Transition-Metal-Catalyzed Carbonylative Domino Reactions

Transition-Metal-Catalyzed Carbonylative Domino Reactions 

Xiao-Feng Wm, Helfried Neumann, and Matthias Seller 

Transition-metal catalysts play an ever-increasing and important role in modem chemistry [3]. Numerous transition-metal-catalyzed coupling reactions have been developed and applied in the total synthesis of natural products, such as the Suzuki reaction, the Negishi reaction, the Heck reaction, and many others [4]. Interestingly, the power of transition-metal catalysts is even more visible in the area of domino reactions, where terms such as palladium walking show the value of transition metals in bond formations. 

Domino Reactions Concepts for Efficient Organic Synthesis, First Edition. Edited by Lutz F. Tietze. 

In order to assess the value of domino and carbonylation reactions, and also to differentiate them from normal transition-metal atalyzed carbonylation reactions, in this chapter we will only describe the carbonylation reactions that produce at least three bonds under the same conditions. 

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Transition-Metal-Catalyzed Carbonylative Domino Reactions... 

Transition-Metal-CatalYzed Carbonylative Domino Reactions 119 pd) O... 

In summary, we have summarized representative examples of transition-metal-catalyzed carbonylative domino reactions. In the area of carbonylations, palladium, rhodium, and cobalt are still the main actors. The abihty of palladium catalysts in carbonylative cross-coupling, rhodium catalysts in carbonylative C-H activation, and cobalt catalyst in carbonylative reactions with unsaturated bonds is impressive. 

Transition metal-catalyzed transformations are of major importance in synthetic organic chemistry [1], This reflects also the increasing number of domino processes starting with such a reaction. In particular, Pd-catalyzed domino transformations have seen an astounding development over the past years with the Heck reaction [2] - the Pd-catalyzed transformation of aryl halides or triflates as well as of alkenyl halides or triflates with alkenes or alkynes - being used most often. This has been combined with another Heck reaction or a cross-coupling reaction [3] such as Suzuki, Stille, and Sonogashira reactions. Moreover, several examples have been published with a Tsuji-Trost reaction [lb, 4], a carbonylation, a pericyclic or an aldol reaction as the second step. 

An alternate synthesis of enantiopure (—)-diversonol was recently reported by Tietze et al. using an enantioselective transition-metal-catalyzed domino process (Scheme 14.48). Key step in the synthesis is the formation of a chromane with concomitant introduction of the quaternary stereocenter at C-4a with 96% ee using a domino Wacker/carbonylation/methoxylation reaction in the presence of (S,S)-Bn-BOXAX (310) as ligand [73]. In this reaction phenol 308, containing an alkene moiety, was treated with catalytic amounts of Pd(tfa)2 and 310 in MeOH in the presence of CO and p-benzoquinone the latter is necessary to reoxidize Pd to Pd". One can assume that the first step is an enantiofacial coordination of the Pd" species, which is attacked by the phenolic hydroxyl group to give intermediate... 

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