Peterson reaction variations

Several variations of the Peterson reaction have been developed for synthesis of alkenylsilanes.80 -P-Arylvinylsilanes can be obtained by dehydration of (3-silyloxy alkoxides formed by addition of lithiomethyl trimethylsilane to aromatic aldehydes. Specific Lewis acids have been found to be advantageous for the elimination step.81... 

On the other hand, in the Peterson reaction between a-silyl benzyl anions 11 and benzaldehyde, the ratio of the E- and Z-isomers of the product, stilbene, depends on the size of the silyl group, and it is insensitive to the counterion, the solvent, added salts, variation of the carbanion-forming base, or the temperature (Scheme 2.10) [29, 34, 35]. 

Alai/r[(Z)-CF=C]-Pro containing N, 0-diacylhydroxamic acid type protease inhibitors have been prepared as shown in Scheme 18 [63,64], The synthesis is based upon the use of fert-butyl-a-fluoro-trimethylsilylacetate in a variation of the Peterson olefination procedure to construct the necessary functionalized fluoroolefin. Treatment of 51 with 4 equiv. of lithium diisopropylamide (LDA) and 6equiv. of chlorotri-methylsilane at 78°C formed 52 in 71% yield. The key step is the Peterson olefination reaction of the TBDMS-protected 2-(hydroxymethyl)cyclopentanone (53) with tert-butyl-a-fluoro-a-trimethylsilylacetate (52). The fluoroolefin product was obtained as a mixture of (Z) (E) isomers (54). Separation of the double-bond isomers by column chromatography provided (Z) isomer (54) in 43% yield. Further... 

Gajewski, J. J. Peterson, K. B. Kagel, J. R. Huang, Y. C. J. Transition-statestructure variation in the Diels-Alder reaction from secondary deuterium kinetic isotope effects. The reaction of nearly symmetrical dienes and dienophUes is nearly synchronous, 7. Am. Chem. Soc. 1989, 111, 9078-9081. 

There is another variation of fluoride ion induced Peterson-type reaction that utilizes two silyl groups. The reactions between bis(trimethylsilyl)methyl derivatives 157 and carbonyl compounds using fluoride ion as a catalyst give the corresponding alkenes (Scheme 2.99) [281-283]. This reaction is usefiil for many bis(trimethylsilyl)methane derivatives, bearing a variety of substituents, with many ketones and aldehydes. As regards the stereoselectivity of the reaction, E- and Z-isomers are mostly produced in equal amounts. 

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