Nickel-Catalyzed Cross-Trimerization of Alkynes

Based on previous results for the 1 2 cross-trimerization of alkynes [50], Ogata, Fukuzawa et al. [51] developed the first 1 1 1 cross-trimerization of alkynes employing Ni(cod)j/2PPhj (10mol%) as the catalyst. A high 

SCHEME 3.22 Palladium-catalyzed aminosulfonylation of boronic acids. Proposed mechanism. 

SCHEME 3.23 Palladium-catalyzed multicomponent reaction via Buchwald-Hartwig amination process. 

41 avoiding the steric hindrance between the aryl fragment and the metal center. Next, insertion of symmetric alkyne 

42 into the Ni—C bond of the sterically hindered intermediate XXI and subsequent reductive elimination afford product 43. 

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