Alkanes Butyllithium

The a-lithiated sulfides 33 are another class of chiral organometallic reagent, readily available by deprotonation of the parent l-(phcnylthio)alkanes 32 with butyllithium in tetrahydrofuran at - 78 °C. 

Diisopropenylbenzene butyllithium diadduct Bis(a-styryl)phenylene butyllithium diadduct Bis(p-isopropenylphenyl)alkane lithium diadducts... 

Hall U3>, Hsieh 106>, Roovers and Bywater107), Tanlak and co->workers114), and Bordeianu and co-workersI1S) followed the initiation of styrene under polymerization conditions in aromatic or alkane solvents using ethyllithium, z-propyllithium, or isomers of butyllithium. Without exception, these authors found a first power dependency of initiation rate on total active center concentration. Hsieh s results106) and those of Roovers and Bywater 107, also indicate that the first order character for initiation is independent of the degree of association (4 or 6) of the alkyllithium. The first order dependence of the initiation step on total active center concentration is also maintained over the period where cross-aggregated structures, PSLi (RLi)x, are present. 

Metallation is never a competing reaction even for those selenoacetals derived from aromatic aide hydes (Scheme 81). Only in the case of phenyl selenoacetals derived from formaldehyde and acetaldehyde are the corresponding l-metallo-l,l-bis(seleno)alkanes produced (Scheme 82). In fact these compounds arise from the metallation of the selenoacetals not by the butyllithium but by the a-selenoal-... 

Treatment of the silylamines la-le with -butyllithium in equimolar ratio in M-hexane gives the hydridosilylamides R2(H)SiNLiSiR 3 2a-2e in nearly quantitative yield (Eq. 4). Compounds 2a-2e are colorless, crystalline solids that can be recrystallized fi om -alkanes. 

A further interesting example is the use of l,l-di(phenylthio)med)yllithium to open an epoxide followed by a Grob fragmentation process as shown in Scheme 56 (entry b). The reaction of 1,1-di-(thio)methyllithium with epoxides has also been used - in the one-pot synthesis of l,l-di(thio)cyclopropanes involving an intramolecular cyclization of the 7-tosyloxydi(phenylthio)alkylli-thium. This intramolecular alkylation reaction proceeds even more efficiently than its intermolecular version, and allows the synthesis of a large variety of l,l-di(thio)cyclopTDpanes from 3-chloro- and 3-phenylthio-l,l-di(thio)alkanes and n-butyllithium in THF (Scheme 57 and Scheme 58). 

Related reactions involve l-metallo-l,l-di(arylseleno)- ° and l-lithio-l,l-di(methyl-seleno)-alkanes (Scheme 81 Scheme 82), - 1-lithio-l-phenylseleno-l-phenyltelluromethane (Scheme 78, entry h) as well as 1-trimethylsilyl-l-arylselenomethyllithiums (Scheme 78, entries a-f)74.>06.353.375 gnj j.giyi homolog - gnd 1-trimethylsilyl-l-methylselenoalkyllithiums (Scheme 78, entry g). Intramolecular cyclizations of 3-halo-l,l-di(seleno)alkanes7 77 and of 3-tosyloxy-1,1,1-tri(seleno)alkane7 with LDA and n-butyllithium respectively lead to the corresponding l,l-di(seleno)cy-clopropanes (Scheme 82, entries b-g). These in turn have proved to be valuable precursors of 1-seleno-I-cyclopropyllithiums (Scheme 8, entry e Section 1.3.2.1.1). 

Epoxides were involved as intermediates when 1-cyclopropyl-1-[tris(methylsulfanyl)meth-yl]alkan-l-ols were subjected sequentially to butyllithium (1 equivalent) and CUCIO4 4MeCN (2 equivalents) and underwent rearrangement to thioesters with the carbonyl /i to the cyclopropane ring, e.g. formation of 7. A l-cyclopropyl-2-diazoalkanol reacted in a similar fashion on treatment with rhodium(II) acetate. ... 

Cycloalkanones Five- and six-membered cyclic ketones can also be prepared by reaction of methyl methylthiomethyl sulfoxide (1) and a 1, co-dihalo-( or ditosyloxy)alkane (2) in the presence of 2 eq. of base (potassium hydride or w-butyllithium) in THF at -70 to 20°. The product (3) is hydrolyzed to the ketone (4) by acid. Ogura et al. suggest that 2 eq. of base are required because... 

Allylic sulfoxides and sulfones are completely metallated in liquid ammonia by all alkali amides [1]. For metallation in organic solvents, LDA and BuLi are usually applied. The lithiation of allyltrimethylsilane can be conveniently achieved with BuLi TMEDA (or HMPT) or f-BuLi TMEDA (or HMPT) in THF-alkane mixtures [3], As in the case of the sulfur compounds, extension of the unsaturated system leads to an increased acidity. Thus H2C=CHCH=CHCH2SiMe3 can be metallated with the less strongly basic LDA in THF [4], For the metallation of allylic selenides, LDA seems to be the reagent of choice. Butyllithium will presumably attack on selenium. 

Synthesis of Alkanals. Monoalkylation of 3-(phenylsulfo-nyl)propanal ethylene acetal (1) takes place at the position a to the phenylsulfonyl group on successive treatment with butyllithium and then with an alkyl halide. Deprotection of the acetal group and subsequent elimination of benzenesulfinic acid with a base produces the corresponding 2-alkenal (eq 1). ... 

Direct cleavage of thioether derivatives 402 can be performed resulting in alkanes 403 or in the iodo-substituted derivatives 406. lodo-transformations have been known since a publication by Crosby et al. in 1977 [272], Starting from a methyl sulfide resin and following hthiation with -butyllithium, alkylarylthioethers have been synthesized that could be cleaved in 82% yield via the addition of a mixture containing Mel and Nal (Scheme 57). 

However, when vinylic metalation is desired, competing allylic deprotonation may occur. In general, thermodynamic acidity and the kinetic preference for vinylic deprotonation of cyclic alkenes decrease with increasing ring size." The stable alkane-soluble reagent n-Butyllithium-Potassium t-Butoxide-TMEDA in hexane metalates Ethylene with potassium and effects selec-... 

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