Olefin synthesis Peterson reaction

Scheme 2.19 provides some examples of the Peterson olefination. The Peterson olefination has not been used as widely in synthesis as the Wittig and Wadsworth-Emmons reactions, but it has been used advantageously in the preparation of relatively... 

These P elimination reactions have been used in an olefine synthesis called the Peterson olefination reaction which is analogous (and sometimes superior) to the Wittig reaction. The Peterson olefination reaction involves the addition of an a-silyl carbanion to an aldehyde or ketone to give P-hydroxysilane, followed by P-elimination to give the olefine. 

Four-membered heterocyclic systems have been postulated to be involved as intermediates along the reaction pathway in a number of systems allowing olefin synthesis. This is the case of the Wittig reaction (phosphorus) and a family of related reactions the boron-Wittig (boron), the Peterson (silicon) 44 and the Peterson-type reactions (germanium, tin, lead). 5,l46 11 these systems,... 

Two interesting processes, typical for a-silylcarbanions, are worth mentioning. One concerns the reaction of 328 with carbonyl compounds (for example benzaldehyde), in the course of which 330 is formed. This reaction is the gas-phase analogue of the Peterson olefin synthesis (reaction 135)159. 

Stereoselectivity. See Asymmetric induction Axial/equatorial-, Cis/trans-, Enantio-, Endo/exo- or Erythro/threo-Selectivity Inversion Retention definition (e.e.), 107 footnote Steric hindrance, overcoming of in acylations, 145 in aldol type reactions, 55-56 in corrin synthesis, 261-262 in Diels-Alder cyclizations, 86 in Michael type additions, 90 in oiefinations Barton olefination, 34-35 McMurry olefination, 41 Peterson olefination, 33 in syntheses of ce-hydrdoxy ketones, 52 Steric strain, due to bridges (Bredt s rule) effect on enolization, 276, 277, 296, 299 effect on f3-lactam stability, 311-315 —, due to crowding, release of in chlorophyll synthesis, 258-259 in metc-cyclophane rearrangement, 38, 338 in dodecahedrane synthesis, 336-337 in prismane synthesis, 330 in tetrahedrane synthesis, 330 —, due to small angles, release of, 79-80, 330-333, 337... 

This reaction was first reported by Peterson in 1968. It is a two-step synthesis of olefin involving the addition of an a-silyl carbanion to a carbonyl compound to form y3-silyl alcohol (or /3-hydroxy silane) and the elimination of silol. Therefore, this reaction is generally known as the Peterson olefination. In addition, this reaction is also referred to as the Peterson reaction " and Peterson elimination. Occasionally, the Peterson olefination is also called the Peterson alkenation or Peterson alkenylation. ... 

Silicon-stabilized anions can be put to various uses, among which is the formation of olefins (Peterson reaction), and the 1-phenylthio-l-trimethylsilyl-alkanes required as precursors can also be used in a synthesis of aldehydes. Some of the chemistry reported this year relating to such compounds is shown in Schemes 20 and 21. ... 

Alkene formation reactions are important tools in organic synthesis, and a variety of methodologies have been devised for the conversion of carbonyl compounds into alkenes. The Peterson reaction, developed by D. J. Peterson in 1968, is one of the most important and widely used methods for the conversion of carbonyl compounds into alkenes [1). The Peterson reaction is usually defined as the formation of an alkene from an a-silyl carbanion and a carbonyl compound (Scheme 2.1). The intermediately formed y -hydroxyalkylsilanes are frequently isolated when carban-ions without an anion-stabilizing group are used, and the subsequent alkene formation process from j8-hydroxyalkylsilanes is specifically referred to as Peterson elimination . The term the Peterson reaction is often used to mean the Peterson elimination process as well. The term Peterson olefination is often employed as an alternative to Peterson reaction . 

Peterson Olefination review . Synthesis 1984, 384 Organic Reactions 1990, 38 1. 

Chapters 1 and 2 focus on enolates and other carbon nucleophiles in synthesis. Chapter 1 discusses enolate formation and alkylation. Chapter 2 broadens the discussion to other carbon nucleophiles in the context of the generalized aldol reaction, which includes the Wittig, Peterson, and Julia olefination reactions. The chapter and considers the stereochemistry of the aldol reaction in some detail, including the use of chiral auxiliaries and enantioselective catalysts. 

The Peterson olefination presents a valnable alternative to the Wittig reaction. It has the advantage to allow for a simple control of the alkene geometry. Its applicability in synthesis depends on the availability of the reqnired silanes. ... 

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... 

Apart from the Takai method and titanium reagents such as 15, silyl reagents 16 and 17 frequently find application in the synthesis of vinylic silanes from carbonyl compounds. Reagent 16 can be utilized with aldehydes and non-enolizable ketones in a reaction analogous to the Peterson olefination Reagent 17 also reacts successfully with enolizable ketones.6... 

Wittig olefination reaction ( the phosphorus way ) has been a very popular reaction in organic synthesis. However, it is now in competition with Peterson/Chan olefination reaction327 ( the silicon way ). Formally, this latter involves the formation of a (3-silyl heteroatomic anion, which in the absence of an electrophile undergoes a (3-shift of the silyl moiety to the heteroatom (usually oxygen) with final elimination of silylated heteroatomic anion and formation of the olefin. 

The acid or base elimination of a diastereoisomerically pure p-hydroxysilane, 1, (the Peterson olefination reaction4) provides one of the very best methods for the stereoselective formation of alkenes. Either the E- or Z-isomer may be prepared with excellent geometric selectivity from a single precursor (Scheme 1). The widespread use of the Peterson olefination reaction in synthesis has been limited, however, by the fact that there are few experimentally simple methods available for the formation of diastereoisomerically pure p-hydroxysilanes.56 One reliable route is the Cram controlled addition of nucleophiles to a-silyl ketones,6 but such an approach is complicated by difficulties in the preparation of (a-silylalkyl)lithium species or the corresponding Grignard reagents. These difficulties have been resolved by the development of a simple method for the preparation and reductive acylation of (a-chloroalkyl)silanes.7... 

The well-known Peterson olefination reaction has been utilized in the synthesis of several unusually substituted methylenecyclopropenes The precursor methoxycyclo-propenyl triflates can be obtained as stable crystalline salts by addition of methyl triflate to the appropriate cyclopropenone (equation 75). The reaction of these triflates with a variety... 

The Peterson olefination is a connective alkene synthesis and represents a useful alternative to the Wittig reaction. The precursors for the Peterson olefination are 3-hydroxy-alkyltrimethylsilanes which undergo P-elimination of trimethylsilanol under basic or acidic conditions to furnish stereodefined alkenes. This olefination method is especially valuable for the preparation of terminal and exo-cyc ic double bonds and for the methylenation of hindered ketones where the Wittig reaction is problematic. Also, the... 

In the final stages of the total synthesis of (+)-brasilenyne by S.E. Denmark and co-workers, the introduction of the (Z)-enyne side chain was accomplished with the Peterson olefination. The aldehyde was treated with lithiated 1,3-b/s(triisopropylsilyl)propyne at low temperature followed by slow warming of the reaction mixture to ambient temperature to give a 6 1 (Z ) ratio of the desired enyne. 

The synthesis of alkylidene and allylidene cyclopropanes reported in this section takes advantage of the availability 77 78,81 a-82) of l-(l-silyl) cyclopropyl carbinols from a-lithio cyclopropylsilanes and carbonyl compounds. It, however, suffers from the sometimes modest yields obtained when ketones are involved (Schemes 21 a, 47) in the Peterson olefination reaction 77,78,81a) (Schemes 21, 48). This reaction seems much more difficult to achieve than when straight-chain analogs are involved and resembles the cases of allenes 1211 and chlorocyclopropenes120) reported by Chan. For example, thionyl chloride alone is not suitable for that purpose 77,136) but further addition of tetra-n-butylammonium fluoride (20 °C, 15 hrs) leads to the formation of undecylidene cyclopropane77,136 in 46% yield from the corresponding l-(l-silyl)cyclopropyl... 

The Peterson olefination is a two-step process for the formation of alkenes from an a-silylcarbanion and an aldehyde or ketone. The first step is an addition reaction that affords both syn and anti p-hydroxysilanes. The stereochemistry is then controlled during the elimination step by using either an acid or a base. Reviews Kano, N. Kawashima, T. In Modem Carbonyl Olefination-Methods and Applications Takeda, T. Ed. Wiley-VCH Weinheim, 2004 Chapter 2 The Peterson and Related Reactions, pp. 18-103. (b) Kelly, S. E. In Comprehensive Organic Synthesis Trost, B. M. Fleming, 1., Eds. Pergamon Oxford, 1991 Vol. 1, Chapter 3.1 Alkene Synthesis, pp. 731-737. (c) Ager, D. J. Org. React. 1990, 38, 1-223. (d) Ager, D. J. Synthesis 1984, 384-398. 

Keeney, A, Nieschalk, J., and O Hagan, D., The synthesis of a-monofluorovinylphosphonates by a Peterson type olefination reaction, J. Fluorine Chem., 80, 59, 1996,... 

Gais, H.-J., Schmiedl, G., and Ossenkamp, R.K.L., Total synthesis of (-i-)-3-oxacarbocyclin. Part 1. Retrosynthesis and asymmetric olefination through Horner-Wadsworth-Emmons, Peterson and Martin reactions, Liebigs Ann., 2419, 1997. 

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