Generation and reactivity of the 1-nitrocyclopropyl anion

O'bannon, P. E.; Dailey, William P.

doi:10.1021/ja00208a026

Cited by 25 publications

(10 citation statements)

References 1 publication

(1 reference statement)

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“…preted by a mechanism that involves attack on CS 2 or SO 2 by oxygen, extruding CS 2 O or SO 3 -[Equations (3) and (4)]. The resonance stabilization that exists for the acyclic nitroalkane anions is less important in the strained nitrocyclopropane anion, resulting in less product formation from oxygen attack for the cyclic anion.…”

Section: Methodsmentioning

confidence: 99%

“…2 Geometry optimization at a higher level of theory, however, later indicated that the triplet state of the nitrocyclopropyl anion lies considerably higher in energy than the ground state. 3 With the ground state multiplicity problem resolved theoretically, the gas-phase acidity of a-substituted cyclic and acyclic alkanes continues to be a subject of extensive study. [4][5][6] In general, acidity is the result of trade-off between inductive, resonance, polarizability and lone-pair electron repulsion effects and is a measure of stabilization for the deprotonated carbanions.…”

Section: Introductionmentioning

confidence: 99%

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Gas-Phase Ion–Molecule Reactions of Small Nitroalkanes and Their Deprotonated Anions

Kato

Carrigan

DePuy

et al. 2004

Eur J Mass Spectrom (Chichester)

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Gas-phase reactions of nitromethane (1), nitroethane (2), 2-nitropropane (3), 2-methyl-2-nitropropane (4) and nitrocyclopropane (5) were studied at 300 K using the flowing afterglow technique. These nitroalkanes react with gas-phase bases HO(-), CH(3)O(-) and HOO(-) very rapidly with rate coefficients of (2.5-4.3) x 10(-9) cm(3) s(-1) and reaction efficiencies of 60-100%, for example, k = 3.2 x 10(-9) cm(3) s(-1) (86%) for 5 reacting with hydroperoxide anion. Proton transfer (PT) is the only reaction observed for 1 while elimination (E2) is the exclusive pathway for 4 yielding isobutene and NO(2)(-). Both PT and E2 reactions are observed for 2, 3 and 5, the former being the major pathway. Deprotonated anions of 1, 2, 3 and 5 were subjected to reactivity studies with CH(3)I, CO(2), CS(2) and SO(2). Nucleophilic substitution (S(N)2) reaction occurs with CH(3)I while characteristic products CS(2)O(-) and SO(3)(-) are formed from CS(2) and SO(2), respectively, along with competing adduct formation. The SN(2) rate is greater, whereas the reactivities with the triatomic reagents are smaller for deprotonated nitrocyclopropane than for the other acyclic anions. These observations strongly suggest that the reactions of nitroalkane [M - H](-) anions occur through initial attack from the terminal oxygen; the nitrocyclopropane carbanion is more strained and, thus, less stabilized by resonance [R(2)C(-) - NO2 <--> R(2)=NO(2)(-)] resulting in the greater basicity/nucleophilicy and the less negative charge on the oxygen site.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gas-Phase Ion–Molecule Reactions of Small Nitroalkanes and Their Deprotonated Anions

Kato

Carrigan

DePuy

et al. 2004

Eur J Mass Spectrom (Chichester)

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“…Statt Die Reaktionen der durch Racematspaltung hergestellten Glycinderivate verlaufen so gut, daD man diese Synthesebausteine vorzieht, auch wenn sich eine gewiinschte a-verzweigte Aminosaure von einer naturlichen Amiiiosaure ableitet, also eine der Seitenketten ,,proteinogen" ist, und damit die Herstellung nach dem SRS-Prinzip moglich ware. [48,89] und Nitronaten [273,274] Wohl wissend um die Komplexitat der Reaktionen von Li-Verbindungencs3 2 1 -2 9 1 formulieren wir in Schema 28 rnit aller gebotenen Vorsicht ein mechanistisches M~d e l l [~~~~.…”

Section: Umpolung Verdoppelt Die Moglichkeitenunclassified

Die Selbstregeneration von Stereozentren (SRS) — Anwendungen, Grenzen und Preisgabe eines Syntheseprinzips

1996

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“…It was shown that the adducts of t-BuOLi to aromatic aldehydes could also be used as bases and in-situ sources of the aldehydes for reactions of unstable enolates [50]. The effect was recently also observed in additions [51] of the unstable [52] nitronate from nitrocyclopropane to benzaldehyde. closporin-A analogues2') [2].…”

Section: 2mentioning

confidence: 99%

C‐Alkylation of Peptides through Polylithiated and LiCl‐Solvated Derivatives Containing Sarcosine Li‐Enolate Units

Seebàch¹,

Bossler

Gründler

et al. 1991

Helvetica Chimica Acta

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The tripeptide and hexapeptide derivatives Boc-Gly-Sar-MeLeu-OH (5b), Boc-Ala-Sar-Sar-OH (6b), BocAla-Sar-MeLeu-OH (7b), and Boc-Abu-Sar-MeLeu-Val-MeLeu-Ala-OH (12b) can be poly-deprotonated (tri-and pentalithio derivatives K and P, respectively), and thus C-alkylated on sarcosine (Sar) moieties with Me1 and ally1 or PhCH2Br. The polylithiated species are solubilized in THF, and their reactivity modified by excess base (lithium diisopropylamide (LDA)), by added LEI, and/or the cosolvent N,N'-dimethylpropyleneurea (DMPU). Optimization of the reaction conditions for methylation in the cases of 7b (Table 3) and 12b (Scheme 8 ) gave products in which the Sar residue of the educt has been transformed into a Me-D-Ala unit in yields of 80 (9c/8c) and 67% (14c/13c), respectively, and with a diastereoselectivity of ca. 4 : 1. Less selective methylations and benzylations were observed with the tripeptides 5b and 6b containing only one stereogenic center; also, excess base and alkyl halide may lead to double alkylations in those latter two cases (Tables 1 and 2 ) . No epimerization of stereogenic centers was detected under the strong-base conditions. The analysis of the products was accomplished by a combination of NMR and FAB-MS spectroscopy, as well as by hydrolysis to the parent amino acids, subsequent formation of derivatives with isopropyl isocyanate, and GC analysis on the chiral column Chirasil-Val". For instance b-amino acids, amino thioacids, (+endothiopeptides), ethylenediamines (-+reduced peptides), 5-amino-4-0x0-amino acids (+oxomethylene peptides), ct -hydroxy acids (+depsipeptides), phospho-amino or -hydroxy acids (+phosphopeptides, phosphono-depsipeptides). Other modifications are called thiomethylene-, hydroxymethylene-, carboretro-or inverso-, and alkene-peptides. For a review about such modifications, see [6]. A) 3, 4,

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Generation and reactivity of the 1-nitrocyclopropyl anion

Cited by 25 publications

References 1 publication

Gas-Phase Ion–Molecule Reactions of Small Nitroalkanes and Their Deprotonated Anions

Gas-Phase Ion–Molecule Reactions of Small Nitroalkanes and Their Deprotonated Anions

Die Selbstregeneration von Stereozentren (SRS) — Anwendungen, Grenzen und Preisgabe eines Syntheseprinzips

C‐Alkylation of Peptides through Polylithiated and LiCl‐Solvated Derivatives Containing Sarcosine Li‐Enolate Units

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