Cross-coupling carbonylative

Moderate yields of acids and ketones can be obtained by paHadium-cataly2ed carbonylation of boronic acids and by carbonylation cross-coupling reactions (272,320,321). In an alternative procedure for the carbonylation reaction, potassium trialkylborohydride ia the presence of a catalytic amount of the free borane is utilized (322). FiaaHy, various tertiary alcohols including hindered and polycycHc stmctures become readily available by oxidation of the organoborane iatermediate produced after migration of three alkyl groups (312,313,323). 

As described above, our synthetic strategy involves the convergent construction of the central cyclopentanone ring with a carbonylative cross-coupling reaction and a photo-Nazarov cyclization reaction (Chart 2.2). The electrophilic coupling component 51 was synthesized by an intramolecular Diels-Alder reaction [34] and the nucleophilic coupling component 52 by a vinyiogous Mukaiyama aldol reaction [35]. 

Indolylborates 142 (Z = Me, Boc, OMe), available via regioselective C-2 lithiation of indoles 141, are capable of undergoing palladium-catalyzed carbonylative cross-coupling... 

Carbonylative cross-coupling reaction between triarylbismuth(V) compounds and organostannanes is smoothly catalyzed by PdCl2 under 1 atm CO at room temperature (Scheme 48) [34]. Not only arylstannanes, but also heteroaryl-, alkynyl-, and vinyltributylstannanes were employed efficiently. 

Scheme 48 Carbonylative cross-coupling reaction of Ar3BiX2 with organostannanes...

Alkyl halides possessing / -hydrogens are usually poor substrates for carbonylative cross-coupling due to competitive / -hydride elimination/ Allyl chlorides can be used in carbonylative cross-coupling with allylstannanes/ phenyl-, 3-furyl, or vinylstannanes " to afford allylketones in modest to good yields. Divinylketones can be accessed through the reaction of vinylstannanes with vinyl iodides or vinyl triflates, with the latter requiring the addition of LiCl. Synthetic potential of this method has been proved in the formation of macrocyclic ketone jatrophone. In the reaction of vinyl triflates with tetramethyltin or aryltrimethylstannanes the additional activation by ZnCle is required. 

A unique example of selective combination of cross-coupling and carbonylative cross-coupling in the presence of chelated Pd complex was described (Equation (3)). ... 

Carbonylative cross-coupling of iodoarenes and aryl triflates with g< ///-fluorovinyltributylstannane takes place smoothly in a standard system, with triflate substrates requiring the addition of tetrabutylammonium iodide (Equation (4)). ... 

The addition of LiCl and Cul, and triphenylarsine as ligand are required to suppress side-reactions in the carbonylative cross-coupling of geminally substituted alkenyl triflate in the synthesis of sarcodictyin. Stereochemical configuration of the double bond of organotin compound was completely lost in this reaction (Equation (5)). " ... 

Lithium triethyl(l-methylindolyl-2)borate has been introduced as a convenient source of indolyl residue for carbonylative cross-coupling with aryl iodides, alkenyl iodides, or triflates. The reaction requires elevated CO pressure and high loading of catalyst (5mol.%) (Equation (15)). Aryl and alkenyl bromides, as well as aryl iodides... 

Carbonylative cross-coupling of various iodonium salts bearing transferable aryl, heteroaryl, alkenyl, alkynyl residues with phenylboronic acid takes place under mild conditions giving the respective ketones in high yields (Equation (16)). The yields of competing cross-coupling do not exceed 8%. 

Carbonylative cross-coupling of arenediazonium salts with arylboronic or styrylboronic acids was realized using a... 

The synthesis of radioactive ketones with C in carbonyl was achieved by carbonylative cross-coupling of aryl iodides or triflates with methyl-, phenyl-, or 2-thienylboronic acids under elevated pressure of CO. To ensure fast reaction, harsh conditions were used. Interestingly, under such conditions the addition of a base is not necessary (Equation (18))." ... 

A prototypical study for this section has been obtained as early as in 1983 for carbonylative cross-coupling of the mixture of aryl iodide and alkyl iodide in the presence of Zn metal and palladium catalyst. This system apparently works due to differences of reactivity of aryl versus alkyl iodide toward metallation by Zn. Further studies were rather scarce to involve only preformed functionalized alkylzincs. Carbonylative cross-coupling of functionalized organozinc reagents with allylic esters and GO (1 atm) can be carried out in THF in the presence of HMPA, which suppresses side-reactions (Scheme 4). ... 

Similar protocol has been successfully used for the preparation of / -aroylaminoacids (Equation (22)), including protected L-kynurenine. Careful exclusion of air is crucial for the success, as in the presence of oxygen, the formation of symmetrical ketone formed from organozinc reagent competes with carbonylative cross-coupling. ... 

Besides, iodoarenes aryliodonium salts were used as electrophilic coupling partners in the synthesis of ynones. The carbonylative cross-coupling can be run in aqueous DME in the presence of Pd(OAc)2 and Gul as co-catalyst and NaHG03 as a base at 30 °G. ... 

In the presence of appropriate organometallic compounds, the trapping of organopalladium intermediate can be followed by the carbonylative cross-coupling pathway (Scheme 15)/" The cascade can be applied to the construction of heterocycles (Scheme 16). 

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