Kinetics and Mechanism of Addition of Benzylamines to Benzylidene-1,3-indandiones in Acetonitrile

Oh, Hyuck Keun; Yang, Jin Hee; Lee, Hai Whang; Lee, Ikchoon

doi:10.1021/jo000512w

Cited by 30 publications

(7 citation statements)

References 16 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The k H / k D values determined in the present work are summarized in Table . The trend of change in k H / k D with variation of X in the nucleophile, δσ X < 0 → δ( k H / k D ) < 0, is in agreement with those found for other dicarbonyl series. 2c,3a,c, …”

Section: Resultssupporting

confidence: 89%

“…Reference to Table reveals that the rates of three acyclic dicarbonyl compounds 2c,3a are substantially slower than those of the cyclic dicarbonyl activated olefins. 3c, This has been attributed to a built-in planar structure, 5 , in the cyclic dicarbonyls, which will strongly enhance delocalization of anionic charge on the carbanionic center,2c 1 , into the two carbonyl groups in the TS. For the acyclic dicarbonyls reorganization is required to form such a planar structure in the TS, which should result in a higher activation barrier 2c.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics and Mechanism of the Addition of Benzylamines to Benzylidene-3,5-heptadione in Acetonitrile

Oh¹,

Lee²,

Sung³

et al. 2005

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

The addition reaction of benzylamine (XC6H4CH2NH2) to benzylidene-3,5-heptadione (BHD; YC6H(4-)CH=C(COEt)(2)) in acetonitrile is investigated. The rate is slower than the corresponding rate for benzylidenediethylmalonate (YC6H4CH=C(OOEt)(2)) as the result of a greater steric hindrance in the planar dicarbonyl transition state. The kinetic isotope effects (k(H)/k(D)) involving deuterated amine nucleophiles (XC6H4CH2ND2) are greater than 1 (1.37-2.04), indicating N-H bond stretching with concurrent N-C(alpha) and H-C(beta) bond formation in the TS. The trend of change in k(H)/k(D) with variation of substituent X in the nucleophile conforms to the Bell-Evans-Polanyi principle. It has been stressed that the dicarbonyl group activated olefins exhibit insignificant charge imbalance in the TS for the benzylamine additions in acetonitrile as a result of the two strong n(c) --> pi*(C=O) vicinal charge-transfer interactions.

show abstract

Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of the Addition of Benzylamines to Benzylidene-3,5-heptadione in Acetonitrile

Oh¹,

Lee²,

Sung³

et al. 2005

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…A more quantitative analysis of these data appears problematic, because Bernasconi et al 16,28 and Lee et al 29 have previously suggested that the transition states of the amine additions may also be stabilized by O-H interactions as depicted in Scheme 4. Because the additions of carbanions to 1a-d, which are described in Table 3, cannot profit from such O-H interactions, the good agreement between calculated and experimental rate constants in Table 4 argues against a large contribution of these interactions.…”

Section: Correlation Analysismentioning

confidence: 99%

Electrophilicity parameters for 2-benzylidene-indan-1,3-diones—a systematic extension of the benzhydrylium based electrophilicity scale

et al. 2007

View full text Add to dashboard Cite

Kinetics of the reactions of four 2-benzylidene-indan-1,3-diones (1a-d) with carbanions (2a-I) have been studied photometrically in dimethyl sulfoxide solution at 20 degrees C, and the electrophilicity parameters E were determined by the linear free energy relationship log k(2)(20 degrees C) = s(N + E) (eqn (1)). The rate-determining step of these reactions is the nucleophilic attack of the carbon nucleophile at the double bond of the Michael acceptor. Comparisons with literature data show that the linear free energy relationship (eqn (1)) allows the semiquantitative prediction of the reactivities of 2-benzylidene-indan-1,3-diones towards various nucleophiles.

show abstract

“…[19] The considerably higher CH acidity of Meldrums acid relative to those of acyclic esters, such as dimethyl malonate, has been ascribed to the fixed E conformation of the ester linkage in the bislactone structure of Meldrums acid. [20] Abstract: The second-order rate constants of the reactions of nine substituted diethyl benzylidenemalonates 1 a-i with the carbanions 2 a-e have been determined spectrophotometrically in dimethyl sulfoxide (DMSO).…”

Section: Introductionmentioning

confidence: 99%

Determination of the Electrophilicity Parameters of Diethyl Benzylidenemalonates in Dimethyl Sulfoxide: Reference Electrophiles for Characterizing Strong Nucleophiles

Kaumanns

Lucius

Mayr

2008

Chemistry A European J

View full text Add to dashboard Cite

The second-order rate constants of the reactions of nine substituted diethyl benzylidenemalonates 1 a-i with the carbanions 2 a-e have been determined spectrophotometrically in dimethyl sulfoxide (DMSO). Product studies show that the nucleophiles attack regioselectively at the electrophilic C==C double bond of the Michael acceptors to form the carbanionic adducts 4. The correlation log k(20 degrees C)=s(N+E) allows the determination of the electrophilicity parameters E for the electrophiles 1 a-i from the rate constants determined in this work and the previously published N and s parameters for the nucleophiles 2 a-e. The electrophilicities E for compounds 1 a-i cover a range of six units (-17.7>E>-23.8) and correlate excellently with Hammett's substituent constants sigma(p). The title compounds are roughly ten orders of magnitude less reactive than analogously substituted benzylidene Meldrum's acids, their cyclic analogues. Due to their low reactivities, compounds 1 a-i are suitable reference electrophiles for determining the reactivities of highly reactive nucleophiles, such as carbanions with 16

show abstract

Kinetics and Mechanism of Addition of Benzylamines to Benzylidene-1,3-indandiones in Acetonitrile

Cited by 30 publications

References 16 publications

Kinetics and Mechanism of the Addition of Benzylamines to Benzylidene-3,5-heptadione in Acetonitrile

Kinetics and Mechanism of the Addition of Benzylamines to Benzylidene-3,5-heptadione in Acetonitrile

Electrophilicity parameters for 2-benzylidene-indan-1,3-diones—a systematic extension of the benzhydrylium based electrophilicity scale

Determination of the Electrophilicity Parameters of Diethyl Benzylidenemalonates in Dimethyl Sulfoxide: Reference Electrophiles for Characterizing Strong Nucleophiles

Contact Info

Product

Resources

About