Unusual Nucleophilic Substitution Research Articles

Fluorinated NH-iminophosphonates in synthesis of biorelevant α-aminophosphonic acids derivatives

Reactions of (poly)fluoroalkylated NH-iminophosphonates with nitromethane, trimethylsilylcyanide, and diphenylphosphine oxide lead to respective fluorinated β-nitro-α-aminophosphonates, α-cyano-α-aminophosphonates, and heminal bisphosphonates. Reaction with 3-aminocrotonitrile 5 proceds at the β-position of enamine. In the case of α-imino chlorodifluoroethylphosphonate 1c the reaction is accompanied by an unusual nucleophilic substitution of the chlorine atom in CF2Cl group with the formation of pyrroline bearing a difluoromethylated aminophosphonate moiety

ChemInform Abstract: A Short Preparation of Pyrroloquinoxalinones via a Cascade Reaction of N‐Aryl‐5‐alkylamino‐2‐nitrosoanilines with Methyl 2‐Cyanoalkanoates: Unexpected Direction of Nucleophilic Substitution of Hydrogen.

AbstractThe bisheteroannulation to produce the title compounds (III) involves condensation of a cyanoester anion with the nitroso group of substrates (I), unusual nucleophilic substitution of hydrogen with a second anion, and double intramolecular acylation.

A Short Preparation of Pyrroloquinoxalinones via a Cascade Reaction of N-Aryl-5-alkylamino-2-nitrosoanilines with Methyl 2-Cyanoalkanoates: Unexpected Direction of Nucleophilic Substitution of Hydrogen

N -Aryl-2-nitrosoanilines possessing 5-alkylamino groups undergo a bisheteroannulation reaction with anions of 2-cyanoalkanecarboxylates resulting in pyrroloquinoxalinone derivatives. The cascade reaction involves condensation of the cyanoester anions with the nitroso group, unusual nucleophilic substitution of hydrogen in the nitrosoaniline-derived intermediate with the second carbanion molecule, and double intramolecular acylation of the amino functions.

Nucleophilic substitution at the anomeric position of 1,2- O-isopropylidenefuranose derivatives. A novel stereoselective synthesis of cyclic phosphates analogous to cAMP

1,2- O-Isopropylidenefuranose derivatives were treated with various nucleophiles in the presence of either BF 3·OEt 2 or trimethylsilyl trifluoromethanesulfonate (TMSOTf) leading to substitution products in a regio- and stereoselective manner. In particular, nucleophilic substitution of 1,2- O-isopropylidenefuranose derivatives when treated with allyltrimethylsilane was controlled by steric and electronic factors (similar to Woerpel’s stereoelectronic model). On the other hand, when 1,2- O-isopropylidenefuranose derivatives were treated with trimethylsilane, in the presence of bis- O-trimethylsilyl-5-iodouracil or bis- O-trimethylsilyl-thymidine, substitution products were generated in high regio- and stereoselectivities via an unusual nucleophilic substitution with opening of the furanose ring. Based on these results, a stereoselective method for the synthesis of neutral cyclic phosphates analogous to cAMP was developed.

Selective Ring‐Opening of Nonactivated Amino Aziridines by Thiols and Unusual Nucleophilic Substitution of a Dibenzylamino Group.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Selective Ring-Opening of Nonactivated Amino Aziridines by Thiols and Unusual Nucleophilic Substitution of a Dibenzylamino Group

[Reaction: see text]. The reaction of chiral 2-(1-aminoalkyl)aziridines 1 with different thiols, in the presence of BF3*Et2O, is reported. The obtained products were dependent on the structure of the starting amino aziridines 1. Thus, enantiopure (2S,3S)-2-(alkylthio)alkane-1,3-diamines 2 were obtained from aziridines with C-2 substituents with lower steric congestion and partially racemized (2S,3S)-2,3-bis(alkylthio)alkan-1-amines 3 (ee = 56-66%) from aziridines with larger C-2 subtituents. In both cases, the opening of the nonactivated aziridine ring at C-2 took place with retention of configuration and proceeded with regio- and stereoselectivity at C-2. In the synthesis of 3, 2 equiv of thiol reacts with 1 and the opening of aziridine ring at C-2 was followed by an unusual displacement of the dibenzylamino group by a second equivalent of thiol. The regiochemistry and relative configuration of compounds 3 was established by single-crystal X-ray analysis. A mechanism is proposed to explain the results obtained.

Unusual nucleophilic substitution in the nitrophthalimide series

The reactions of 3- and 4-nitrophthalimides with hydroxylamine in aqueous alcohol media were studied. A mixture of 3-amino-4-nitro- and 4-amino-5-nitrophthalimides is formed in the case of 4-nitrosubstituted derivative, whereas 3,6-dihydroxyphthalimide is unexpectedly found to be the main product of the reaction of 4-nitrosubstituted derivative. A possible mechanism of the transformation was suggested.

Unusual Substitution of –SCH3by –OH in 9,10-Dihydrophenanthrene

The unusual nucleophilic substitution of methylthio by a hydroxyl group in the presence of alkali and dimethylformamide in the synthesis of methyl 1-(4-chlorophenyl)-3-hydroxy-7-methoxy-9,10-dihydrophenanthrene-4-carboxylate, C23H19ClO4, has been confirmed by single-crystal X-ray structure determination.

Unusual nucleophilic substitution reaction of tetrachloropyridine N-oxide

The reaction between 2,3,5,6-tetrachloropyridine N-oxide and sodium dimethyldithiocarbamate in acetone forms 1-[6-(3′,5′,6′-trichloropyrid-2′-ylthio)-3,5-dichloropyrid-2-ylthio]propan-2-one as the main product.

6-nitro-2,3-dipiperidinoquinoxaline: Its unexpected formation from 2-chloro-7-nitroquinozaline.

Abstract Excess piperidine and 2-chloro-7-nitroquinoxaline 1 in diethyl ether give large amounts of the unexpected disubstitution product 6-nitro-2,3-di-piperidinoquinoxaline 3 . The mechanism of this very unusual nucleophilic substitution of hydrogen is suggested to involve the oxidation of the dipiperidino-dihydroquinoxaline 10 by dissolved oxygen.

The structure of leudrin, and the nucleophilic substitution of its primary hydroxy group by bromine

Leudrin (1a), present in some genera of the Proteaceae, is a pyrocatechol analogue of the phenolic spirobislactone leucodrin (1b). It has been characterized as its highly crystalline ar-dimethyl ether (1c). Leudrin can be re-formed from this derivative by demethylation with boron tribromide; under the conditions of the demethylation, it also undergoes unusual nucleophilic substitution to afford 11-bromo-11-deoxyleudrin (5a). The latter derivative affords leudrin after reaction with silver nitrate.

An unusual nucleophilic substitution on an aromatic substrate. Reaction of 2,5-dimethyl-3,4-dinitrothiophen with sodium arenethiolates in methanol

The reaction between 2,5-dimethyl-3,4-dinitrothiophen and sodium arenethiolates gives aryl 2-(5-methyl-4-nitro)thenyl sulphides via an unusual nucleophilic substitution, as shown by the 1H n.m.r. spectra of the isolated sulphides and the corresponding sulphones.