Pyrolysis allyl ethers

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"" ... 

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. 

Fragmentation of 1,3-diols 7-34 Decarbonylation of p-hydroxy carboxylic acids and of p-lactones 7-36 Elimination of CO and C02 from bridged bicydic compounds 7-43 Pyrolysis of P-hydroxy olefins 7-44 Pyrolysis of allylic ethers... 

Pyrolysis of oxime 0-allyl ether (16) resulted in pyridine ring formation, (17), in reasonable yield, along with minor isomer (18) (Scheme 7) <93CPB(41)1297). 

Without additional reagents Oxo compounds by pyrolysis of allyl ethers... 

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. 

In another study several simple silenes RR Si=CH2 (R, R = Me, Vinyl etc.) were formed by laser-powered pyrolysis and were found to form linear polymers, in contrast to the usual behavior of silenes which yield cyclodimers when formed by conventional thermolysis techniques16. Reactions of the silenes in the presence of several monomers such as vinyl acetate, allyl methyl ether and methyl acrylate were also studied. Laser-induced decomposition of silacyclobutane and 1,3-disilacyclobutane gave rise to silenes and other oxygen-sensitive deposits17,18. 

Pentadiene has been prepared by the interaction of allyl bromide and vinyl bromide in the presence of magnesium,8 by the pyrolysis of 1,5-pentanediol diacetate 5-6 or 4-penten-l-ol acetate,6-9 and by the reaction of < -allyl-/3-bromoethyl ethyl ether with zinc.10-11 The present procedure is based on the work of Schniepp and Geller6 and of Paul and Tchelitcheff. 6... 

The results are shown in Table 23. Relative rate data were obtained by simultaneous pyrolysis of pairs of ethers. Since the total rate spread of all ethers from the slowest (ethyl allyl) to the fastest (diphenylmethyl-1-methyl allyl) was only a factor of 40, it is apparent that substituent effects are relatively very small (see ester and vinyl ether eliminations). Polarization in the transition states must, therefore, be minimal. Cookson and Wallis ° noted the following rate trends ... 

The pyrolysis of allyl vinyl ethers derived by acid- or mercuric ion-catalyzed ether exchange of ethyl vinyl ether or substituted vinyl ethers with allylic alcohols produces the corresponding y, 8-unsaturated aldehydes or ketones, respectively. 

Pyrolysis of allyl pentafluorophenyl ether (109) at 480 °C gives mainly the pentafluorotetrahydroindenone (112), the structure of which is confirmed by the conversions shown in Scheme 26. Careful studies of the similar pyrolysis of the deuteriated compound C6Fs 0-CH2 CD CD2 have established that the first product of the semi-Claisen rearrangement (110) probably forms two cyclic intramolecular Diels-Ald adducts, and that the adduct (108) is responsible for mrtho-ortho rearrangement in this S3 tem whereas cleavage of the alternative adduct (111) leads to the final product (112). Isolation of some of these intermediates may be achieved soon. 

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