2 edition of The stereochemistry of the decomposition of 1-pyrazolines found in the catalog.
Written in English
|The Physical Object|
|Pagination||v, 36,  l.|
|Number of Pages||36|
Two mechanisms have been proposed to account for the net single inversion of stereochemistry observed in the pyrolysis of 3,5-dialkylpyrazolines. The first, involving initial cleavage of both C-N bonds and formation of a [pi]-cyclopropane intermediate, predicts completely racemic singly inverted product on pyrolysis of an optically active. The - and -isomers of several substituted phosphetanium bromides are rapidly equilibrated on treatment with hydroxide ion and give rise to a predominance of one isomeric phosphetan 1-oxide in each case.
1,3-Dipolar cycloaddition of Earylideneindanones 1a-h and Z-aurones 3a-c with diazomethane provided trans-spiropyrazolines 2a-h and 4a-c, respectively, as sole products. Cyclopropanation refers to any chemical process which generates cyclopropane rings. It is an important process in modern chemistry as many useful compounds bear this motif; for example pyrethroids and a number of quinolone antibiotics (ciprofloxacin, sparfloxacin, etc.).However the high ring strain present in cyclopropanes makes them challenging to produce and generally requires the use of.
Summary This chapter contains sections titled: Introduction Structure and Stereochemistry Decomposition of Peroxides Decomposition of Azo‐compounds . The geometric stereoisomers of 3-carbomethoxymethylbromopyrazoline have been prepared. Both compounds have been found to be highly unstable and are transformed readily into the hydrobromide salt of 3-methylcarbomethoxypyrazole. This transformation requires preferential migration of a carbomethoxy group over a methyl group. A stepwise mechanism is proposed for this .
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Spirocyclopropane formation and rearrangement in the thermal and photochemical decomposition of 1-pyrazolines from 9-diazofluorene and bicyclicolefines. Tetrahedron24 (14), Cited by: sition of the 1-pyrazolines leads to the conclusion that cyclopropanes resulting from the decomposition of cis- at transpyrazolines actually have the structure pictured in XVI and XVII, respectively.
The n.r. analyses also confirmed the above stereochemical assign-ments for the cyclopropane (XI) and (XIII). The results of analysis. Stability and stereochemistry in the decomposition of pentasubstituted 1-pyrazolines controlled by interactions between bulky vicinal substituents.
Yoshihiko Nakano, Masashi Hamaguchi, and ; Cited by: The stereochemistry of the decomposition of 1-pyrazolines. By Wun Ten Tai.
Abstract (Thesis) Thesis - University of Florida.(Bibliography) Bibliography: l. Manuscript (Statement of Responsibility) By Wun-Ten Tai Topics: Pyrazolines (lcsh).
Org. Chem. All Publications/Website. OR SEARCH CITATIONSCited by: 9. The stereochemistry of thermolysis of 4-alkylidenepyrazolines Article in Canadian Journal of Chemistry 56(7) February with 15 Reads How we measure 'reads'.
Pyrazolines. The Stereochemistry of the Thermal Decomposition of 5,5-Diphenylpyrazolines1. Studies on the decomposition of ethyl diazoacetate and its reaction with coal.
Formation of a new tetrameric product and reagent access within the coal. Energy & Fuels3 (3), DOI: /efa Albert Lévai, Tamás Patonay. THERMAL AND PHOTOCHEMICAL DECOMPOSITION OF 3,5-DIVINYLSUBSTITUTED 1-PYRAZOLINES1. ~,- + J-~ We wish to report now data on the photochemical and thermal decomposition of the cis- and trans-3,5-divinylpyrazolines ~ and exovlnyl,3-diazabi- cyclo[o]octa-2,7iene systems allow for the first time decomposition studies which could.
(+)-3R,5R- and (+)-3R,5Sethylmethylpyrazolines (34T and 34C, respectively) have been prepared in optically active form. Their stereochemistries have been determined by correlation with (-)-Rhexanol and (-)-Rbromohexane. Pyrolysis of these pyrazolines in the gas phase at ° allows a complete study of the stereochemistry of the 1-pyrazoline decomposition.
34T yields cis The thermal decomposition of spiropyrazolines 2 obtained by the cycloaddition of exocyclic α,β-unsaturated ketones with diazomethane gives spirocyclopropanes 4 with high selectivity and the new β-methylbenzylidene derivatives 3.
The configuration and conformation of the thermolysis products 3 and 4 were elucidated by different n.m.r. methods. The 1-pyrazolines formed by the photochemical and/or thermal cycloaddition of 9-diazofluorene to norbornadiene and norbornene were isolated and submitted to thermal and photochemical decomposition.
The exo 1-pyrazoline from norbornadiene rearranges thermally to 2-(9-spirofluorenylidene)bicyclooctadiene in high yields. Photolysis of the. Photochemical and Thermal Decomposition of 1-Pyrazolines Article (PDF Available) in Canadian Journal of Chemistry 52(24) February with 27 Reads How we measure 'reads'.
Tetrahedron Letters No. 23, pp -Yergamon Press. Printed in Great Britain. THE STEREOCHEMISTRY OF DECOMPOSITION OF 1-DIAZOPHENYLt-BUTYLCYCLOHEXANES Linda Seghers and Harold Shechter Department of Chemistry, The Ohio State University, Columbus, Ohio (lieceived in USA 1`3 February ; received in UK for publication.
Quantum yields for photochemical nitrogen extrusion from seven 1-pyrazolines were found to range from to but 4-oxo-3,3,5,5-tetramethylpyrazoline (8) proved to be photochemically and thermally remarkably stable.
4-Isopropylidene-3,3,5,5-tetramethylpyrazoline (7) decomposed thermally with E a = kcal mol −1 and ΔS ≠ = e.u. Stereochemistry of the Thermal and Photochemical Decomposition of Bicyclic Vinyl‐1‐pyrazolines. The 1,3‐dipolar cycloaddition of diazomethane, diazoethane, and 3‐diazo‐1‐propene to cyclic olefines results in the formation of the bicyclic 1‐pyrazolines 8, 11 –18, which form upon thermal and photochemical decomposition the hydrocarbons 9, 10, 19 – Determination of the Stereochemical Changes at Carbons-3 and -5 of 1-Pyrazolines on Their Thermal Conversion to Cyclopropanes Article in Canadian Journal of Chemistry 49(1) February.
Thermal decomposition of a series of 4- and 5-alkyl-substituted 3-methylmethoxycarbonyl (or 3-acetyl)-Δ-pyrazolines has been investigated. The relative rates for the decomposition of these compounds were given.
Two mechanisms are proposed, one for the formation of olefin and the other for the formation of cyclop. Spirocyclopropane formation and rearrangement in the thermal and photochemical decomposition of 1-pyrazolines from 9-diazofluorene and bicyclicolefines Author links open overlay panel N.
Filipescu J.R. DeMember 1. Title: Mechanistic studies of the decomposition of 1-pyrazolines: Creator: Szilagyi, Sandor: Date Issued: Description: A series of pyrazolines having a carbomethoxy group on C-3 and a bridge (number of the carbon atoms = 3, 4, 5) connecting C-3 and C-4 was synthesized and studied.
l-Carbomethoxy-2,3-diazabicyclo ()octene-5d₁ was also prepared and the overall deuterium. The thermal decomposition of bicyclic divinyl-cyclopropanes and bicyclic divinyl-Δ 1-pyrazolines leads to indentical products, suggesting a common reaction pathway.
1-pyrazolines leads to indentical products, suggesting a common reaction pathway.The thermal decomposition of spiropyrazolines 2 obtained by the cycloaddition of exocyclic α,β-unsaturated ketones with diazomethane gives spirocyclopropanes 4 with high selectivity and the.(Ph.D.)--University of Illinois at Urbana-Champaign, The goal of this investigation was the determination of the stereochemical course of the decomposition of diazopyrazoline 1a to 3,5-dimethyl-3,4-heptadiene (2).
To achieve this goal, a stereospecific synthesis of 1a which would permit its optical resolution was devised.