Cross-coupling carbene + alkene

C-C bond formation can be favored over /3-hydride elimination by changing the nature of the catalyst. Hence, cyclizations can be mediated by iridium carbene complexes resulting from a formal intramolecular cross-coupling of the alkene with an. s -C-H bond (Equation (40)). 

Bis(adamantylimido) compounds, with monomeric chromium(VI) complexes, 5, 348 Bis(alkene) complexes conjugated, Rh complexes, 7, 214 mononuclear Ru and Os compounds, 6, 401 -02 in Ru and Os half-sandwich rj6-arenes, 6, 538 with tungsten carbonyls and isocyanides, 5, 685 Bis(u-alkenylcyclopentadienyl) complexes, with Ti(II), 4, 254 Bis(alkoxide) nitrogen-donor complexes, with Zr(IV), 4, 805 Bis(alkoxide) titanium alkynes, in cross-coupling, 4, 276 Bis(alkoxo) complexes, with bis-Cp Ti(IV), 4, 588 Bis[alkoxy(alkylamino)carbene]gold complexes, preparation, 2, 288... 

A very recent report highlights the cross-coupling of Fischer carbene complexes with ethyl diazoacetate to give push-pull alkenes such as 106 at ambient temperature using 15 mol-% CuBr as a catalyst (Scheme 46) [98] alkyl-, alkenyl- (105) and arylcarbenes provided comparable good chemical yields. 

Abstract In this chapter, alkene synthesis based on the reactiOTi of //-tosylhydrazones is described. The reactivity of tosylhydrazones is determined by either the acidity of a-proton and hydrazcMie proton or the electropositivity of the carbon of C=N bond. This leads to diverse reactivities and a series of N-tosylhydrazone-based olefination methodologies. Both non-catalytic and transition metal-catalyzed olefinations from Al-tosylhydrazones are introduced in this chapter. Most of the transition metal-catalyzed reactions proceed via metal carbene transformations. The synthesis of alkenes through Pd-catalyzed cross-coupling reactions of Af-tosylhydrazones is particularly attractive and will be discussed in detail. 

Keywords Alkene synthesis Cross-coupling Metal carbene /V-Tosylhydrazones... 

In the last 15 years we have developed two new catalytic reactions between the same parent substances, i.e. silylative coupling (SC) (also called tmns-silylation or silyl groiq> transfer) and cross-metathesis (CM) of alkenes, which have provided an universal route for the synthesis of well-defined molecular compounds with vinylsilicon functionality. While the cross-metathesis is catalyzed by well-defined Ru and Mo carbenes, the silylative coupling is catalyzed by complexes initialing or generating M-H or M-Si bonds (where M = Ru, Rh, Ir). For recent reviews see Refs. [4-6],... 

While vinylsilanes undergo productive cross-metathesis (Mo and Ru carbenes) with allyl-substituted functionalized alkenes, their effective transformation with derivatives containing a fimctionalized group attached directly to a carbon -carbon double bond can be achieved only via silylative coupling catalyzed by metal complexes containing (or generating) M-H and/or M-Si bonds (M = Ru, Rh, Ir). 

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