Aryl compounds crossed

Gund, P. (1972) Guanidine, trimethylenemethane and y-delocalization, Can arylic compounds have aromatic stability. Journal of Chemical Education, 49, 100-103 Klein, J. (1983) Directive effects in allylic and benzylic polymetalations the question of u-stabilization, y-aromaticity and cross-conjugation. Tetrahedron, 39, 2733-2759. 

These cross-coupling reactions are coupling reactions of aryl compounds with aryl compounds, aryl compounds with olefins, olefins with olefins, etc., as shown in Fig. 8.4. The cyclometalation reactions of aryl substrates with aryl compounds give aryl-aryl coupling reaction products, as shown in Eq. (8.29). Stanford et al. [138]... 

In an early example of this reaction aryl and benzyl zinc halides were coupled with aryl halides (equation 40) (102). Alkynyl zinc compounds cross-couple with aryl halides (iodides or bromides) in the presence of a Pd catalyst (equation 41) (103) or alkynyl iodides can be coupled with aryl and alkenyl zinc compounds (equation 42) (100). 

The cross-coupling of aromatic and heteroaromatic rings has been carried out extensively[555]. Tin compounds of heterocycles such as oxazo-lines[556,557], thiophene[558,559], furans[558], pyridines[558], and seleno-phenes [560] can be coupled with aryl halides. The syntheses of the phenylo.xazoline 691[552], dithiophenopyridine 692[56l] and 3-(2-pyridyl)qui-noline 693[562] are typical examples. 

An intramolecular palladium(o)-catalyzed cross-coupling of an aryl iodide with a trans vinylstannane is the penultimate maneuver in the Stille-Hegedus total synthesis of (S)-zearalenone (142) (see Scheme 38).59 In the event, exposure of compound 140 to Pd(PPh3)4 catalyst on a 20% cross-linked polystyrene support in refluxing toluene brings about the desired macrocyclization, affording the 14-membered macrolide 141 in 54% yield. Acid-induced hydrolysis of the two methoxyethoxymethyl (MEM) ethers completes the total synthesis of 142. 

It has been shown that cross-coupling reactions constitute a very mild method to introduce different alkyl and aryl groups to the most active C-3 position of the pyrazinone ring [26]. The broadly functionahzed 2-azadiene system of the title compounds was studied in cycloaddition reactions with various electron-reach and electron-poor dienophiles to provide highly substituted heterocycles [24]. 

Radical-mediated silyldesulfonylation of various vinyl and (a-fluoro)vinyl sulfones 21 with (TMSlsSiH (Reaction 25) provide access to vinyl and (a-fluoro)vinyl silanes 22. These reactions presumably occur via a radical addition of (TMSlsSi radical followed by /)-scission with the ejection of PhS02 radical. Hydrogen abstraction from (TMSlsSiH by PhS02 radical completes the cycle of these chain reactions. Such silyldesulfonylation provides a flexible alternative to the hydrosilylation of alkynes with (TMSlsSiH (see below). On oxidative treatment with hydrogen peroxide in basic aqueous solution, compound 22 undergoes Pd-catalyzed cross-couplings with aryl halides. 

Palladium And/Or Copper-Mediated Cross-Coupling Reactions Between 1-Alkynes And Vinyl, Aryl, 1-Alkynyl, 1,2-Propadienyl, Propargyl And Allylic Halides Or Related Compounds. A Review, Rossi. R. Carpita, A. Beilina, F. Org. Prep. Proceed. Int., 1995, 27, 129... 

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