KOCHI Cross coupling

KOCHI Cross coupling 208 KOENIGS KNORR G KOHLER Isoxazole-N-oxide tynthesB 210 KOLBE Electrolysis 211 KOLBE SCHMIDT Sabcyhc acid synthesis 2 KONAKA Oxidizing reagent 213... 

Our group has recently developed an alternative method for alkyl-(hetero)aryl- as well as aryl-heteroaryl cross coupling reactions catalyzed by iron salts.3 4 This methodology was inspired by early reports of Kochi et al.5>6 on iron-catalyzed cross coupling of vinyl halides and is distinguished by several notable advantages. 

In 1971, a year before the groups of Corriu and Kumada [5] independently reported the groundbreaking work on the topic of nickel-catalyzed cross-coupling reactions of aryl and vinyl halides with Grignard reagents, Tamura and Kochi described an iron-catalyzed vinylation reaction of Grignard reagents with vinyl halides (Scheme 5.1) [6]. 

Scheme 5.1 Stereospecific iron-catalyzed cross-coupling reaction reported by Kochi and Tamura in 1971.

Since the discovery of transistion metal-catalyzed cross-coupling reactions by the groups of Kochi, Kumada and Corriu in the early 1970s, impressive progress has been achieved in the development of these methods into a synthetically indispensable... 

Tamura and Kochi studied the cross-coupling reactions of alkyl halides with alkyl Grignard reagents catalyzed by silver compounds first [422, 426, 427]. The coupling of primary alkyl halides with primary Grignard reagents resulted in a mixture... 

As can be seen in the following examples, both Cu and Cu" salts such as CuCl. CuBr, Cul, CuCN, Cu(acac)2, and Li2CuCl4 (known as Kochi s catalyst [22]), introduced at 0.2 10% to a Grignard or a substrate are most typical for these reactions. The choice of copper salts is dependent on their intrinsic reactivities, as well as on physical properties, such as solubility and ease of handling. For example, Li2CuCl4 is soluble in tetrahydrofuran (THF) and is frequently quite useful to obtain clean cross-coupled products. An added Cu species is considered to be reduced to Cu in situ by the Grignard reagent to participate in the catalytic cycle [see Eq. (36)]. 

Alkenylation of Grignard reagents (4, 236). Neumann and Kochi have reported extensive studies of the synthesis of olefins by cross-coupling of Grignard reagents with alkenyl halides ... 

Scheme 1.14 Iron-catalyzed cross-coupling with alkenyl halide 39 (Kochi, 1971).

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