Showing papers on "Intramolecular reaction published in 1970"
TL;DR: This article showed that the methyl transfer I II (see scheme 1) does not follow the formally appealing mechanism of the endocyclic SN-process III; the reaction proceeds intermolecularly under all conditions investigated.
Abstract: Fig. 1 illustrates a definition of the terms endocyclic and exocyclic SN-reactions, referring to intramolecular nucleophilic substitution processes that occur by an SN2-analogous mechanism.
Crossing experiments show that the methyl transfer I II (see scheme 1) does not follow the formally appealing mechanism of the endocyclic SN-process III; the reaction proceeds intermolecularly under all conditions investigated. Kinetic measurements indicate that the methyl transfer XI XII (see scheme 3) occurs in a similar fashion. This behaviour is believed to follow from the preference of tetrahedral carbon for backside attack by the nucleophile in SN2-reactions.
The general experience, according to which intramolecular reaction paths over cyclic transition states with ring sizes of 5 or 6 are preferred to their intermolecular counterparts, is not to be extrapolated to SN2-reactions at tetrahedral carbon.
110 citations
TL;DR: In this paper, the reaction of α, N-diphenylnitrone with acetic anhydride has been investigated using homogeneously 18O-labeled acetic-anhydride.
14 citations
TL;DR: The isolation of this intermediate was identified as an oxazolinone deriving from the intramolecular reaction of the specific substrates, in agreement with the influence of the oxAZolinone on the hydrolysis of the parent Naacyl amino acid amide when utilized as specific substrate for a-chymotrypsin.
12 citations
TL;DR: In this paper, the trans-sulphenylation reactions are best interpreted in terms of a series of intermolecular substitution reactions at the sulphensyl sulphur atom.
Abstract: Treatment of 3-hydroxy-1-methylpropyl 2-nitrobenzenesulphenate with sodium hydride in dioxan gives a mixture of 3-hydroxybutyl 2-nitrobenzenesulphenate, starting material, butane-1,3-diyl bis-(2-nitrobenzenesulphenate), and decomposition products. Under similar conditions 3-hydroxybutyl 2-nitrobenzenesulphenate gives only decomposition products. The trans-sulphenylation reactions are best interpreted in terms of a series of intermolecular substitution reactions at the sulphenyl sulphur atom rather than in terms of an intramolecular reaction, which would involve a non-linear transition state for the reaction at the sulphenyl sulphur atom.
3 citations
TL;DR: The rearrangement of N-(α-substituted benzyl)-NN-dimethylanilinium hydroxides (I) to give the ortho- and para-substantituted NN-dimethyl-ylinium (II) and (III) has been studied in this paper.
Abstract: The rearrangement of N-(α-substituted benzyl)-NN-dimethylanilinium hydroxides (I) to give the ortho- and para-substituted NN-dimethylanilines (II) and (III) has been studied. Radical intermediates are proposed for the intramolecular reaction.
2 citations
1 citations
TL;DR: In this paper, a study was made of base-catalyzed ring closure in the series of some new N-(2-hydroxyethyl)-propargylamines in order to ascertain the effect of a substituent, attached directly to the nitrogen atom, on the direction of cyclization.
Abstract: 1.
A study was made of base-catalyzed ring closure in the series of some new N-(2-hydroxyethyl)-propargylamines in order to ascertain the effect of a substituent, attached directly to the nitrogen atom, on the direction of cyclization.
2.
Methyl-N-(2-hydroxyethyl)- and bis-N-(2-hydroxyethyl)propargylamines, in contrast to other members in the series, which form 2-vinyl-1, 3-oxazolidines in anhydrous media, are cyclized to the corresponding unsaturated morpholines.
3.
The peculiar behavior of bis-N-(2-hydroxyethyl)propargylamine is associated with the possible inhibition of allenic isomerization due to intramolecular reaction between the triple bond and the second hydroxyl group in the transition state.
4.
In order to explain the anomalous cyclization of methyl-N-(2-hydroxyethyl)propargylamine the theory was proposed that conjugation of the free electron pair of the nitrogen atom with the adjacent C-H bonds is possible.
5.
The conversion of N-(2-hydroxyethyl)propargylamines to oxazolidines under the influence of sodium proceeds with a simultaneous, either partial of complete, hydrogenation of the double bond.
6.
The rate of the intramolecular vinylation (cyclization of N-(2-hydroxyethyl)benzylpropargylamine) greatly exceeds the rate of the intermolecular vinylation of the alcohol function by acetylene.