Intramolecular Nucleophilic Displacement Research Articles

Evidence for rate-limiting deprotonation of a spiro-Meisenheimer intermediate during Smiles' rearrangement of 2-(p-nitrophenoxy)ethylamine

Kinetic studies of intramolecular nucleophilic aromatic displacement of alkoxide ion by the amino group in 2-(p-nitrophenoxy)ethylamine support a mechanism whereby, at low base concentrations, the rate of Smiles' rearrangement is dependent upon the rate of general base-catalysed deprotonation of a spiro-Meisenheimer intermediate; at high base concentrations the base independent rate of formation of the Meisenheimer intermediate becomes rate limiting.

Nucleophilic displacement of aromatic fluorine. Part IV. Quinolinoquinolines and benzochromenoquinolines

AbstractThe title compounds were obtained by facile intramolecular nucleophilic displacement of aromatic fluorine from 4‐(2‐fluorophenyl)quinolines bearing substituents such as a carboxamide, carboxaldehyde, carboxaldoxime or a hydroxymethyl group in the 3‐position.

Nucleophilic displacement of aromatic fluorine, Part III, indoloquinolines and benzofuranoquinolines

AbstractVariously substituted indolo[2,3‐c]quinolines, benzofurano[2,3‐c]quinolines and their positional isomers indolo[3,2‐c]quinolines and benzofurano[3,2‐c]quinolines respectively, were prepared from both indole and quinoline derivatives by intramolecular nucleophilic displacement of aromatic fluorine. The formation of an indolo[2,3‐d]benzazepine was also observed.

Intramolecular participation of the amide group in the hydrolysis of p-nitrophenyl N-(bromoacetyl) anthranilate

The rate of hydrolysis of p-nitrophenyl N-(bromoacetyl) anthranilate (Ib) has been measured in aqueous solution between pH 1 and 6.5 has been found to increase linearly with pH at pH higher than 3. An abnormally large apparent alkaline rate constant of 3.8 × 10 6 M −1 sec −1 has been determined. Intramolecular nucleophilic displacement by the amide group at the carbonyl carbon of the ester occurred and a cyclic intermediate was formed. This intermediate has been detected by direct isolation and by measurements of the proton release accompanying the reaction. The rates of hydrolysis of analogous derivatives (IIb-IIIb-IV), for which this intramolecular assistance was not possible, were slower by a factor of about 5 × 10 5. Such an example of intramolecular catalysis may be useful for a better understanding of the enzymatic catalysis.

A new heterocyclisation reaction leading to cinnolin-4(1H)-one derivatives

2-Nitrophenacylidene phenylhydrazones (2) undergo base-catalysed cyclisation by intramolecular nucleophilic displacement of the nitro-group by the ortho-side-chain, providing an efficient general route to 3-substituted 1-phenylcinnolin-4(1H)-ones (3).

Degenerate interconversions of sulfonium ions involving intramolecular nucleophilic displacement by neighboring sulfide sulfur. Question of an intermediate in the SN2 displacement

Degenerate interconversions of sulfonium ions involving intramolecular nucleophilic displacement by neighboring sulfide sulfur. Question of an intermediate in the SN2 displacement

The chemistry of nitro-compounds. Part III. The intramolecular nucleophilic displacement of aromatic nitro-groups by carbanions

Heating α-(N-methyl-N-o-nitrobenzoylamino)phenylacetonitrile (1a) with sodium ethoxide in ethanol affords moderate yields of 2-methyl-3-oxo-1-phenylisoindoline-1-carboxamide (3a) and benzoic acid. Similar treatment of the N-benzyl and N-phenyl o-nitrobenzamide derivatives (1b and c) yields, in addition to benzoic acid, separable mixtures of the 3-oxoisoindoline-1-carbonitriles (2b and c), the derived amides (3b and c), and the 3-phenyliso-indolin-1-ones (4b and c). Isoindolinone formation by direct intramolecular displacement of the ortho-nitro-group by the cyanobenzyl carbanion generated in the side-chain is indicated by the conversion of the amides (1a–c) in hot ethanolic sodium carbonate in high yield into the 3-oxoisoindoline-1-carbonitriles (2a–c). In addition to benzoic acid, the latter reactions respectively afford o-azidobenzoic acid (12), benzaldehyde o-carboxy-phenylhydrazone (13), and azobenzene-2-carboxylic acid (14) as by-products. The substituted benzamides (6), (7a and b), and (8a and b) are unaffected by ethanolic sodium carbonate. In contrast, the 2-nitro-5-methyl compound (6) and the 2-chloro-5-nitro-derivative (8c) are respectively converted by heating with ethanolic sodium ethoxide and ethanolic sodium carbonate into the 5-methyl- and 5-nitro-3-oxo-1,2-diphenylisoindoline-1-carbonitriles (9a and b). The mechanisms of the reactions are discussed.

Pyrolysis of potassium 2′-fluoro- and 2′-bromo-biphenyl-2-carboxylate

The smooth intramolecular nucleophilic displacement which occurs when potassium 2′-nitrobiphenyl-2-carboxylate is heated to give 3,4-benzocoumarin also occurs, in poorer yield, when the nitro-group is replaced by fluorine and bromine, but not by cyanide. The related reaction to give seven-membered cyclic products does not occur.

Methyl 2,6-Anhydro-3,4-di-O-methyl-α-D-mannoside. An Intramolecular Nucleophilic Displacement of Mesylate with Inversion

Methyl 2,6-Anhydro-3,4-di-O-methyl-α-D-mannoside. An Intramolecular Nucleophilic Displacement of Mesylate with Inversion

11β‐Hydroxy‐progesteron‐18‐säure‐lacton und die WALDEN'sche Umkehrung am Kohlenstoffatom 11 bei 18‐oxygenierten Steroiden. Über Steroide, 178. Mitteilung

The intramolecular nucleophilic displacement with WALDEN inversion of the llα‐tosyloxy group in 18,20‐lactones of the pregnane series is described. Depending upon the reaction conditions 18,11,β‐lactones or orthoester derivatives are obtained.