Catalysis by α-substituted pyridines in the hydrolysis of aryl acetates and acetic anhydride

1983 ◽  
Vol 36 (10) ◽  
pp. 1951 ◽  
Author(s):  
LW Deady ◽  
WL Finlayson
Keyword(s):  
Acetic Anhydride ◽  
Nucleophilic Catalysis ◽  
Substituted Pyridines ◽  
Hydrolysis Of

Results for the hydrolysis of p-nitrophenyl acetate, 2,4-dinitrophenyl acetate and acetic anhydride, catalysed by various substituted 2-amino- and 2-methyl-pyridines, are reported. The results seem consistent with nucleophilic catalysis throughout, contrary to some literature reports.

Vinylogous nucleophilic catalysis. Tertiary amine promoted hydrolysis of 1-alkene-1-sulfonyl chlorides

1984 ◽  
Vol 62 (10) ◽  
pp. 1977-1995 ◽  
Author(s):  
James Frederick King ◽  
John Henry Hillhouse ◽  
Stanisław Skonieczny
Keyword(s):  
Sulfonyl Chloride ◽  
Tertiary Amines ◽  
Nucleophilic Catalysis ◽  
Product Composition ◽  
Similar Product ◽  
Substituted Pyridines ◽  
Solvent Isotope ◽  
Zwitterionic Intermediate ◽  
Hydrolysis Of ◽  
Concerted Reaction

We present evidence that the reactions of ethenesulfonyl chloride (1) and trans-1-propene-1-sulfonyl chloride (3) with water in the presence of pyridine, trimethylamine, and a number of other tertiary amines proceed primarily by way of an initial vinylogous substitution reaction to form the cationic sulfene, [Formula: see text], which subsequently reacts with water either by addition (and deprotonation) to form the betaine [Formula: see text], or by vinylogous substitution (and deprotonation) to give the alkenesulfonate anion, [Formula: see text] (R = H or CH3). Formation of the latter represents the first well-supported example of vinylogous nucleophilic catalysis. These conclusions are drawn from kinetic and product composition observations, including (a) α-monodeuteration in the betaine and lack of deuteration of the ethenesulfonate [Formula: see text] from the reaction in D2O, (b) rate lowerings of up to 2000-fold for 2- (and 6-) substituted pyridines from those expected from Brønsted-type relationships shown by "unhindered" pyridine bases, (c) lack of a kinetic solvent isotope effect in the reaction of 1 with 3-cyanopyridine, (d) a lower rate of reaction of 3 vs. 1 not directly correlated with product composition, and (e) formation of similar product mixtures from either 1 or Pyr+CH2CH2SO2Cl Cl− (18a) with aqueous pyridine. For the initial formation of the sulfene, [Formula: see text], the available evidence does not distinguish between a two-step mechanism via an intermediate zwitterion and a closely related concerted reaction, but for the further reaction of the sulfene a process involving a zwitterionic intermediate common to both products is favoured. For the reaction of 1 or 3 in the absence of tertiary amines evidence is presented for a direct displacement on sulfur mechanism leading to the alkenesulfonate anion, plus a small proportion (up to 15%) of formation of the 2-hydroxy-1-alkanesulfonate anion by way of the sulfene HOCHRCH=SO2 (R = H or CH3).

The aminolysis of p-nitrophenyl acetate by aminopyridines. Mechanisms in aqueous and aprotic solvents

1980 ◽  
Vol 33 (11) ◽  
pp. 2441 ◽  
Author(s):  
LW Deady ◽  
WL Finlayson
Keyword(s):  
Acetic Anhydride ◽  
Dimethyl Sulfoxide ◽  
Amino Nitrogen ◽  
Base Catalysis ◽  
Aprotic Solvents ◽  
Nucleophilic Catalysis ◽  
General Base ◽  
Amide Formation ◽  
Ring Nitrogen ◽  
Hydrolysis Of

In dimethyl sulfoxide, the aminolysis of p-nitrophenyl acetate by aminopyridines results in amide formation, through nucleophilic catalysis by the ring nitrogen for 4-aminopyridine, but by direct amino nitrogen attack for 2-aminopyridine (as previously found for acetic anhydride). In water, the aminopyridines catalyse the hydrolysis of the ester (unlike aniline, which still gives acetanilide). In general, this occurs by nucleophilic catalysis by the ring nitrogen. Even 4-amino-2- methylpyridine reacts by this route (though 2-picoline does not) and, of the compounds studied, only for 2-amino- 6-methylpyridine does general base catalysis occur instead. Reasons for these mechanism changes are discussed.

Synthesis of conjugates of 1-(carboxymethyl)cytosine and 1-(5-O-carboxymethyl-β-D-arabinofuranosyl)cytosine with proteins

1979 ◽  
Vol 44 (10) ◽  
pp. 3023-3032 ◽  
Author(s):  
Helmut Pischel ◽  
Antonín Holý ◽  
Günther Wagner
Keyword(s):  
Human Serum Albumin ◽  
Acetic Anhydride ◽  
Serum Albumin ◽  
Human Serum ◽  
Activated Esters ◽  
Hydrolysis Of

1-(Carboxymethyl)cytosine (Ia), 1-(5-O-carboxymethyl-β-D-arabinofuranosyl)cytosine (IIa) and 5'-O-carboxylmethylcytidine (IIIa) were transformed by treatment with acetic anhydride and 4-dimethylaminopyridine to the peracetyl derivatives Ib-IIIb. These products reacted with p-nitrophenol in the presence of N, N'-dicyclohexylcarbodiimide to give the activated esters Ic-IIIc which on reaction with ammonia, dimethylamine or 2-aminoethanol afforded the corresponding carboxamides Id-IIId, IIe,f. Reactions of Ic and IIc with human serum albumin and bovine γ-globulin at pH 9.2, followed by hydrolysis of the N- or O-acetyl groups at pH 9.5, gave 50% up to 64% yields of the respective conjugates Ig, IIg and Ih, IIh.

NMR study of the synthesis of17O-enriched acetic acid by hydrolysis of acetic anhydride with17O-enriched water

2003 ◽  
Vol 41 (11) ◽  
pp. 959-961 ◽  
Author(s):  
Heidi M. Hultman ◽  
Kristina Djanashvili ◽  
Joop A. Peters
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Nmr Study ◽  
Hydrolysis Of

Synthetic application of cyclobutanes V. α-Carbalkoxymethylation of α, β-unsaturated ketones

1977 ◽  
Vol 55 (5) ◽  
pp. 822-830 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Patrick Chi-Lin Yao
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Acetic Anhydride ◽  
Potassium Carbonate ◽  
Alkyl Iodide ◽  
Keto Ester ◽  
Unsaturated Ketones ◽  
Synthetic Application ◽  
Hydrolysis Of ◽  
Villiger Oxidation

Two general methods for α-carbalkoxymethylation of both enolizable and nonenolizable (towards the γ-position) α,β-unsaturated ketones have been developed. Method A involves three synthetic steps: photocycloaddition of the starting enone to 1,1-dimethoxyethylene, hydrolysis–oxidation of the adduct with acetic acid and 30% hydrogen peroxide, and O-alkylation of the resulting mixture of lactone and acid using anhydrous potassium carbonate and an alkyl iodide, e.g., 13 → 17 → 21 + 22 → 23. Method B differs from method A in the means of securing the required cyclobutanone intermediate. Thus, photocycloaddition of 13 to vinyl acetate followed by hydrolysis of the adduct gave two epimeric keto alcohols 39 whose oxidation with dimethyl sulfoxide and acetic anhydride afforded diketone 40. Baeyer–Villiger oxidation of 40 followed by methylation of the products 21 and 22 completed the overall α-carbomethoxymethylation process to give keto ester 23.

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