Stille coupling Tsuji-Trost reaction

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. 

One distinguishes palladium(0)- and palladium(ll)-catalysed reactions. The most common palladium(O) transformations are the Mizoroki-Heck and the cross-coupling transformations such as the Suzuki-Miyaura, the Stille and the Sonogashira reactions, which allow the arylation or alkenylation of C=C double bonds, boronic acid derivates, stan-nanes and alkynes respectively [2]. Another important palladium(O) transformation is the nucleophilic substitution of usually allylic acetates or carbonates known as the Tsuji-Trost reaction [3]. The most versatile palladium(ll)-catalysed transformation is the Wacker oxidation, which is industrially used for the synthesis of acetaldehyde from ethylene [4]. It should be noted that many of these palladium-catalysed transformations can also be performed in an enantioselective way [5]. 

Many transition metal-catalyzed cross-couplings such as the Stille coupling, the Heck reaction, the Suzuki reaction, and the Trost-Tsuji reactions have been carried out in aqueous conditions.In oiu own studies, we recently discovered that various palladium-catalyzed couplings of the above types can be performed in air and water. For example, a highly... 

We conclude that the addition of phosphanes to palladium(II)-NHC complexes is advantageous with respect to reaction times, yield and completion ratio for a wide range of catalytic coupling reactions including Tsuji-Trost, allylic amination, Suzuki-Miyaura, Heck and Stille. 

The field of palladium catalysis is also progressing rapidly. The Tsuji-Trost and Mizoroki-Heck reactions have been mentioned earher, however other C-C coupling reactions (Miyaura-Suzuki, Sonogashira and Stille) are now extensively used in organic chemistry, and the search for non-polluting Sonogashira and Miyaura-Suzuki reactions is being actively pursued. 

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