Transition metal catalysis addition-fragmentations

Some of the most impressive advances in the area of catalytic, enantioselective aldol addition reactions have taken place in the development of catalytic methods for enantioselective acetate aldol additions, a reaction type that has long been recalcitrant. Thus, although prior to 1992 a number of chiral-auxiliary based and catalytic methods were available for diastereo- and enantiocontrol in propionate aldol addition reactions, there was a paucity of analogous methods for effective stereocontrol in the addition of the simpler acetate-derived enol silanes. However, recent developments in this area have led to the availability of several useful catalytic processes. Thus, in contrast to the state of the art in 1992, it is possible to prepare acetate-derived aldol fragments utilizing asymmetric catalysis with a variety of transition-metal based complexes of Ti(IV), Cu(II), Sn(II), and Ag(I). 

Vinylphosphines are a valuable class of compounds with a myriad of applications in organic synthesis and catalysis. Vinylphosphines also have a rich history in coordination chemistry due to the geometry and reactivity of this fragment with transition metal centers [414-420]. The proximity and flexibility of the alkene have been used to generate a host of coordination compounds in which the vinylphosphine is coordinated to the metal center through the phosphorus as well as through the alkene. In addition to providing a unique architecture for disCTCte coordination compounds, vinylphosphines are also valuable linkers in the formation of 3D arrays and coordination polymers [421-424],... 

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