Organolithium compounds heterocycles

The reaction of tnfluoromethyl-substituted A -acyl umnes toward nucleophiles in many aspects parallels that of the parent polyfluoro ketones Heteronucleophiles and carbon nucleophiles, such as enarmnes [37, 38], enol ethers [38, 39, 40], hydrogen cyanide [34], tnmethylsilylcarbomlnle [2,47], alkynes [42], electron-nch heterocycles [43], 1,3-dicarbonyl compounds [44], organolithium compounds [45, 46, 47, 48], and Gngnard compounds [49,50], readily undergo hydroxyalkylation with hexafluoroace-tone and amidoalkylation with acyl imines denved from hexafluoroacetone... 

The synthesis of oxygen- and nitrogen-containing heterocyclic compounds by anionic cyclization of unsaturated organolithium compounds has been reviewed recently. " Broka and Shen reported the first intramolecular reaction of an unstabilized a-amino-organolithium compound using reductive lithiation of an A,5-acetal derived from a homoaUylic secondary amine (Scheme 21). Just one example was reported treatment with lithium naphthalenide gave the pyrrolidine product, predominantly as the cis isomer. 

Coldham and coworkers have shown that the asymmetric deprotonation protocol can be used to regioselectively alkylate the 5-position of imidazolidines (Scheme 35). The process is used as part of a sequence that results in asymmetric alkylation of 1,2-diamines with high stereoselectivity. The yields are limited, in this case, by the barrier to rotation around the carbamate C—N bond. Thus, only the amide rotamer having the carbonyl group syn to C-5 of the heterocycle is deprotonated. There are several examples in this review where this limitation is possible whether it is a factor or not may depend on the temperature at which amide bond rotation occurs versus the stability of the organolithium compound. In this case, the barrier to amide bond rotation was determined as 16.6 kcalmoD at 60 °C. 

Apart from nucleophilic substitution reactions, the chemistry of the halo derivatives of the 7r-deficient heterocycles is fairly similar to that of aromatic halides. Thus, heterobiaryls can be prepared by the Ullman reaction, and Grignard reagents and organolithium compounds can be prepared, although in many instances, and especially with Grignard reagents,... 

Andrzej Jozwiak received his M.Sc. degree in 1979 and Ph.D. degree in 1985 from University of Lodz under the supervision of Professor Jan Epsztajn. After postdoctoral research with Professor Alan R. Katritzky at the University of Florida (Gainesville, USA) in 1989, he completed habilitation thesis at the University of L6di and received his D.Sc. degree in 1997. He was appointed associate professor at the University of Lodz in 2005. His research interests are the heterocyclic chemistry and application of organolithium compounds in organic synthesis. 

Mustafa and co-workers investigated the reaction of 2V-sulfonyl-1,2-benzisothiazolinones with Grignard reagents66 and organolithium compounds.87 In either case the heterocyclic ring is broken and a tertiary alcohol is formed [Eq. (8)]. 

Organomagnesium compounds usually resemble organolithium compounds in their reactions with nitrogen heterocyclic aromatic compounds [E, G], but they generally give inferior results for preparative purposes. Thus, as in the case of organolithium compounds, addition normally occurs at the 2-position of pyridine, and subsequent elimination or oxidation gives the 2-substituted pyridine [1] ... 

B. Reductive Opening of Heterocycles as a Source of Functionalized Organolithium Compounds... 

Hydroboration of alkenes (185) with dibromoborane gives alkyldibromoboranes (186) which are easily converted into dioxaborinanes (187) (Scheme 25). These heterocycles also provide a convenient entry to aldehydes (189) through the addition of lithiated a-methoxy thioethers <83JA6285>. Unsym-metrical borinate esters (191) can be prepared from these boronates through the addition of organolithium compounds (cf. (190)) followed by treatment with acetyl chloride <850M1788,... 

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