Stille Carbonylative Cross-Coupling

Scheme 6 Carbonylative Stille cross-coupling of vinyl halides, triflates, and sulfonyl chlorides.

Another approach developed by the Vogel group relies on a carbonylative Stille cross-coupling between stannylated glucal derivative 410 and enol triflate 412 derived from isolevoglucosenone [152] (O Scheme 80). 

A concise synthesis of photoactivatable 4-benzoyl-L-phenylalanines and related peptides was described by G. Ortar et al. using a carbonylative Stille cross-coupling as the key step. Surprisingly, when the coupling was attempted with tyrosine triflate derivatives, it proved to be unsuccessful. However, 4-iodo-phenylalanine derivatives reacted smoothly under standard conditions to give the corresponding 4-benzoyl derivatives. 

Palladium(0)-catalyzed coupling reactions - i. e. the Heck and Sonogashira reactions, the carbonylative coupling reactions, the Suzuki and Stille cross-coupling reactions, and allylic substitutions (Fig. 11.1) - have enabled the formation of many kinds of carbon-carbon attachments that were previously very difficult to make. These reactions are usually robust and occur in the presence of a wide variety of functional groups. The reactions are, furthermore, autocatalytic (i.e. the substrate regenerates the required oxidation state of the palladium) and a vast number of different ligands can be used to fine-tune the reactivity and selectivity of the reactions. 

The copolymer 174 was prepared from diaUcyl thienylated benzodithiophene (173) and perfluororalkyl-carbonyl substituted thieno[3,4-h]thiophene (172) monomers (Scheme 41). Thus, reaction of thieno[3,4-6]thiophene-2-carbaldehyde (150) with heptadecafluorooctyl iodide in the presence of methyllithium to form 170 was followed by oxidation with Mn02 giving ketone 171. Bromination with two equivalents of NBS furnished dibromide 172, and this was Stille cross-coupled with 173 in the presence of Pd2(dba)3 to obtain the copolymer 174 [63]. 

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. 

Cross-coupling reactions 5-alkenylboron boron compounds, 9, 208 with alkenylpalladium(II) complexes, 8, 280 5-alkylboron boron, 9, 206 in alkyne C-H activations, 10, 157 5-alkynylboron compounds, 9, 212 5-allylboron compounds, 9, 212 allystannanes, 3, 840 for aryl and alkenyl ethers via copper catalysts, 10, 650 via palladium catalysts, 10, 654 5-arylboron boron compounds, 9, 208 with bis(alkoxide)titanium alkyne complexes, 4, 276 carbonyls and imines, 11, 66 in catalytic C-F activation, 1, 737, 1, 748 for C-C bond formation Cadiot-Chodkiewicz reaction, 11, 19 Hiyama reaction, 11, 23 Kumada-Tamao-Corriu reaction, 11, 20 via Migita-Kosugi-Stille reaction, 11, 12 Negishi coupling, 11, 27 overview, 11, 1-37 via Suzuki-Miyaura reaction, 11, 2 terminal alkyne reactions, 11, 15 for C-H activation, 10, 116-117 for C-N bonds via amination, 10, 706 diborons, 9, 167... 

Good yields are achieved for five- and six-membered ring cyclizations by the intramolecular cross-coupling reaction of haloalkenes [139, 152], but the scope of reaction is still limited by the availability of the haloalkenes, particularly because of the absence of a simple method for preparing cyclic haloalkenes from ketone precursors. The ready availability of triflates from carbonyl compounds now offers a valuable tool for the annulation of ketones (Scheme 2-56) [160]. 

Pd-catalyzed Stille carbonylative cross-coupling Pd-catalyzed coupling of organostannanes and alkenyl-or aryl halides and CO to form ketones. 436... 

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. 

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