Vinylic cations from solvolysis. XX. Ion pairs and free ions in the solvolysis and isomerization of 1,2-dianisyl-2-phenylvinyl halides and mesylates. Use of cis-trans isomerization as a mechanistic tool

Rappoport, Zvi; Apeloig, Yitzhak

doi:10.1021/ja00837a023

Cited by 17 publications

(2 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…D-7400 Tübingen 0932 -0776/88/0700 -0807/$ 01.00/0 reactivities. Rappoport and Apeloig reported for instance [6] relative reactivities of some nucleophiles toward the l,2-di-p-methoxyphenyl-2-phenylvinyl cation at 120 °C in acetic acid solution. The following relative reactivities (relative to CH 3 COO~) were given: Br (45.5), CP (15.2), CH 3 COO~ (1.0), CH 3 0-S0 3 " (0.16) and CH 3 COOH (0.0024).…”

Section: Introductionmentioning

confidence: 99%

Reactions of Substituted Vinyl Cations in Acetonitrile Solution as Studied by Flash Photolysis

Kobayashi

Zhu

Schnabel

1988

Zeitschrift Für Naturforschung B

View full text Add to dashboard Cite

Vinyl cations I+, I+b, I+c of the structure R′2C=CR″ (I+a: R′ = R″ = anisyl; I+b R′ = phenyl.R″ = anisyl. I+c: R′ - methyl.R″ = anisyl) were generated by flash photolysis of corresponding bromides. Lifetime measurements yielded the following: substitution of aromatic groups in 2-position by methyl groups largely improved the electrophilicity of the vinyl cations. The nucleophilicity of typical compounds (ketone, ester, alcohol, olefin) was measured.

show abstract

Section: Introductionmentioning

confidence: 99%

Reactions of Substituted Vinyl Cations in Acetonitrile Solution as Studied by Flash Photolysis

Kobayashi

Zhu

Schnabel

1988

Zeitschrift Für Naturforschung B

View full text Add to dashboard Cite

show abstract

“…Values of k H o/k D 0 for ratedetermining protonation of substituted alkenes are high [23], and'recentiy collected kRCOOH/kRCOOD values show that the same is also true in AcOH [5]. Examples are the hydrolysis of o-acetoxy-p-rnethoxystyrene [5] which is a close model for our esters, the addition of AcOH to p-methoxystyrene [5], and the cis-trans isomerization of 1,2-dianisyl-2-phenylethylenes [24] where the kAcOH/kAcOD values are 3.4,3.45 and 2.55, respectively. On the other hand, the kAcOH/kAcOD values for acetolysis of vinylic substrates via SN I are consistently 1.0 ± 0.2 [5], and from these values and those for the AdE-E route it was estimated that the acetolyses of a-bromoand o-chloro-p-methoxystyrenes (where kAcOH/kAcOD values are 1.45 and 1.94 respectively) are> 90% SN I for the bromide and a combination of a dominant SN I and an appreciable AdE-E routes for the chloride [5].…”

Section: The Hydrolysis Mechanism In Acohmentioning

confidence: 98%

Solvolysis of 1‐p‐Methoxyphenyl‐2‐Methylpropen‐1‐Yl Trifluoroacetate and 3,5‐Dinitrobenzoate

Rappoport

Kaspi

1974

Israel Journal of Chemistry

Self Cite

View full text Add to dashboard Cite

The reactions of l-p-methoxyphenyl-2-methylpropen-I-yl trifluoroacetate (I-OCOCF,) and 3,5-<1initrobenzoate (I-OONB) in AcOH/NaOAc or with amines in 2,2,2-trifluoroethanol (TFE) were investigated. In TFE, I-OONB gives trifluoroethyl 3,5-<1initrobenzoate (II) and the ketone AnCOCHMe, (III) in a second order reaction with five amines and with CF, CH, ONa, and I-OCOCF, gives a second order reaction with 2,6-lutidine. In AcOH/NaOAc, I-OCOCF, gives the corresponding acetate I-OAc, and I-OONB gives I-OAc and III. The kAcOH/k AcOO values are 5.5 -6.2 for I -OCOCF, and 1.03 ± 0.05 for I-OONB. It is suggested that the rate determining step in TFE is the attack of CF ,CH,O-(formed from the amine and TFE) on the carbonyl of the ester group in a BAC2 mechanism. In AcOH, an electrophilic addition-elimination mechanism (AdE-E) for the reaction of I -OCOCF, is supported by the solvent isotope effect. The solvent isotope effect and the products from I-OONB in AcOH are consistent with an SN 1 mechanism, but since the kCl/kOONB ratio is lower than that in saturated systems, an AAC2 mechanism cannot be unequivocally excluded. The effect of the leaving group in the vinylic SN I reaction is discussed.Many mechanistic routes are available for nucleophilic vinylic substitution [I), and we previously showed that the vinylic SN1 mechanism [2] operates for many a-arylvinyl substrates [3]. Gal had shown [4][5][6] that competition of this route with electrophilic addition-elimination (Ad E -E) [7] and with nucleophilic additionelimination (Ad N -E) [I] is important for several systems, and competition with the E2 mechanism was also observed [8].With a-activated substituted vinyl sulphonate esters such as trifluoromethanesulphonates (triflates) [9]

show abstract

ChemInform Abstract: VINYLIC CATIONS FROM SOLVOLYSIS PART 20, ION PAIRS AND FREE IONS IN THE SOLVOLYSIS AND ISOMERIZATION OF 1,2‐DIANISYL‐2‐PHENYLVINYL HALIDES AND MESYLATES, USE OF CIS‐TRANS ISOMERIZATION AS A MECHANISTIC TOOL

Rappoport¹,

Apeloig²

1975

Chemischer Informationsdienst

View full text Add to dashboard Cite

Vinylic cations from solvolysis. XX. Ion pairs and free ions in the solvolysis and isomerization of 1,2-dianisyl-2-phenylvinyl halides and mesylates. Use of cis-trans isomerization as a mechanistic tool

Cited by 17 publications

References 12 publications

Reactions of Substituted Vinyl Cations in Acetonitrile Solution as Studied by Flash Photolysis

Reactions of Substituted Vinyl Cations in Acetonitrile Solution as Studied by Flash Photolysis

Solvolysis of 1‐p‐Methoxyphenyl‐2‐Methylpropen‐1‐Yl Trifluoroacetate and 3,5‐Dinitrobenzoate

ChemInform Abstract: VINYLIC CATIONS FROM SOLVOLYSIS PART 20, ION PAIRS AND FREE IONS IN THE SOLVOLYSIS AND ISOMERIZATION OF 1,2‐DIANISYL‐2‐PHENYLVINYL HALIDES AND MESYLATES, USE OF CIS‐TRANS ISOMERIZATION AS A MECHANISTIC TOOL

Contact Info

Product

Resources

About