventional Lewis acids or trifluoroacetic acid (41,42). The esters are also catalytically rearranged to the dithiolesters by pyridine Ai-oxide catalysts (43) ... 

Isothiazolo[3,4-d]pyridin-4(5H)-one, 3,6-dialkyl-applications, 6, 644 2H-Isothiazolo[2,3-a]pyrimidine synthesis, 6, 640 Isothiazolo[4,3-d]pyrimidine synthesis... 

Pyridine, 6-cyano-l,2-dihydro-thermal dimerization, 2, 370 Pyridine, 2-cyanomethyl-tautomerism, 2, 159 Pyridine, 4-cyanomethyl-tautomerism, 2, 159 Pyridine, 2-cyano-2,3,4,5-tetrahydro-metallation, 2, 387 Pyridine, 2,5-diacetyl-ipso substitution, 2, 301 Pyridine, 3,5-diacetyl-l,4-dihydro-Hantzsch synthesis, 2, 482 Pyridine, 4-dialkylamino-as acylation catalysts, 2, 34 Pyridine, 2,2-dialkyl-l,2-dihydro-... 

Wahrend N,N -disubstituierte Harnstoffe von Lithiumalanat nicht angegriffen werden, erhalt man mit Natriumboranat in siedendem Pyridin mit mittleren Ausbeuten die entsprechenden N,N -disubstituierten Formamidine. N,N -Dialkyl-harnstoffe liefern die besten Ausbeuten, N,N -Diaryl-harnstoffe die schlechtesten3. 

Reaction of pyridines with dialkyl acetylenedicarboxylates in the presence of isocyanates in dry CH2C12 at room temperature produced 1-substituted 2-oxo-l,9a-dihydro-2/7-pyrido[l,2-tf]pyrimidine-3,4-dicarboxylates <2004TL1803>. One-pot, three-component synthesis of 1-substituted 2-oxo-l,llb-dihydro-2//-pyrimido[2,l- ]iso-quinoline-3,4-dicarboxylates and 4-(3-chloro-4-methylphenyl)-3-oxo-4,4a-dihydro-3/7-pyrimido[l,2-tf]quinoline-l,2-dicarboxylate was realized by the reaction of isoquinoline and quinoline with isocyanates and dialkyl acetylenedicarboxylates <2004S861>. Diastereomeric mixtures of l-tosyl-2-aryl-l,llb-dihydro-2/7-pyrimido[2,Ttf]isoquinoline-3,4-dicarboxylates were obtained from isoquinoline, iV-tosyl-benzaldehyde imines, and DMAD <2002OL3575>. 

Bouvier, C. Cote, G. Cierpiszewski, R. Szymanowski, J. Influence of salting-out effects temperature and the chemical structure of the extractant on the rate of copper(II) extraction from chloride media with dialkyl pyridine dicarboxylates. Solvent Extr. Ion Exch. 1998, 16, 1465-1492. 

Preparation of diethyl pyridine-2-phosphonate — Reaction of an N-methoxy pyridinium salt with a dialkyl phosphite salt... 

Katritzky, A.R., Keay, J.G., and Sammes, M.P., Regiospecific synthesis of dialkyl pyridin-4-yl, quinolin-4-yl, and isoquinolin-l-yl-phosphonates, /. Chem. 

One can prepare derivatives of 4 that contain a weakly-bound ligand L, such as a pyridine or a dialkyl sulfide. These compounds show no... 

Cyclization of dialkyl Ar-(4-substituted or 2-substituted 3-thienyl)amino-methylenemalonates in phosphoryl chloride yielded the corresponding 3-substituted 7-chlorothieno[3,2-6]pyridine-6-carboxylate (89MIP1), or l-substituted-4-chlorothieno[3,4-b]pyridine-5-carboxylate, respectively, [89JCR(S)196],... 

Dialkyl N-(benzoxazin-4-yl)methylenemalonates and their optically active forms (1728) were prepared in the reaction of the appropriate pheny-laminomethylenemalonate (1727), triphenylphosphine, and diethyl azodi-carboxylate in THF at -20°C (89EUP3228I5). The hydroxyl group of racemic and optically active phenylaminomethylenemalonates (1727) were tosylated with p-toluenesulfonyl chloride in pyridine, and the products were cyclized by heating in DMF at 80°C in the presence of potassium carbonate and a catalytic amount of 18-crown-6-ether to give 1728 (89EUP322815). 

Potentially tautomeric pyrimidines and purines are /V-alkylated under two-phase conditions, using tetra-n-butylammonium bromide or Aliquat as the catalyst [75-77], Alkylation of, for example, uracil, thiamine, and cytosine yield the 1-mono-and 1,3-dialkylated derivatives [77-81]. Theobromine and other xanthines are alkylated at N1 and/or at N3, but adenine is preferentially alkylated at N9 (70-80%), with smaller amounts of the N3-alkylated derivative (20-25%), under the basic two-phase conditions [76]. These observations should be compared with the preferential alkylation at N3 under neutral conditions. The procedure is of importance in the derivatization of nucleic acids and it has been developed for the /V-alkylation of nucleosides and nucleotides using haloalkanes or trialkyl phosphates in the presence of tetra-n-butylammonium fluoride [80], Under analogous conditions, pyrimidine nucleosides are O-acylated [79]. The catalysed alkylation reactions have been extended to the glycosidation of pyrrolo[2,3-r/]pyrimidines, pyrrolo[3,2-c]pyridines, and pyrazolo[3,4-r/]pyrimidines (e.g. Scheme 5.20) [e.g. 82-88] as a route to potentially biologically active azapurine analogues. 

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