Tsuji decarboxylation

The Pd-catalyzed reaction of propargyl electrophiles with carbon monoxide is a convenient route to allenyl carboxylic acid derivatives. In 1986, Tsuji et al. reported the Pd-catalyzed decarboxylation-carbonylation of propargyl carbonates under a CO at-... 

Similarly, a double functionalization can be reached when an activating group is present in close vicinity to the triple bond. Tsuji et al. have discovered that with a diphosphine palladium(O) complex, a carbonate function in the a-position of the alkyne provides by decarboxylation a palladium methoxy species on which the alkyne moiety can be isomerized into an al-lenyl a -bonded group. CO insertion in the Pd - C bond, reductive elimination with the methoxy group and further cyclization with incorporation of a second CO molecule give rise to the corresponding cyclopentenone as shown in Scheme 21 [127]. 

By 1984, the palladium-catalyzed aUyhc alkylation reaction had been extensively studied as a method for carbon-carbon bond formation, whereas the synthetic utility of other metal catalysts was largely unexplored [1, 2]. Hence, prior to this period rhodium s abihty to catalyze this transformation was cited in only a single reference, which described it as being poor by comparison with the analogous palladium-catalyzed version [6]. Nonetheless, Yamamoto and Tsuji independently described the first rhodium-catalyzed decarboxylation of allylic phenyl carbonates and the intramolecular decarboxylative aUylation of aUyl y9-keto carboxylates respectively [7, 8]. These findings undoubtedly laid the groundwork for Tsuji s seminal work on the regiospecific rho-... 

TROST CHEN Decarboxylation 390 TSCHUGAEFF Olefin synthesis 391 TSUJI - TROST Allylation 392 Tsu)i 402... 

Enol carbonates react with alkylating agents in the presence of a palladium catalyst. The decarboxylative alkylation of allyl enol carbonates to the corresponding aUylcyclohexanone derivatives is known as the Tsuji alkylation. An asymmetric version of this reaction has been reported. The same reaction can be done using enolate anion and aUylic acetates with a palladium catalyst. ... 

Heck carbonylation involving the oxidative addition of aryl halides is not applicable to aliphatic halides, since alkyl halides react directly with nucleophiles. Tsuji developed a process of carbonylating allyl carbonates to form carboxylic esters by palladium-catalyzed carbonylation that is applicable to aliphatic substrates [60]. The process probably involves (a) the oxidative addition of allyl carbonates to Pd(0) species to form r/ -allyl palladium species, (b) CO insertion into the allyl-Pd bond to give acylpalladium species, (c) decarboxylation of the carbonate ligand to give alkoxide, and (d) liberation of butenoate esters by combination with the alkoxides as shown in Scheme 1.21. 

The studies of the origin of GHB in A. bisporus demonstrated the involvement of the shikimate-chorismate pathway (Scheme 102). Labeling experiments showed an efficient incorporation of H- and C-labeled shikimic acid 439,440) and C-labeled chorismic acid 441) into the 4-hydroxyaniline moiety of GHB. It was also demonstrated that in the biochemical shikimate-4-hydroxyaniline conversion in the mushroom, amination occurred at the 4 position of one of the carboxylic acid intermediates [initially assumed to be shikimic acid 439)]. Additionally, the p-aminobenzoic acid, which proved to be 441) the precursor of 4-hydroxyaniline, underwent a decarboxylative hydroxylation catalyzed by a FAD-dependent monooxygenase 4-aminobenzoate hydroxylase in the presence of NAD(P)H and O2. This enzyme from A. bisporus was recently purified to homogeneity by Tsuji et al. 442). 

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). 

Example 7, Tsuji-Trost decarboxylation-dehydrogenation sequence ... 

Other Methods. - One of the most important and flexible approaches to ketone synthesis involves the manipulation of 6-keto-esters. Tsuji et al. have reported that the use of allyl keto-esters, which are prepared from ketones and diallyl carbonate or allyl chloroformate, offer advantages over more common esters in that the ester hydrolysis/decarboxylation step... 

Despite the effort involved in the synthesis of dbdot, its complexes are gaining increasing popularity [19]. An example was recently published by Han et al. [20], which nicely illustrates the enhanced thermal stability of these complexes (Scheme 11.7). This reaction is a decarboxylative allyfic substitution (Tsuji reaction), which can also be carried out with C and N nucleophiles. 

In 1979, Tsuji s group [51] reported an alternative approach to macrolactonization. Inspired by their previous success in the preparation of recifeiolide and 9-decanolide, the authors envisioned that the dimethyl ether of zearalenone (6) could be obtained via olefination using the co-iodoalkyl phenylthioacetate 7 (Scheme 7.2). The Michael addition of diethyl malonate (11) to 10 followed by decarboxylation afforded an ethyl ester, which was reduced to alcohol and converted into the tosylate 12. Wacker-Tsuji oxidation of the terminal olefin was then followed by reduction of the ketone and conversion of the tosylate into iodide to provide 9. This was... 

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,... 

Tsuji et al. found that by decarboxylation, propargylic carbonates form aUenylpaUa-dium complexes, which readily undergo a variety of transformations [97]. Thereafter, propargyl derivatives such as propargyl halides, acetates, and carbonates have been used widely in palladium catalysis. 

Pd-mediated ketone allylation was first introduced by Tsuji et al. Generally, the method involved the decarboxylation of allyl p-keto esters or the use of enol derivatives along with a Pd° catalyst to give rise to the... 

Rhodium-catalyzed allylic substitution processes generally proceed in a stereospecific manner. After initial reports by Tsuji [107], extensive studies by Evans have resulted in the development of a reliable and general method for the stereoselective preparation of useful building blocks [39, 108-111]. With Wilkinson s catalyst in the presence of phosphites, Evans has showcased the rhodium-catalyzed allylation of numerous substrate classes. Thus, substitution of the carbonate in 125 with malonate 124 furnished 126 dr =26 1), which was subsequently subjected to decarboxylation and io-dolactonization reaction [112] to afford 127 (dr >30 1, Scheme 14.20) [109]. 

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