Allyl pyrolysis

Oxazol-4(5ff)-one, 5-acetyl-5-methyl-synthesis, 6, 225 Oxazol-4(5ff)-one, 2-phenyl-photorearrangement, 6, 200 synthesis, 6, 225 Oxazol-5(2ff)-one, 2-acyl-2,4-disubstituted pyrolysis, 6, 200 Oxazol-5(2H)-one, allyl-photochemical rearrangement, 6, 200 Oxazol-5(2ff)-one, 2-arylmethylene-synthesis, 6, 227... 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Pentadiene has been prepared by the interaction of allyl bromide and vinyl bromide in the presence of magnesium and by the pyrolysis of 1,5-pentanediol diacetate or 4-penten-l-ol acetate. The present procedure is essentially that of Shoemaker and Boord with some modifications. ... 

Sulfenyl chlondes react with allyl alcohols to yield allyl sulfenates, whtch are in equihbnum with the allyl sulfoxides [12] (equation 9a) These products can be oxidized to the corresponding sulfones (equation 9b) Pyrolysis of the sulfoxides gives sulfines or evidence for the presence of sulfmes Pyrolysis of sulfones leads to unsamrated compounds by extrusion of sulfur dioxide [12] (equation 9c)... 

The pyrolysis of sodium chlorodinuoroacetate is still a widely used, classical method for generating difluorocarbene, especially with enol and allyl acetates [48, 49, 50, 51] (equation 21) A convenient alternative that avoids the hygroscopic salt uses methyl chlorodifluoroacetate with 2 equivalents of a lithium chlonde-hexa-methylphosphoric triamide complex at 75-80 °C in triglyme [52], Yields are excellent with electron-rich olefins but are less satisfactory with moderately nucleophilic alkenes (4-5% yields for 2-bulenes)... 

In a related reaction, pyrolysis of allylic ethers that contain at least one a hydrogen gives alkenes and aldehydes or ketones. The mechanism is also pericyclic"" ... 

Matrix IR spectra of various silenes are important analytical features and allow detection of these intermediates in very complex reaction mixtures. Thus, the vibrational frequencies of Me2Si=CH2 were used in the study of the pyrolysis mechanism of allyltrimethylsilane [120] (Mal tsev et al., 1983). It was found that two pathways occur simultaneously for this reaction (Scheme 6). On the one hand, thermal destruction of the silane [120] results in formation of propylene and silene [117] (retroene reaction) on the other hand, homolytic cleavage of the Si—C bond leads to the generation of free allyl and trimethylsilyl radicals. While both the silene [117] and allyl radical [115] were stabilized and detected in the argon matrix, the radical SiMc3 was unstable under the pyrolysis conditions and decomposed to form low-molecular products. 

Among phosphonate esters (170) used in olefin synthesis were those with R = S-CeHi-Br-/ , S02 C6H4-Br-A CO-NHR, and S CHa CEi-XHa. The allyl vinyl thio-ethers (171) obtained using the last of these gave a-allyl-aldehydes on pyrolysis in the presence of red mercuric oxide. 

More recently, a number of reports dealing with 1,3-sulfonyl shifts which proceed by other mechanisms have been published. For example, Baechler and coworkers suggested that the higher activation enthalpy observed for the isomerization of the deuterium labeled methallyl sulfone 72 in nitrobenzene at 150°C as compared to the corresponding sulfide, together with the positive entropy of activation may be taken as evidence for a homolytic dissociation mechanism (equation 44). A similar mechanism has also been suggested by Little and coworkers for the gas-phase thermal rearrangement of deuterium labelled allyl sec-butyl sulfone, which precedes its pyrolysis to alkene and sulfur dioxide. 

Deyerl and co-workers have also studied the photodissociation of the jet-cooled allyl radical produced in a flash pyrolysis source.148,149 The allyl radical is excited near 250 nm and H-atom product is detected by... 

The nonacarbonyldiiron-induced transformation of oxazabicyclo[2.2.2] octenes (12) into condensed azetidinones is intriguing mechanistically but will obviously have limited synthetic application (Scheme 15).37 The /(-lactam (14a), among other products, is isolated directly from the iron carbonyl reaction but the dimethyl analog (14b) is obtained by pyrolysis of an isolable intermediate <7-7r-allyl complex (13b). 

A. J. Colussi, F. Zabel, and S. W. Benson, Very low-pressure pyrolysis of phenyl ediyl ether, phenyl allyl ether, and benzyl methyl-edier and endialpy of formation of phenoxy radical,/ t. J. Chem. 

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