Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. Part 9. N-substituted 2,4,6-triphenylpyridiniums, 5,6-dihydro-2,4-diphenylbenzo[h]quinoliniums, and 5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]acridiniums: kinetic rate variation with structure of the N-substituent

Katritzky, Alan R.; Sakizadeh, Kumars; Ou, Yu Xiang; Jovanović, Bratislav Ž.; Musumarra, Giuseppe; Ballistreri, Francesco P.; Crupi, R.

doi:10.1039/p29830001427

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…On the other hand, the substrate with an ethyl group ( 3f ) or a long n -decyl group ( 3e ) gave lower yields (entries 4 and 5, respectively). The reactivity of alkyl bromides toward nucleophiles is known to be reduced as the alkyl chain is lengthened . Similarly, the generated thioesters bearing a long alkyl chain could be more inert to further acyl-substitution reactions.…”

Section: Resultsmentioning

confidence: 80%

Microwave-Assisted Direct Thioesterification of Carboxylic Acids

et al. 2017

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A one-pot synthesis of thioesters directly from carboxylic acids, N,N'-diphenylthiourea, triethylamine, and primary alkyl halides is described. Microwave-assisted heating and a catalytic amount of 4-(dimethylamino)pyridine (DMAP) further improved the yields. Both aromatic and aliphatic carboxylic acids were converted to the corresponding thioesters, and many functional groups were compatible with this reaction. Several possible reaction intermediates were investigated, and the quaternary ammonium salts, derived from alkyl halides and tertiary amines, were the intermediates to yield thioesters. A new reaction mechanism for this thioesterification is proposed.

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Section: Resultsmentioning

confidence: 80%

Microwave-Assisted Direct Thioesterification of Carboxylic Acids

et al. 2017

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“…The data matrix contains elements xjk, where index i is used for the experimental measurements (variables) and index k for the chemical compounds (objects). Each element is described by equation (2), where the number A of significant cross-terms (components), and the parameters b,,, t,k are calculated by minimizing the squared residuals eik, after subtracting 2, (the mean value of the k experimental quantities xt).…”

Section: In Agreement With Previousmentioning

confidence: 99%

Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. Part 19. Chemometric investigation of the simultaneous dependence of S N 2 rates on alkyl group structure and leaving group nucleofugacity

Musumarra¹,

BRUNO²,

Katritzky³

et al. 1985

J. Chem. Soc., Perkin Trans. 2

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The preparation and kinetics of nucleophilic displacement are reported for four pbranched primary alkyl groups attached t o neutral nucleofuges. Principal-component analysis on a set of 10 nucleophilic substitution reactions with neutral and anionic nucleofuges finds that the first principal component accounts for 70% of the variance and confirms that the tri-and penta-cyclic nucleofuges are similar to chloride ion in leaving-group activity. Partial least-squares analysis shows that the nucleophilic displacement rates for the tricyclic derivatives (2) depends on substituent shape (as measured by the Verloop parameter) rather than on size as measured by iES. The G* and polarizability terms are also important.Tabk4. First-( k , ) and second-order (k,) rate constants for the reactions of compounds in series (2) and (3) with piperidine in chlorobenzene at 100 "C

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“…Use of 5,6,8,9-tetrahydro-8-phenyldibenzo[c,h]acridine (3) as a leaving group is known6 to promote N-C bond heterolysis by steric compression and gives rates enhanced over the 2,4,6triphenylpyridine analogues. 6 The xanthylium salt (1) was treated at 25 "C with a variety of secondary alk ylamines in nucleophilic solvents (Scheme 1) and the products analysed by 'H and I3C n.m.r. spectroscopy and gas chromatography-mass spectrometry. '…”

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confidence: 99%

Nucleophilic displacement with heterocycles as leaving groups. Part 16. Reactions of secondary alkyl primary amines with 5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]xanthylium trifluoromethanesulphonate to give intermediates solvolysing without rearrangement

Katritzky¹,

López-Rodrı́guez²,

Keay³

et al. 1985

J. Chem. Soc., Perkin Trans. 2

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Representative secondary alkyl primary amines R1 R'CHNH, react with the title pyrylium cation in acetic acid, alcohols, phenols, and NN-dimethylaniline acting as nucleophilic solvents to give 0and C-(secondary alkyl) products. Absence of carbenium ion rearrangements is consistent with reaction via intimate ion-molecule pairs formed rapidly from the corresponding pyridinium cations.This series of papers has investigated the kinetics and mechanism of the nucleophilic development of N-primary alkyl and N-secondary alkyl groups from pyridinium compounds. As recently summarized,2 cogent evidence has been obtained for discrete mechanisms: classical SN2, classical S,l uia free carbenium ions, and both first-and second-order reactions of intimate ion-molecule pairs. The identification of reaction products, and particularly the presence or absence of rearrangement, has played an important part in the interpretation.N-n-Octyl-and N-n-dodecyl-acridiniwn ions are solvolysed in phenol at 140 "C to give a mixture of the n-alkyl phenyl ethers and all the isomeric secondary straight-chain 0-and palkylphenols, probably uia carbenium ion intermediates. Studies of the solvolysis reactions of 1-(1-methylbuty1)-and 1-( 1 -ethylpropyl)-5,6-dihydro-2,4-diphenylbenzo[h]quinolinium salts have revealed that these reactions proceed via free carbenium ions with rearrangement in trifluoroacetic acid and l,l, 1,3,3,3-hexafluoropropan-2-o1, yet in acetic acid solvolysis occurred without any rearrangement.We recently reported reactions of 2,4,6-triphenylpyrylium salts with the secondary alkyl primary amines l-phenylethylamine and (diphenylmethy1)amine. Spontaneous further reaction of the intermediate pyridinium cations led to the roomtemperature conversion of these amines into ethers, esters, and C-alkylated products.' Chiral 1-phenylethylamine (in acetic acid) gave 1-phenylethyl acetate with complete inversion of configurati~n,~ indicating solvolysis via a tight ion-molecule pair.We now report that aliphatic secondary alkyl primary amines react at ambient temperature with the xanthylium salt (1) to give solvolysis products of cations (2) without rearrangement.

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Cited by 4 publications

References 4 publications

Microwave-Assisted Direct Thioesterification of Carboxylic Acids

Microwave-Assisted Direct Thioesterification of Carboxylic Acids

Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. Part 19. Chemometric investigation of the simultaneous dependence of S N 2 rates on alkyl group structure and leaving group nucleofugacity

Nucleophilic displacement with heterocycles as leaving groups. Part 16. Reactions of secondary alkyl primary amines with 5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]xanthylium trifluoromethanesulphonate to give intermediates solvolysing without rearrangement

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