Thermal Rearrangement of Cyclopropyl Ketones to Homoallylic Ketones. Relationship to the “Abnormal Claisen Rearrangement”

1965 ◽  
Vol 87 (10) ◽  
pp. 2281-2282 ◽  
Author(s):  
Royston M. Roberts ◽  
Robert G. Landolt
Keyword(s):  
Claisen Rearrangement ◽  
Thermal Rearrangement ◽  
Cyclopropyl Ketones

HALOGEN MIGRATION AND ELIMINATION IN THE CLAISEN REARRANGEMENT OF ALLYL 2,6-DIHALOPHENYL ETHERS

1963 ◽  
Vol 41 (12) ◽  
pp. 2917-2930 ◽  
Author(s):  
E. Piers ◽  
R. K. Brown
Keyword(s):  
Dielectric Constant ◽  
Lewis Acids ◽  
Claisen Rearrangement ◽  
Stannous Chloride ◽  
Ionic Species ◽  
Thermal Rearrangement ◽  
Polar Solvents ◽  
Factors Affecting ◽  
Competitive Reduction ◽  
Catalytic Effects

A study has been made of some factors affecting the migration or elimination of halogen in the Claisen rearrangement of allyl 2,6-dihalophenyl ethers.In the thermal rearrangement of allyl 2,6-dichlorophenyl ether, carried out in a number of solvents of different dielectric constant, halogen migration proceeds somewhat better in highly polar solvents. However, a competitive reduction to the monohalogenated allylphenol occurs in the presence of oxidizable solvents and/or products. The reaction is also complicated by the catalytic effects of certain solvents and the phenolic products, which give results similar to those obtained with Lewis acids. Stannous chloride acts as a Lewis acid and catalyzes the rearrangement of allyl 2,6-dichlorophenyl ether with simultaneous halogen rearrangement. As well, a competitive reductive removal of the halogen takes place. Results from the rearrangement of allyl 2,6-dibromophenyl ether with zinc chloride and of allyl 2,6-dichlorophenyl ether with zinc bromide, as well as those from the stannous chloride reactions indicate that the halogen migration takes place not only by an allylic shift but also via a competitive halogen substitution probably occurring by an Sn2′ pathway possibly assisted by a zinc halide bridge mechanism and/or an ionic species such as [Formula: see text].

Thermal Rearrangement of Aminomethyl Cyclopropyl Ketones

Heterocycles ◽  
1977 ◽  
Vol 6 (9) ◽  
pp. 1569 ◽  
Author(s):  
Hideo Nemoto ◽  
Hideharu Seto ◽  
Tetsuji Kametani
Keyword(s):  
Thermal Rearrangement ◽  
Cyclopropyl Ketones

scholarly journals Competitive thermal and photochemical processes in cyclopropylketone rearrangements. II. Thermal isomerization of spiro[n.2]alkan-2-ones

1978 ◽  
Vol 56 (6) ◽  
pp. 808-813 ◽  
Author(s):  
Prabhaker G. Khazanie ◽  
Edward Lee-Ruff
Keyword(s):  
Thermal Isomerization ◽  
Thermal Rearrangement ◽  
Type Ii ◽  
Vibrational States ◽  
Photochemical Processes ◽  
Cyclopropyl Ketones

Conformationally-rigid methyl-substituted cyclopropyl ketones with a suitably disposed γ-hydrogen undergo thermal type II reactions efficiently. Comparison of yields of these rearrangements with their photochemical analogs suggest that photochemical type II reactions arise from excited vibrational states. In the absence of a suitably disposed γ-hydrogen, and if strain factors permit, such systems undergo oxovinylcyclopropane to dihydrofuran rearrangement. The inertness of these systems to undergo such thermal rearrangement increased on going from cyclohexanone to the cyclopentanone series.

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