Substituent effects in the SE2′ protonolysis of allyltins

Kuivila, Henry G.; Verdone, Joseph A.

doi:10.1016/s0040-4039(00)90339-3

Cited by 36 publications

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References 8 publications

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“…First, the aldehyde ( 1 ) is activated by the carboxylic acid through hydrogen bonding. Then, in general, the resulting electrophile intermediate I could attack 2b on C 1 (adjoining tin atom) or C 3 through two pathways, namely S E 2 and S‘ E 2, respectively . It is known that strong Lewis acids mediating crotylation proceed by a S‘ E 2 (open) mechanism to afford the γ-adduct ( 7 ) exclusively. , Therefore, it may be understood that the carboxylic acids, as Lewis acids, could promote the crotylation through a S‘ E 2 mechanism predominantly ( III , path B, Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Efficient Allylation of Aldehydes Promoted by Carboxylic Acids

Zhao

2005

J. Org. Chem.

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A variety of carboxylic acids have been screened for mediating the allylation of aldehydes with allytributyltin in different solvents. A novel, general, and practical method of allylation of aldehydes promoted by carboxylic acids under mild reaction conditions has been developed. Among them, p-nitrobenzoic acid afforded high to quantitative yields of the homoallylic alcohol products, and can be easily recovered after workup by aqueous HCl. Glyoxylic acid self-catalyzed the allylation without adding any other promoter or catalyst to give the corresponding allylation product in good yield. The regioselectivity of the crotylation of aldehydes is tunable by controlling the acidity of the carboxylic acids. The crotylation of aldehydes produced the alpha-adduct as major products in moderate to good yields with CF(3)CO(2)H as a promoter. A possible mechanism for the allylation is also discussed.

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Section: Resultsmentioning

confidence: 99%

Efficient Allylation of Aldehydes Promoted by Carboxylic Acids

Zhao

2005

J. Org. Chem.

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By Hydrogen Halides

Bellama¹

1989

Inorganic Reactions and Methods

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Solution‐polymerized rubbers with superior breakdown properties

Uraneck

Short

1970

J of Applied Polymer Sci

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synopsisNatural rubber breaks down readily during mechanical mixing, and rubber processors have traditionally made good use of this property. Emulsion SBR rubber breaks down with greater difficulty and some polybutadiene rubbers, not a t all. This paper describes a new class of solution elastomers, both polybutadiene and butadiene-styrene copolymers, designed to undergo controlled breakdown during processing. They can be made by reacting active polymer lithium molecules with tin compounds to produce star-shaped molecules containing a central tin atom connected by tin-carbon bonds. When such a product is mixed with an organic (stearic) acid, some of the tin bonds are ruptured and the desired breakdown occurs. The extent of breakdown can be controlled by the mixing conditions and the amount of organic acid employed. There are numerous applications in which these rubbers process more easily and display better properties than conventional rubbers. Data on breakdown under various conditions and physical properties of the compounds are presented in this paper.I n addition to the superior processing characteristics, these products introduce a new concept of elastomer breakdown. The breaking of a polymer chain at a carbon-tin bond by a chemical agent eliminates the need for breaking carbon-carbon bonds by mechanical energy or oxidative degradation. Accomplishing polymer breakdown by a controlled reaction, rather than by conventiofial means, has long been an unsolved problem of the rubber industry.

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Substituent effects in the SE2′ protonolysis of allyltins

Cited by 36 publications

References 8 publications

Efficient Allylation of Aldehydes Promoted by Carboxylic Acids

Efficient Allylation of Aldehydes Promoted by Carboxylic Acids

By Hydrogen Halides

Solution‐polymerized rubbers with superior breakdown properties

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