Carbonylation 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. 

Several Pd-catalyzed domino processes start with a Tsuji-Trost reaction, a pal-ladation of alkynes or allenes [5], a carbonylation [6], an amination [7] or a Pd(II)-cat-alyzed Wacker-type reaction [8]. A novel illustrious example of this procedure is the efficient enantioselective synthesis of vitamin E [9]. 

Several Pd-catalyzed methods for the synthesis of a-substituted carbonyl compounds Method I (this section, i.e., Sect. III.2.14.1, and Sect. V.2.1 (the Tsuji-Trost reaction))... 

For a-aUylation and a-propargylation of carbonyl compounds, however, the Tsuji-Trost reaction and related reactions discussed extensively in Part V (Sect. V.2.1) provide a wide range of very satisfactory procedures. Although the Tsuji-Trost reaction has mostly been carried out by using extrastabilized enolates, such as acetoacetates and malonates, subsequent decarboxylation provides more usual a-substituted ketones (Scheme 3). 

Contrary to earlier notions that the Pd-catalyzed a-allylation of carbonyl compounds would be limited to those carbonyl compounds that are extrastabilized (the Tsuji-Trost reaction), the use of Zn, B in the forms of BRjK or Li + 2 BR3, where R = Et, and so on, Si, and Sn has been shown to permit the use of those enolates of ordinary ketones, aldehyde esters, and so on, where the pATj of the carbonyl compounds may be 20. In some cases, however, even lithium enolates can provide satisfactory results. Since most of the enolates mentioned above are derived via alkali metal enolates containing Li, Na, or K, these parent enolates should be tested before converting or modilying them with reagents containing other metals. 

In the first catalytic Tsuji-Trost reaction, allylic acetate 19 was readily converted into product 21 in good yield. Following this precedent, numerous examples of this allylation reaction have been reported using activating groups such as carbonyl, sulfonyl, cyano, nitro, aryl, olefmic, imino, etc. Readers are referred to the many comprehensive reviews on the topic for extensive examples of the Tsuji-Trost reaction in synthesis. ... 

Although it is mechanistically different from the Tsuji-Trost allylation, indirect allyla-tions of ketones, aldehydes, and esters via their enolates are briefly summarized here. Related reactions are treated in Sect V.2.1.4. Pd-catalyzed allylation of aldehydes, ketones, and esters with aUyhc carbonates is possible via the Tr-allylpaUadium enolates of these carbonyl compounds. Tr-AUylpalladium enolates can be generated by the treatment of silyl and stannyl enol ethers of carbonyl compounds with allyl carbonates, and the allylated products are obtained by the reductive elimination of the Tr-allylpalladium enolates. 

In addition to the applications reported in detail above, a number of other transition metal-catalyzed reactions in ionic liquids have been carried out with some success in recent years, illustrating the broad versatility of the methodology. Butadiene telomerization [34], olefin metathesis [110], carbonylation [111], allylic alkylation [112] and substitution [113], and Trost-Tsuji-coupling [114] are other examples of high value for synthetic chemists. 

The use of palladium(II) 7i-allyl complexes in organic chemistry has a rich history. These complexes were the first examples of a C-M bond to be used as an electrophile [1-3]. At the dawn of the era of asymmetric catalysis, the use of chiral phosphines in palladium-catalyzed allylic alkylation reactions provided key early successes in asymmetric C-C bond formation that were an important validation of the usefulness of the field [4]. No researchers were more important to these innovations than Prof. B.M. Trost and Prof. J. Tsuji [5-10]. While most of the early discoveries in this field provided access to tertiary (3°) stereocenters formed on a prochiral electrophile [Eq. (1)] (Scheme 1), our interest focused on making quaternary (4°) stereocenters on prochiral enolates [Eq. (2)]. Recently, we have described decarboxylative asymmetric allylic alkylation reactions involving prochiral enolates that provide access to enantioenriched ot-quatemary carbonyl compounds [11-13]. We found that a range of substrates (e.g., allyl enol carbonates,... 

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