Carbon monoxide organolithium

We recently demonstrated that organolithium reagents formed by directed metallation of pivaloylanilines would react rapidly with carbon monoxide at 0°C or room temperature to form high yields of dioxindoles (Fig. 16) (ref. 30). This... 

Ureas of anilines 84 can also be lithiated" The products are generally very hard to cleave, but quenching the intermediate organolithiums 85 with carbon monoxide generates acyllithiums 86 which cyclize to give isatins 87 (Scheme 40)" . 

Acyl anions (RC(=0)M) are unstable, and quickly dimerize at temperatures >-100 °C (Section 5.4.7). These intermediates are best generated by reaction of organolithium compounds or cuprates with carbon monoxide at -110 °C and should be trapped immediately by an electrophile [344—347]. Metalated formic acid esters (R0C(=0)M) have been generated as intermediates by treatment of alcoholates with carbon monoxide, and can either be protonated to yield formic acid esters, or left to rearrange to carboxylates (R0C(=0)M —> RC02M) (Scheme 5.38) [348]. Related intermediates are presumably also formed by treatment of alcohols with formamide acetals (Scheme 5.38) [349]. More stable than acyl lithium compounds are acyl silanes or transition metal acyl complexes, which can also be used to perform nucleophilic acylations [350],... 

Organomagnesium compounds are less reactive than organolithium compounds [E] towards carbon monoxide and metal carbonyls. The initial reaction with carbon monoxide is similar — addition to give an acylmagnesium compound ... 

As described in Section II.A, the tandem sequence reaction of organolithium compounds with carbon monoxide followed by reaction with suitable electrophiles provides an useful tool for the preparation of diphenyldialkyl carbinols, and the reaction could be easily extended to produce substituted cyclic ethers in a one-pot synthesis. Thus, by carrying out the carbonylation of phenyllithium in the presence of conveniently substituted chloroalkyl bromides, Br(CH2)3+ Cl, at -78 °C, the oxo-lithiated intermediates 243 are obtained and cyclized to 244 by warming up the reaction mixture (Scheme 74)21. 

The synthetic applications of acyllithiums, generated by reaction of organolithium compounds with carbon monoxide, by treatment with electrophiles started when Nudelman and coworkers found that phenyllithium reacted with carbon monoxide in the presence of alkyl bromides to yield diphenylalkylcarbinols24,27. a-Hydroxy-a-phenylacetophenone was also obtained resulting from the dimerization of the carbene intermediate of type 3. In the absence of electrophiles a,a-diphenylacetophenone was obtained in 94% yield, attributed to the dimerization of the corresponding aroyl anion radical28. 

Since HLiCO and LiCOH are intramolecular solvated organolithium species - in contrast to LiH - it is a question of interest, whether oligomerization is still a strongly exothermic process. Therefore again ab initio calculations on HF/6-3 IG level of theory are used to explore geometries and reaction enthalpies of dimers and tetramers, when the lithium to carbon monoxide ratio is 1 1. 

Carbonylation of Organolithium Compounds with Selenium and Carbon Monoxide... 

It is known that carbon monoxide is attacked by organolithium and Grignard reagents at the carbon to generate acylmetallic moieties [2a,b]. However, these are too reactive to be manipulated further for the practical synthetic use except for a few specially designed systems, e.g. Scheme 8.4 involving intramolecular silyl migration of silylacetyl lithium [2b],... 

The remedy to avoid such mixtures is in situ trapping (Scheme 1-169). The organolithium is added slowly through a syringe needle across a rubber septum into a THF/DEE/PEN (tetrahydrofliran/diethyl ether/pentanes) solution saturated with carbon monoxide and and kept in the -135 to -110 °C range. In addition, this solution contains a suitable electrophile such as chlorotrimethylsilane, a carbonyl compound, or dicyclohexylcarbodiimide. Under such conditions, the acyllithium 225 is intercepted... 

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