Tris methyllithium

The other three methods have not been studied extensively. The dimethyl-cadmium route has been used on a 17a-methyl-17 -carboxylic acid. ° The reaction of the acid amide with a Grignard reagent is described only in a Spanish patent,with a high yield claimed, and the methyllithium reaction has apparently been tried only on D-norsteroids. ... 

Reaction of tris(trimethylsilyl)methyllithium 1631 with styrene oxide affords, via 1632 and 1633, the cyclopropane 1634 in 69% yield [25] (Scheme 10.11). The reactions of tris(trimethylsilyl)methyllithium 1631 have been reviewed [26]. 

The combination of equimolar amounts of tris(trimethylsilyl)methyllithium and zinc bromide in a THF/diethyl ether mixture, Scheme 27, furnished tris(trimethylsilyl)methylzinc bromide, as a lithium bromide/ether adduct.43 The compound, which may also be formulated as a lithium alkyldibromozincate, showed no ligand redistribution reactions. It is monomeric in solution and can be treated with 1 equiv. of an organolithium reagent to afford heteroleptic diorganozinc compounds. 

The sequential treatment of tris(/ r/-butylimido)sulfonate with methyllithium and dimethylzinc (Scheme 32) produced an unusual dimethylzinc adduct of hthium-Y-methyl-tri(/< 7/-butylimido)sulfonate 35, shown in Figure 15.80 Here, two imido-nitrogen atoms chelate the lithium ion, while the third one functions as a neutral... 

Cyclopropanation of enones.1 Reaction of an enone with tris(phenylthio)-methyllithium and then with CuOTf (1 equiv.) results in a bis(phenylthio)-cyclopropane (equation I). 

Tris(phenylthio)methyllithium, (QHsS)3CLi (1). Tris(phenylthio)methane is prepared from thiophenol and trimethyl orthoformate. 

Likewise, the lactol 62, obtained by addition of methyllithium to 2,3,5-tri-O-benzyl-D-arabinono-1,4-lactone, underwent a self-condensation reaction in the presence of BF3 OEt2-MeCN, to afford an anomeric mixture of two C-disaccharides 63 and 64 in 93% yield (66). 

The TMEDA and THE complexes of the very sterically crowded methyllithium derivative tris(trimethylsilyl)methyUithium (9, Scheme 1) were studied by multinuclear solid state NMR spectroscopy in combination with solution NMR spectroscopy and X-ray crystallography to reveal the strucmre and dynamic behaviour of the complexes . In the solid state, this complex crystallizes as an ate-complex, with one lithium cation interacting with two substituted methyl anions while the other lithium cation is complexed by two TMEDA ligands. In solution, the afe-complex is partly transformed into solvated monomers or aggregates, depending on the experimental conditions. 

Treatment of tri-(2-thienyl)methane with BunLi in the presence of TMEDA in THF at — 78°C gives exclusively the tri-(2-thienyl)methyllithium (393) (96%) without any nuclear lithiation (92CL703). This lithiation is faster than that of triphenylmethane. Treatment of (393) with primary alkyl halides leads to alkylation at the carbanion center, forming (394). However, secondary alkyl halides give mixture of (394) and (395). 

Some efficient syntheses have been reported such as those of p-hydroxy esters from tris(methylthio)methyllithium and epoxides. The case of a malate derivative from a commercially available chiral epoxide is described [286]. 

Methylaluminum bis(2,6-di-t-butyl-4-methylphenoxide) (MAD, 1) methylal-uminum bis(2,4,6-tri-Ubutylphenoxide) (MAT, 2). The complexes formed from 4-f-butylcyclohexanone and 1 or 2 (3 equiv.) react with methyllithium or CH3MgBr... 

Methyllithium-Methylaluminum bis(2,4,6-tri-t-butylphenoxide), 203 Organolithium reagents, 221 Trityllithium, 338 Boron reagents Alkyldimesitylboranes, 8 Bis(2,4-dimethyl-3-pentyl) tartrate, 36 Chlorodimethoxyborane, 73 Silicon reagents Titanium(IV) chloride, 304 Tin reagents... 

Methyllithium-Methylaluminum bis(2,4,6-tri-/-butylphenoxide), 203 Trichloromethyltitanium, 216 Triisopropoxymethyltitanium, 213 Addition reactions which can be used to prepare secondary alcohols only Dichloro(cyclopentadienyl)methyl-titanium, 219... 

Allylic phosphorus compounds Tris(tetrabutylammonium) pyrophosphate, 338 Allylsilanes t-Butyllithium, 58 Chlorotrimethylsilane-Lithium, 81 Lithium bis(dimethylphenylsilyl)-cuprate, 161 Methyllithium, 188 Trichlorosilane-t-Amines, 322 Allylic sulfur compounds (Phenylsulfonyl)allene, 247 Sodium benzenesulfinate, 289... 

Methyllithium-Methylaluminum bis-(2,4,6-tri-t-butylphenoxide), 203 Methylthiomethyllithium, 192 Nickel chloride-Lithium, 197 Organolithium reagents, 18, 56, 94,... 

Related to jS-diketones are metalla-/ -diketones, whose distinctive chemistry is a recent development. In these, the methine group of a conventional diketonate is replaced with an organometallic moiety such as m-Mn(CO)4, m-Re(CO)4, /<2c-Mn(CO)3(RNC) or C5H5Fe(CO).519 Exemplary is Al Mn(MeCO)2(CO)4 3, which is prepared in a two-step synthesis. Addition of methyllithium to Mn(CO)5COMe forms Li[Mn(MeCO)2(CO)4] which, when treated with aluminum chloride, provides the tris(chelate) compound.520 An X-ray study showed that the MnC202Al ring is essentially planar with Mn—C(acyl) bond distances indicative of a bond order of ca. 1.2. The O—O bite distance, 2.73 A, is about the same as that of acetylacetonate in Al(MeCOCHCOMe)3.521 As in the... 

HYDROXY CARBOXYLIC ACIDS Dicyclohexylborane a -HY DROXY-a, [J-ENONES m-Chloropcrbcnzoic acid y-HYDROXY-a,B-ENONES Potassium peroxomonosulfate. a HYDROXY ESTERS Tris(phenylthio)methyllithium. a-HYDROXY-p-KETO ESTERS ... 

ALKENES 1,3-Dimethyl-2-phenyl-l, 3,2-diazaphospholidine Iodine. Phenylthio(triphenylstannyl)methyllithium. Sodium amalgam. Sodium sulfide. Tri-n-butyltin hydride. Triethyl orthoformate. 

Tris(trimethylsilyl)silyllithium, which is readily formed upon treatment of tetrakis(trimethylsilyl)silane with methyllithium or triphenylsilyllithium in ether-tetrahydrofuran (63), is useful as the reagent for construction of molecules of an interesting class of highly sterically hindered methyl-polysilanes. The synthesis of hexakis(trimethylsilyl)disilane gives an example (59). 

In agreement with this hypothesis, tetrakis(trimethylsilyl)silane gives tris-(trimethylsilyl)silyllithium when treated with methyllithium or triphenyl-silyllithium in tetrahydrofuran (63). 

Reaction between tris(dimethylsilanyl)methyllithium and SiCh in toluene at room temperature resulted in multiple products, including highly substituted 1,3-disilacyclobutane (Equation 36) <1999OM1804>. 

A variety of new methods for the selective reduction of pyridine Ar-oxides to the corresponding pyridine have been developed. A procedure that is limited to the reduction of relatively electron-rich pyridine Ar-oxides utilizes hexamethyldisilane in the presence of methyllithium in THF/HMPA <1999JOC2211>. This reduction can also be performed on quinoline and isoquinoline Ar-oxides. Tris(2-carboxyethyl)phosphine (TCEP) can be used to... 

---