Aspects of the mechanism of the Wittig reaction between cyclic anhydrides and stabilized phosphoranes

1982 ◽  
Vol 35 (10) ◽  
pp. 2077 ◽  
Author(s):  
AD Abell ◽  
RA Massy-Westropp
Keyword(s):  
Intermediate Product ◽  
Wittig Reaction ◽  
Product Formation ◽  
Initial Reaction ◽  
Kinetic Control ◽  
Cyclic Anhydrides ◽  
Influence Of Substituents ◽  
Phthalic Anhydrides

It has been established that the Wittig reaction between cyclic anhydrides and methoxycarbonylmethylenetriphenylphosphorane, a reaction used for the preparation of enol-lactones, proceeds via an acyclic intermediate acylated phosphorane for the three classes of anhydrides studied: succinic, maleic and phthalic. The formation of the acyclic intermediate can be irreversible or reversible, depending on the structure of the anhydride. The stereochemistry of the enol-lactones produced is not controlled by the initial reaction of the anhydride with the ylide but either during or after cyclization of the acyclic intermediate. Product formation appears to be under kinetic control with all the anhydrides studied. The influence of substituents in substituted phthalic anhydrides has been investigated.

The synthesis, isomerization and stability of some enol-lactones

1982 ◽  
Vol 35 (9) ◽  
pp. 1903 ◽  
Author(s):  
IR Doyle ◽  
RA Massy-Westropp
Keyword(s):  
Thermal Decomposition ◽  
Wittig Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Kinetic Control ◽  
Relative Stabilities ◽  
Diels Alder Reaction ◽  
Wittig Reactions

The photoisomerization of enol-lactones is described. Thermal decomposition of (E) and (Z) ethyl 3-oxo-1,3,3aβ,4α,7α,7aβ-hexahydro-4,7-methanoisobenzofran-1-yideneacetates provides a good route to (E) and (Z) ethyl 5-oxo-2,5-dihydrofuran-2-ylideneacetates. Other examples of this retro-Diels-Alder reaction are reported. The relative stabilities of (E) and (Z) enol-lactones from the Wittig reaction between substituted succinic anhydrides and ethoxycarbonylmethylenetriphenylphosphorane have been determined. These Wittig reactions are under kinetic control.

Mechanism of Wittig reaction with cyclic anhydrides

1992 ◽  
Vol 70 (7) ◽  
pp. 1985-1996 ◽  
Author(s):  
Margaret M. Kayser ◽  
Krista L. Hatt ◽  
Donald L. Hooper
Keyword(s):  
Wittig Reaction ◽  
Reaction Pathway ◽  
Spectroscopic Methods ◽  
Cyclic Anhydrides

The reactions of stabilized phosphoranes with cyclic anhydrides give enol-lactones as final products. The initial condensation, however, leads to the formation of acyclic adducts that are observable by NMR, can be easily trapped, and, in some cases, can be isolated. A study of the mechanism of these condensations by NMR spectroscopic methods and by various trapping experiments is described and the reaction pathway is proposed.

Notizen: High Pressure Reactions, I Evidence for Two Concurrent Mechanisms in Lewis-Acid Catalyzed Alkylation of Aromatics with Olefins

1976 ◽  
Vol 31 (2) ◽  
pp. 277-278 ◽  
Author(s):  
H. Tiltscher ◽  
R. Lohmüller
Keyword(s):  
High Pressure ◽  
Pressure Range ◽  
Reaction Rate ◽  
Initial Reaction Rate ◽  
Product Formation ◽  
Initial Reaction ◽  
Homogeneous Reaction ◽  
Reaction Conditions ◽  
Alkylation Of Benzene ◽  
Acid Catalyzed

A kinetic study was made of the primary step of the alkylation of benzene with propylene and ferric chloride as catalyst under homogeneous reaction conditions at several pressures up to 2 kbar. Initial reaction rate of cumene formation shows a minimum in the medium pressure range, thus indicating that product formation occurs via two different reaction paths with opposite pressure dependence.

Evidence against reversible Wittig reaction of a stabilized ylide: high (E)-olefin selectivity under kinetic control

1987 ◽  
Vol 52 (20) ◽  
pp. 4637-4639 ◽  
Author(s):  
E. Vedejs ◽  
T. Fleck ◽  
S. Hara
Keyword(s):  
Wittig Reaction ◽  
Kinetic Control ◽  
Olefin Selectivity

scholarly journals Product Formation by the Promiscuous Lanthipeptide Synthetase ProcM is under Kinetic Control

2015 ◽  
Vol 137 (15) ◽  
pp. 5140-5148 ◽  
Author(s):  
Yi Yu ◽  
Subha Mukherjee ◽  
Wilfred A. van der Donk
Keyword(s):  
Product Formation ◽  
Kinetic Control

Comparative Study of the Sol-Gel and Metallo-Organic Decomposition (MOD) Processes for the Preparation of Inorganic Materials

1992 ◽  
Vol 271 ◽  
Author(s):  
Gustavo R. Paz-Pujalt ◽  
W. Nie ◽  
C. Lurin
Keyword(s):  
Comparative Study ◽  
Chemical Reactivity ◽  
Sol Gel ◽  
Product Formation ◽  
Inorganic Materials ◽  
Kinetic Control ◽  
Reaction Thermodynamics ◽  
Points Of View ◽  
Gel Processing ◽  
Organic Decomposition

ABSTRACTSol-Gel processing and Metallo-Organic Decomposition are contrasted from the thermodynamics and chemical reactivity points of view. Differences and similarities on precursor requirements, processing characteristics, processing intermediates, and product formation pathways are outlined. Some specific examples are presented and their reaction thermodynamics are compared. Some conclusions regarding thermo-dynamic versus kinetic control are drawn from these examples.

A Mechanistic Study of the Wittig Reaction Between a Cyclic Anhydride and a Stabilized Phosphorane

1988 ◽  
Vol 41 (8) ◽  
pp. 1243 ◽  
Author(s):  
AD Abell ◽  
BM Clark ◽  
WT Robinson
Keyword(s):  
Structure Analysis ◽  
Succinic Anhydride ◽  
Wittig Reaction ◽  
Phosphonium Salt ◽  
Mechanistic Study ◽  
Cyclic Anhydride ◽  
X Ray ◽  
Cyclic Anhydrides

The structure of an isolated acyclic intermediate in the Wittig reaction between succinic anhydride and ethoxycarbonylmethylenetriphenylphosphorane has been shown by X-ray structure analysis and DEPT n.m.r .to be the phosphorane (4a) rather than the alternative phosphonium salt (4b). However, an intermediate was not observed in the Wittig reaction between the phosphorane (1b) and cyclic anhydrides. Both the stabilized phosphoranes (1a,b) react with succinic, phthalic and glutaric anhydrides stereoselectively to produce E enol lactones. Some mechanistic aspects are discussed. The assignment of the enol lactone stereochemistry was achieved by n.O.e. difference n.m.r. methods.

Theoretical study of regioselectivity in nucleophilic addition to unsymmetrical cyclic anhydrides. Intrinsic reactivity and influence of the cation

1981 ◽  
Vol 59 (16) ◽  
pp. 2457-2462 ◽  
Author(s):  
Margaret M. Kayser ◽  
Odile Eisenstein
Keyword(s):  
Carbonyl Group ◽  
Nucleophilic Addition ◽  
Nucleophilic Attack ◽  
Dominant Factor ◽  
Molecular Orbital Calculations ◽  
Optimum Position ◽  
Cyclic Anhydrides ◽  
Intrinsic Reactivity ◽  
Reaction Media ◽  
Phthalic Anhydrides

Ab initio molecular orbital calculations have been carried out for the series of succinic, maleic, and phthalic anhydrides unsymmetrically substituted with CH3, CH3O, Cl, F, and CN. The size of the LUMO coefficient on the carbon atom of the carbonyl group provides a reliable guide to the relative reactivities of the two carbonyl functions. The predictions based on the intrinsic reactivities are in good agreement with the regioselectivities observed in metal hydride reductions of succinic anhydrides. In the series of maleic and phthalic anhydrides the above considerations are applicable only to methyl derivatives. The compounds substituted with lone pairs-bearing groups (OCH3, Cl, F) form stable chelates with the cations present in the reaction media. Since the chelated carbonyl group is strongly activated toward the nucleophilic addition, the "bridging" effect is the dominant factor controlling orientation of hydride addition. The optimum position for the nucleophilic attack in cyclic anhydrides was calculated. The results confirm the generality of the nonperpendicular, restricted path of nucleophilic attack on the carbonyl group in succinic anhydride.

ChemInform Abstract: A Highly Stereoselective Synthesis of (E)-Enol Lactones by the Wittig Reaction of Cyclic Anhydrides with (α-Alkoxycarbonylethylidene)triphenylphosphorane.

ChemInform ◽  
1987 ◽  
Vol 18 (29) ◽  
Author(s):  
S. TSUBOI ◽  
H. FUKUMOTO ◽  
H. WADA ◽  
A. TAKEDA ◽  
K. FUKUYAMA
Keyword(s):  
Wittig Reaction ◽  
Stereoselective Synthesis ◽  
Cyclic Anhydrides
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