Grignard reagents, reactions palladium-catalysed

In 1999, Ikeda et al. reported a new type of sulfur-oxazoline ligands with an axis-fixed or -unfixed biphenyl backbone prepared in good yields by coupling reactions of methoxybenzene derivatives substituted with a chiral oxazoline and a sulfur-containing Grignard reagent. These ligands were subsequently evaluated for the test palladium-catalysed asymmetric allylic alkylation... 

A convenient reaction of organolithium with easily available thiuram disulfides was reported by Gronowitz et al. [45], and the reaction of Grignard reagents with N,AT-dimethylthiocarbamoyl chloride was found [46] to be nicely catalysed by NiCl2(dppe) to afford thioamides. An analogous route with palladium[II] catalysis allowed Hartke et al. [47] to prepare a number of interesting a-acetylenic thioamides. 

Boronates (i.e. boronic acids and esters) are usually prepared by one of two methods reaction of organo-lithiums or Grignard reagents with a trialkyl borate, usually tri-Ao-propyl borate, or palladium-catalysed boronation. 

CROSS-COUPLING REACTION OF ALKYL HALIDES WITH GRIGNARD REAGENTS IN THE PRESENCE OF 1,3-BUTADIENE CATALYSED BY NICKEL, PALLADIUM, OR COPPER... 

Ni and Pd catalysts were found to be most useful for this purpose [35]. Palladium catalysed reactions show better chemoselectivity, but are restricted to activated aryl bromides while nickel-catalysed processes are more tolerant to steric hindrance of aromatic substituents [36]. These reactions are the best alternative to Ni(0) catalysed high temperature coupling of aryl halides [37]. With stericaly hindered aryl halides generation of a Grignard reagent is recommended. Preferably the component with an ortho substituents should be converted the Grignard compound[38]. 

The Grignard reagents are far more applicable counterparts in the nickel- and palladium-catalysed Kharasch cross-coupling reactions with aryl halides (1, Br, Cl), as well as aryl triflatcs, to give biaryls in moderate to excellent yields [19]. In early... 

Further work on the palladium-catalysed reaction of butadiene with carbonyl compounds, which gives tetrahydropyrans, has been reported. The d-hydroxyaldehydes (237), obtained by the action of alkyl Grignard reagents on glutaraldehyde, form cyclic hemiacetals (238) which may be... 

The required silanes can be formed by the reaction of organolithium species or Grignard reagents with silicon electrophiles, but also by palladium- and rhodium-catalysed coupling reactions (Scheme 2.108). 

---