Peterson-type reagent

A useful application of the silver-mediated additions is 1,3 -diene synthesis by three-carbon elongation of aldehydes [48,51,53]. The bimetallic reagent 3-trimethylsilyl-l-propenylzirco-nocene chloride (A Scheme 8.23) reacts with aldehydes under the influence of a catalytic amount of Ag+ to give the intermediate zirconocene-alkoxide B, which then undergoes a Peterson-type 1,4-elimination of TMS alkoxide to stereoselectively afford ( )-dienes (fc/Z > 96 4) (Scheme 8.23). A Wittig reaction yields the same products without stereoselectivity (ca. 1 1 mixtures of E- and Z-isomers). 

Selenoaldehydes,2 In the presence of 5-10 mole% of butyllithium, this disilyl selenide converts aldehydes into selenoaldehydes with formation of the disiloxane [(CH,)3SiOSi(CH3),]. The active reagent is presumed to be lithium trimethylsilyl-selenide, (CH3)3SiSeLi, which can be regenerated by a Peterson-type elimination (equation I). 

The Peterson olefination has been also investigated for the introduction of a two-carbon chain as in 132 [39,175,176]. This alternative procedure compares well with the reaction of stabilized Wittig-type reagents [compare both procedures in Ref. 175]. 

The reagent is prepared from the corresponding silane with t-butyllithium. Vinylsilanes. The reaction of 1 with aldehydes or ketones provides vinylsi-lanes via a Peterson-type reaction. 

A method that makes available aromatic and aliphatic aldehyde derived sulfin-imines 47, for the first time, was recently introduced by Davis and co-workers.23,36 This one-pot procedure entails treatment of the Andersen reagent 40 with LiHMDS to generate 44 which subsequently reacts with the lithium methoxide by-product to produce silyl sulfinamide anion 46. Reaction of 46 with the aldehyde in a Peterson-type olefination reaction affords the sulfinimine 47 in >96% ee. This method was highly effective for the preparation of arylidene sulfmamides 47 (R = aryl) which were usually obtained in 60-76% yield although the alkyl counterparts... 

MeSiBCHiMR (M = Si, Sn, Pb, S. Hg). Most of these complex reagents can be prepared by the reaction of Mes2BCH2Li with C1MR . An interesting Peterson-type reaction observed with one of these boranes is shown in equation (I). 

Introduction. The Peterson-type olefination reaction has emerged as an extremely useful method for the preparation of alkenes from carbonyl compounds. Synthetically useful vinylsilanes can be prepared by using the Peterson-type olefination reaction of bis(silyl)methylmetal with carbonyl compounds. Among the various reported bis(silyl)methyhnetals, [bis(2-pyri-dyldimethylsilyl)methyl]lithium is an extremely efficient reagent for the stereoselective preparation of vinylsilane. ... 

For (3-(naphthalen-2-yl)-2,2-bis(trimethylsilyl))oxiran, Peterson-type oleflnation, after or concurrently with the addition of MeCN/ BFs-EtaO, regioselectively gave the (1-trimethylsilylvinyl) amide 243 (Scheme 24.31) in a one step without any other reagents or catalysts. This reaction was accomplished upon stirring of equimolar amounts of the epoxide and boron trifluoride-ether, with an excess of acetonitrUe as solvent, for 24 h at room temperature (155). 

Three different routes to the key compounds for the sila-Peterson elimination, the a-alkoxydisilanes 157, are described in the literature, namely A, reaction of silyllithium reagents with ketones or aldehydes B, addition of carbon nucleophiles to acylsilanes C, deprotonation of the polysilylcarbinols. In addition, method D, which already starts with the reaction of 2-siloxysilenes with organometallic reagents, leads to the same products. The silenes of the Apeloig-Ishikawa-Oehme type synthesized so far are summarized in Table 4. 

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