Heteroarylation alkyl Grignard reagents

B. Iron-catalyzed Arylation and Heteroarylation of Alkyl Grignard Reagents 610... 

In 2002, Figad re and coworkers reported the mono-reduction of 2-aryl (or heteroaryl)-1,1-dibromo-l-alkenes (Scheme 23). The reaction is achieved with one equivalent of isopropylmagnesium chloride in the presence of iron(III) acetylacetonate. Pure ( )-alkenyl bromides are obtained. With two equivalents of alkyl Grignard reagent, the mono-substituted product is obtained in moderate yield. 

TABLE 6. Cross-coupling between alkyl Grignard reagents and aryl or heteroaryl chlorides, triflates, and tosylates... 

PHEP-type ligands, since, through activation to the bis(phosphonic dichlorides) they react with a large variety of aryl, heteroaryl or alkyl Grignard reagents to provide the bis(phosphane oxides), which then are reduced to the diphosphanes (cf. [56] and literature cited therein). 

Although aryl chlorides are not usually reactive enough to couple efficiently with alkyl-coppers, heteroaryl chlorides often couple quite well. For example, the most efficient way of alkylating chlorinated phenanthrolines and quinolines, and both 2- and 3-substitued pyridines involves the use of Grignard reagents and copper salts (equation 51)73. 

Miller, J. A., Dankwardt, J. W. (2003). Nickel catalyzed cross-coupling of modified alkyl and alkenyl Grignard reagents with aryl- and heteroaryl nitriles activation of the C—CN bond. Tetrahedron Letters, 44, 1907-1910. 

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