Grignard coupling

Another area of interest to the industrial sector is the development of a more efficient synthesis of biaryl compounds. This has been accompHshed using a Ni(II)-cataly2ed Grignard coupling reaction with an aryl haUde (86—89). 

This imine is stable to the Fe(acac)3-catalyzed Grignard coupling of aryl halides. 

K. Tamao, S. Kodama, I. Nakajima, M. Kumada, A. Minato, and K. Suzuki, Nickel-phosphine complex-catalyzed Grignard coupling — II Grignard coupling of heterocyclic compounds, Tetrahedron, 38 3347-3354, 1982. 

Banning,43 who synthesized 1,4-naphthalene oligomer using a Grignard coupling reaction with 1,4-dibromonaphthalene as the starting material. The IR spectra of PNT-N prepared in this work all have this absorption at 699 cm-1. Films collected from different VDP reactions always exhibit this specific absorption, between 696-699 cm-1. 

Figure 18.8. Silane dendrimers via hydrosilylation and Grignard coupling...

The (—)-anisomycin work is presented in Scheme 35. Its key step centered around the formation of a pyrrolidine ring that possessed all three of the asymmetric centers present in the target this was done by nucleophilic displacement of a 3-tosyloxy function in an appropriately functionalized 6-amino-6-deoxy-p-i.-talose derivative, whose 1,2-diol was later released and oxidatively cleaved with sodium periodate. Grignard coupling, O-acetylation, and catalytic hydrogenation then furnished the desired natural-product target. 

Hocek used Suzuki coupling and the iron catalyzed Grignard-coupling methodology, introduced by Furstner,5 to functionalise dihalopurine derivatives selectively. 2,6-Dichloropurines underwent cross-coupling in the... 

In particular, H-H PIBs with molecular weights in the range of 3-10 k Dalton were prepared by the Grignard coupling polymerization of 2,2,3,3-tetramethyl-l,4-dibromobutane with copper(I) tris-(triphenylphosphino)bromide as catalyst (20). This catalyst is also referred to as the Yamamoto catalyst (21). The reaction is sketched out in Figure 6.2. 

Figure 6.2 Grignard Coupling Polymerization (19) Table 6.2 End Chain Functionalization...

M. Malanga and O. Vogl, Head-to-head polymers. XXIV. Synthesis of head-to-head polyisobutylene by grignard coupling reaction, ]. Polym. Sci., Part A Polym. Chem., 21(9) 2629-2648,1983. 

SCHEME 76. Mechanism of Ni-catalyzed Grignard coupling reaction. 

Arylation, olefins, 187, 190 Arylketimines, iridium hydrogenation, 83 Arylpropanoic acid, Grignard coupling, 190 Aspartame, 8, 27 Asymmetric catalysis characteristics, 11 chiral metal complexes, 122 covalently bound intermediates, 323 electrochemistry, 342 hydrogen-bonded associates, 328 industrial applications, 8, 357 optically active compounds, 2 phase-transfer reactions, 333 photochemistry, 341 polymerization, 174, 332 purely organic compounds, 323 see also specific complexes Asymmetric induction, 71, 155 Attractive interaction, 196, 216 Autoinduction, 330 Axial chirality, 18 Aza-Diels-Alder reaction, 220 Azetidinone, 44, 80 Aziridination, olefins, 207... 

Brown et al. 3S2) have recently emphasised the role of defect structures in heterocyclic polymers. They point out that the reported doped conductivities of these polymers may vary by as much as six orders of magnitude depending on the preparation procedure. They have applied the laser desorption method, discussed earlier for polyphenylene, to a range of polyheterocycles. Unlike polyphenylene, there was evidence for incomplete desorption and rearrangement of evaporated molecules. The results show that polymers prepared by Grignard coupling vary in their extent of bromination, the nature of the terminal species and the extent of formation of cyclic, polynuclear contaminants. 

A regio- and stereocontrolled copper catalyzed allylic alkylation has been recently reported [219]. With the thiophenolate copper catalyst 150, the Grignard-coupling reaction provided only the y-allylated product in quantitative yield, albeit with modest enantioselectivity (Eq. 8E.33). 

To improve the preparative method of phospha sugars from sugar starting materials [21,22], the Arbzov reaction and Grignard coupling reaction have been applied to a reaction of 1,4-dibromobutane. The reaction of 1,4-dibromobutane (53) with dimethyl phenylphosphonite to give ethyl (4-bromobutyl)phenylphosphinate (54) and successive intramolecular substitution of the 4-bromo substituent with phosphinyl anion affords 1-phenyl -phospholane 1-oxide (56a) in 40% yield. It can also be prepared from... 

The 2- and 3-phospholenes are prepared by the McCormack reaction and are good candidates as starting materials for the preparation of five-and six-membered phosphorus heterocycles [25-27]. From l-methoxy-3-methyl-2-phospholene 64 or l-methoxy-2,3-diacetoxy-3-methylphospholane 67, l-aryoxy-3-methyl-2-phospholenes 66a-c (Scheme 19), or l-aryoxy-2,3-diacetoxy-3-methylphospholane 69 (Scheme 20) with a substituted phenyl group at phosphorus, or l-aryl-3-methyl-2-phospholenes 71a-g (Scheme 21) are prepared by a substitution reaction and/or a Grignard coupling reaction [28,29]. 

The trans-selectivity of the Grignard coupling can be increased by addition of copper salts such as CuCN or dilithium tetrachlorocuprate. 

---