Analogy of Coupled Reactions

That the rate of metabolism of several components may be speeded up when they are metabolized together over what would occur if they are acted on separately is also indicated in the increased rate of alcohol 

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The consecutive reaction of vinyl halides and alkenes with activated methylene systems [42] in the presence of a palladium catalyst and phase-transfer catalyst results from the addition of the methylene carbanion with the initially formed Heck product (Scheme 6.31) an intramolecular version of the reaction leads to the formation of bicycloalk-l-enes (Scheme 6.31) [42], The analogous combined coupling reaction of iodoarenes and activated methylene compounds with non-conjugated dienes under similar conditions forms the monoalkene (Scheme 6.31) [43]. 

In analogy with Eqs. 1.50 and 2.5, the overall surface ligand-exchange reactions in Eqs. 3.46, 3.53, 3.56, 3.65, 3.66, and 4.15b can be dissected into steps by applying the concept of the Eigen-Wilkins-Wemer mechanism, discussed in Section 2.1. Following this perspective, one would decompose the overall surface complexation reaction in Eq. 4.15b into a set of coupled reactions (cf. Eq. 1.50) ... 

When furan or substituted furans are subjected to classic oxidative coupling conditions [Pd(OAc)2 in refluxing HOAc], 2,2 -bifuran and 2,3 -bifuran are the major and minor products, respectively [25, 26], Similar results are observed for the arylation of furans using Pd(OAc)2 [27]. The oxidative couplings of furan or benzo[/j]furan with olefins also proceed analogously [28]. These types of coupling reactions, however, have limited synthetic utility since they all consume at least one equivalent of palladium acetate. 

Suggested mechanisms of coupling reaction of phenol derivative of P-lactam analogs were presented in Fig. 15. 

A mechanical analog for coupled reactions. We can make the smaller weight move upward (a nonspontaneous process) by coupling it with the falling of a larger weight... 

It should also be mentioned that an analogous cross-coupling reaction between vinybc teUurides and alkynylzinc reagents is also possible using 5mol% of NiCl2(dppe) (dppe, l,4-bis(diphenylphosphino)ethane) in refluxing THF [224], The formation of 310 showcases this reaction (Scheme 4.71). 

Although analogous to the direct coupling reaction, the catalytic cycle for the carbonylative coupling reaction is distinguished by an insertion of carbon monoxide into the C-Pd bond of complex A (see A—>B, Scheme 31). The transmetalation step-then gives trans complex C which isomerizes to the cis complex D. The ketone product E is revealed after reductive elimination. 

Analogous electron transfers from the substrate to the electrophilic reagent will be discussed in the context of the azo coupling reaction (Sec. 12.8). 

The occurrence of arenediazo alkyl and aryl ethers as intermediates has been discussed since 1870, when Kekule and Hidegh postulated that in the azo coupling reaction of benzenediazonium salts with phenol, 4-phenylazophenol is formed via the diazo phenyl ether. The analogous problem for diazo methyl ethers was first discussed by von Euler (1903). 

Another example of a [2s+2sh-1c+1co] cycloaddition reaction was observed by Barluenga et al. in the sequential coupling reaction of a Fischer carbene complex, a ketone enolate and allylmagnesium bromide [120]. This reaction produces cyclopentanol derivatives in a [2S+2SH-1C] cycloaddition process when -substituted lithium enolates are used (see Sect. 3.1). However, the analogous reaction with /J-unsubstituted lithium enolates leads to the diastereoselective synthesis of 1,3,3,5-tetrasubstituted cyclohexane- 1,4-diols. The ring skeleton of these compounds combines the carbene ligand, the enolate framework, two carbons of the allyl unit and a carbonyl ligand. Overall, the process can be considered as a for-... 

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