Silylated and germylated cyclopropanones

Зайцева, Г. С.; Bogdanova, G. S.; Baukov, Yu. I.; Lutsenko, I. F.

doi:10.1016/s0022-328x(00)80778-0

Cited by 19 publications

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“…Synthesis of precursors to cation 15 (R = Ph) (Scheme ) involved the cyclobutanone 18 , which is readily available by addition of excess diazomethane to trimethylsilyl ketene . Addition of phenylmagnesium bromide to this silylated cyclobutanone gave a mixture of alcohols 19 and 20 .…”

Section: Resultsmentioning

confidence: 99%

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γ-Silyl Cyclobutyl Carbocations

Creary

Kochly

2009

J. Org. Chem.

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A series of 3-trimethylsilyl-1-substituted cyclobutyl trifluoroacetates have been prepared and reacted in CD(3)CO(2)D. Rate data indicate that the substrates with the trimethylsilyl group cis to the leaving group react with assistance due to gamma-silyl participation. Rate enhancements range from a factor of 209 for alpha-phenyl-substituted cations to 4.6 x 10(4) for alpha-methyl-substituted cations to >10(10) for the unsubstituted gamma-trimethylsilylcyclobutyl cation. Acetate substitution products are formed with net retention of stereochemistry. These experimental studies, as well as B3LYP/6-31G* computational studies, are consistent with the involvement of carbocations where the rear lobe of the gamma-Si-C bond interacts strongly with the developing cationic center. Solvolytic rate studies, as well as computational studies, suggest that the secondary gamma-trimethylsilylcyclobutyl cation is even more stable than the beta-trimethylsilylcyclobutyl cation, i.e., the gamma-silyl effect actually outweighs the potent beta-silyl effect. Although computational studies suggest the existence of certain isomeric cations, where the front lobe of the Si-C bond interacts with the cationic center, solvolytic evidence for the involvement of these front lobe stabilized cations is less compelling.

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Section: Resultsmentioning

confidence: 99%

“…A pure sample of 3-trimethylsilylcyclobutanone, 18 , was isolated by silica gel chromatography of the mixture of 2- and 3-trimethylsilylcyclobutanone . Ketone 18 (191 mg) was dissolved in 2 mL of ether and the solution was cooled to 0 °C.…”

Section: Methodsmentioning

confidence: 99%

γ-Silyl Cyclobutyl Carbocations

Creary

Kochly

2009

J. Org. Chem.

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“…Other pathways to the cyclopropanone hemiacetal consist of photochemical decarbonylation of tetramethylcyclobutanedione in ethanol19 or methanol20 giving the corresponding tetramethylcyclopropanone hemiacetals and isobutyrates (eq 5) and electroreduc-0 ^-C-OR (5) 20-30% 70-80% 0 products (8) ion, its ligands, and on the concentration and addition rate of the reactants.24 On the other hand, cyclopropanone dimethyl acetal fails to react under the same condition suggesting that the hydroxyl group of the hemiacetal is essential for the oxidation and is the first site of attack by the electrophilic metallic ion. 26 Arylcyclopropanone hemiacetals undergo oxidation by a variety of oxidizing agents.…”

Section: %mentioning

confidence: 99%

Cyclopropanone hemiacetals

Salaün¹

1983

Chem. Rev.

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“…An alternative pathway involves ionization to produce the 2-oxidopentadienylic cation 11 , which can then undergo conrotatory 4π electrocyclic closure , to generate the cyclopentenone product. A third pathway, proceeding via the cyclopropanone intermediate 10 , cannot be excluded, particularly in view of the finding that diazomethane adds to (trimethylsilyl)ketene to generate (trimethylsilyl)cyclopropanone in good yield 1 …”

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confidence: 99%