Negishi cross-coupling reactions natural products

The Negishi cross-coupling reactions have been showcased as key steps in the synthesis of many natural products and in structure-activity relationship drug discovery programmes. 

The selection of natural products shown in Figure 5-15 display the possibilities of the Negishi cross-coupling reaction. ... 

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Netherton M, Fu GC (2005)Palladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 NicolaouKC, KingNP, He Y (1998) Ring-Closing Metathesis in the Synthesis of EpothUones and Polyether Natural Products. 1 73-104 Nishiyama H (2004) Cyclopropanation with Ruthenium Catalysts. 11 81-92 Noels A, Demonceau A, Delaude L (2004) Ruthenium Promoted Catalysed Radical Processes toward Fine Chemistry. 11 155-171... 

Banwell has developed a new approach to the core associated with several members of the lamellarin class of marine natural products. This approach utilized some interesting pyrrole arylation reactions including a Negishi. cross coupling of the iodopyrrole 46 followed by a double-barrelled Heck cyclization of the resultant arylpyrrole 47 yielding the core structure 48... 

Magnolol 217 (Scheme 14.42), a simple antiviral BIPOL isolated from the bark of Magnolia officinalis, is readily constructed by the Negishi cross-coupling of 214 with its corresponding iodide 215, both readily obtained by DoM-transmetallation or DoM-iodination reaction, to yield 216, which, upon simple hydrolysis, affords the natural product 217 [158]. 

A direct and satisfactory procedure for tertiary alkyl-alkynyl coupling has been developed by Negishi and Baba, who used trialkynylaluminums readily obtainable from the corresponding alkynyllithiums and anhydrous AICI3 [92]. For instance, tris(l-hexynyl)aluminum underwent a remarkably clean reaction with 1-adamantyl bromide to produce cross-coupled product 96 in 96 % yield. It is noteworthy that the reaction enables novel geminal alkyl-alkynylation of ketones this reaction should find a considerable application in natural product synthesis (Sch. 60). 

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