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LiCH3 and LiCH2CH3 react with the complex [Mo2(H)2(μ‐AdDipp2)2(thf)2] (1⋅thf) with coordination of two molecules of LiCH2R (R=H, CH3) and formation of complexes [Mo2{μ‐HLi(thf)CH2R}2(AdDipp2)2], 5⋅LiCH3 and 5⋅LiCH2CH3, respectively (AdDipp2=HC(NDipp)2; Dipp=2,6‐iPr2C6H3; thf=C4H8O). Due to steric hindrance, only one molecule of LiC6H5 adds to 1⋅thf generating the complex [Mo2(H){μ‐HLi(thf)C6H5}(μ‐AdDipp2)2], (4⋅LiC6H5). Computational studies disclose the existence of five‐center six‐electron bonding within the H−Mo≣Mo−C−Li metallacycles, with a mostly covalent H−Mo≣Mo−C group and predominantly ionic Li−C and Li−H interactions. However, the latter bonds exhibit non‐negligible covalency, as indicated by X‐ray, computational data and the large one‐bond 6,7Li,1H and 6,7Li,13C NMR coupling constants found for the three‐atom H−Li−C chains. By contrast, the phenyl group in 4⋅LiC6H5 coordinates in an η2 fashion to the lithium atom through the ipso and one of the ortho carbon atoms. [ABSTRACT FROM AUTHOR]

The reaction of MeLi with several group 6 phosphine end‐on dinitrogen complexes of the general formula [ML4(N2)2] (M = Mo or W) is reported. Unlike the isoelectronic complex [CpMn(CO)2(N2)] on which RLi reagents have been reported to add to the N2 ligand, we show herein that MeLi attacks the metal centre to afford rare anionic trans methyl dinitrogen complexes. [ABSTRACT FROM AUTHOR]

The title compound (1) was chosen as a model for the α/α′‐regioselectivity of deprotonation and subsequent alkylation adjacent to the C=N bond. With the bulky base lithium N,N‐diisopropylamide (LDA) as a catalyst, the one‐pot deprotonation steps can be performed through titration with methyllithium, using gas‐volumetric observation of the liberated methane. In the first step with ensuing methylation by iodomethane, the primary product is born at −40 °C in its metastable (Z) configuration (kinetic control) and may be either isolated or converted in situ at 30 °C into its thermodynamically favored (E)‐isomer via cis to trans stereoinversion at the N‐atom. Being slow enough on the laboratory time scale, this stereoinversion process can serve to control the regioselectivity of the second deprotonation/alkylation sequence as follows. The α,α′‐products are formed from the intermediate (Z)‐imine, whereas α,α‐products result from the intermediate (E)‐imine; in either case, syn deprotonation (cis to tBu at nitrogen) by LDA is apparently disfavored by the tBu group, so that anti deprotonation becomes obligatory. If a third one‐pot deprotonation step is too slow with LDA, it may be performed with the stronger base butyllithium/HMPA which, however, reacts regio‐unselectively. Regioselective one‐pot, LDA‐catalyzed deprotonation with alkylation by oxiranes (alone, or alternatingly with iodomethane) opens a short access to spiro‐[2.4]heptan‐4‐ones. [ABSTRACT FROM AUTHOR]

The study introduces different organosilicon derivatives incorporating sulfanyltetrazole ring for biological applications. Initially, the sulfanyltetrazole derivatives and halo-analogues (Br, I) were synthesized. Later, selective reaction of tris(trimethylsilyl)methyllithium (TsiLi) in the presence (−46 and 0 °C) and absence (room temperature) of CS2 with halo-sulfanyltetrazole derivatives yielded new multifunctional sulfanyltetrazole regioisomers with SH, C = S, ethynylthio and SiMe3 groups, respectively. All the synthesized compounds were characterized by IR, 1H-NMR, 13C-NMR spectra and elemental analysis data. The compounds were screened for their antibacterial activities against clinically important gram-positive and gram-negative bacteria using the spectrophotometric microdilution method. The preliminary screening indicated that the organosilicon derivatives incorporating SH and C = S (mercapto-silyl-thiones) and silyl-thioalkynes have antibacterial activities, whereas no antibacterial activity was observed on compounds containing (Me3Si)3C groups. Of the synthesized compounds, compound 5d showed the best activity against all the tested organisms (3.91-31.25 µg/mL). [ABSTRACT FROM AUTHOR]

The salt metathesis reaction between homoleptic calcium bis(trimethylsilyl)amide [Ca{N(SiMe3)2}2]2 and "halide-free" methyllithium allowed for the isolation of X-rayamorphous dimethylcalcium [CaMe2]n in good yields and purities. The formation of [CaMe2]n was proven by microanalysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe2]n could be crystallized from chilled thf solutions as the heptametallic adduct [(thf)10Ca7Me14]. Reaction of [CaMe2]n with CaI2 in thf led to the dimeric complex [(thf)3Ca(Me)(I)]2, whereas in tetrahydropyran (thp) the trinuclear complex [(thp)5Ca3(Me)5(I)] was obtained, both representing the first crystallographically characterized heavy-Grignard compounds with methyl groups as the hydrocarbyl ligand. While protonolysis of [CaMe2]n with the superbulky proligand HTptBu,Me in nonpolar solvents gave homoleptic (TptBu,Me)2Ca, reaction in donor solvents (thf, thp) afforded the monomeric complexes [(TptBu,Me)Ca(Me)(thf)] and [(TptBu,Me)Ca(Me)(thp)], which are the first examples bearing terminal Ca-CH3 functionalities. Grignard-type nucleophilic methyl-group transfer to hexamethylacetone gave access to the dimeric alkoxide complexes [(thf)Ca(OCtBu2Me)2]2 and [(tBu2CO)Ca(μ2-OCtBu2Me)3 -Ca(OCtBu2Me)]. Finally, addition of the Lewis acid GaMe3 to [CaMe2]n led to the corresponding tetramethylgallate compound [Ca(GaMe4)2]n. [ABSTRACT FROM AUTHOR]

Improvement of synthesis of non-peripherally alkyl-substituted macrocycle molecules, 1,4,8,11,15,18,22,25-octaalkyltetrabenzotriazaporphyrins (CnTBTAPH2) has been investigated. In the reaction from 3,6-dialkyl phthalonitrile to CnTBTAPH2, the yield has been markedly improved by replacing a conventional Grignard reagent with methyllithium. The modified procedure using a stable solvent was significantly effective for the scale-up of the reaction system as well as the yield enhancement. [ABSTRACT FROM AUTHOR]

A simple and robust procedure for the synthesis and use of thermally unstable dichloromethyllithium in continuous flow mode is described. By utilizing residence times in the range of milliseconds for the generation and electrophilic quench of dichloromethyllithium, the straightforward synthesis of dichlorocarbinols and benzylic pinacol esters was realized at reaction temperatures of -30 °C, whereas typical temperatures in traditional batch mode are below -78 °C. The excellent purity profile obtained from the flow process allows us to directly telescope the exiting flow stream into semibatch quenches for further modifications. All transformations gave the desired products in remarkable purity and yield on gram scale with no need for chromatography. [ABSTRACT FROM AUTHOR]

The formation of 1,3-diketones was observed in the reactions of bulky acyl chlorides with methyllithium. The reaction products depend on the steric hindrance around the carbonyl group of the acyl chloride and the electronic effect of the group(s) linked to the carbonyl. When the steric hindrance around the carbonyl group of the acyl chloride is big enough, the 1,3-diketone is the only product. In the case of the moderate hindrance around the carbonyl group of the acyl chloride, a moderate yield of 1,3-diketone is obtained and some tertiary alcohol is generated. When there is no steric hindrance around the carbonyl group of the acyl chloride, the tertiary alcohol is the only product. When the steric hindrance around the carbonyl group is moderate and an electron-donating group is connected to the carbonyl of the acyl chloride, all three products—ketone, 1,3-diketone and tertiary alcohol—can be isolated from the reaction mixture after long reaction times.

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol-1 and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150% enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. [ABSTRACT FROM AUTHOR]

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol−1 and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. [ABSTRACT FROM AUTHOR]

Herein we report an efficient catalytic system for the titanium-promoted enantioselective addition of organolithium reagents to aldehydes, based on chiral Ar-BINMOL ligands. Unprecedented yields and enantioselectivities are achieved in the alkylation reactions of aliphatic aldehydes. Remarkably, methyllithium can be added to a wide variety of aromatic and aliphatic aldehydes, providing versatile chiral methyl carbinol units in a simple one-pot procedure under mild conditions and in very short reaction times. [ABSTRACT FROM AUTHOR]

An efficient, chemoselective approach to spiro-epoxyoxindoles via the addition of chloromethyllithium followed by ring-closure of the intermediate alkoxide is reported. Chemoselectivity is fully preserved in the presence of different electrophilic sites. The synthetic potential of selected spiro-epoxyindoles has been exploited in the copper(I)-catalyzed intramolecular oxyarylation of an alkyne and in the formation of N,N-dimethylisoindigo via the addition of dihalocarbenoids. [ABSTRACT FROM AUTHOR]

Three unexpected products derived from the unsymmetrically substituted amidinate anion [MeC(NEt)(N t Bu)] − are reported. Treatment of 1- tert -butyl-3-ethyl-carbodiimide, t Bu-N C N–Et, with 1 equiv. of methyllithium in diethyl ether afforded colorless crystals of the unusual octanuclear lithium amidinate derivative {[LiN(Et)C(Me)N( t Bu)] 2 ⋅ LiN(Et)C(CH 2 Li)N( t Bu) Et 2 O} 2 ( 1 ) in 57% yield instead of the expected lithium amidinate Li[MeC(NEt)(N t Bu)]. In the molecule of 1 , one central methyl group in a trimer of Li[MeC(NEt)(N t Bu)] is deprotoned and two of these partially deprotonated trimers are linked through a central eight-membered [C–N–Li–CH 2 ] 2 ring to afford the octanuclear product 1 . The same reaction carried out in 1,2-dimethoxyethane (DME) solution produced the oxygen-centered, heptanuclear lithium amidinate cluster {Li[MeC(NEt)(N t Bu)]} 5 ⋅ Li 2 O ( 2 ) (21% yield). Treatment of anhydrous praseodymium trichloride with in situ -prepared Li[MeC(NEt)(N t Bu)] in Et 2 O/THF afforded green (THF)Li[Pr{MeC(NEt)(N t Bu)} 4 ] ( 3 ) as the first anionic tetrakis(amidinato)lanthanide(III) complex in 55% isolated yield. The molecular and crystal structures of all three new compounds have been elucidated by X-ray diffraction. [ABSTRACT FROM AUTHOR]

α-Iodoaziridines are unusual motifs and intriguing structures for further functionalisation of the intact aziridine. The preparation of N -protected α-iodoaziridines is achieved through an addition-cyclisation reaction of LiCHI 2 with imines. The effects of varying the N -group and using different carbenoids are investigated. Excellent cis -stereochemistry is achieved, except for N -carbamates containing aryl groups. Using the mixed carbenoid LiCHICl, the iodide leaving group is selected for cyclisation affording chloroaziridines only, as a cis / trans mixture. More convenient and higher yielding conditions for the preparation of alkyl N -Ts α-iodoaziridines are developed, using ClMgCHI 2 . Additionally, the formation of the problematic primary alkyl α-iodoaziridines is achieved. [ABSTRACT FROM AUTHOR]

α, β-Unsaturated N-benzenesulfonyl imine 1 was treated with 1.1 eq methyllithium to afford 1,2-addition adduct as a sole product. However, when compound 1 was treated with 2 eq MeLi, 1,2-addition product, benzenesulfonamide derivative 3 and 2 H-1,2-benzothiazine 1,1-dioxide derivatives 4 and 5 were isolated. [ABSTRACT FROM AUTHOR]

The competition between basicity and nucleophilicity of two standard organolithium reagents was studied using DFT. Comparing the reactivity of solvated (MeLi)2 and (LDA)2 toward propanal finally explains why methyllithium adds onto the carbonyl while LDA deprotonates the α-position, in accord with experiment and Ireland's deprotonation TS. [ABSTRACT FROM AUTHOR]

The one-pot synthesis of tetrasubstituted imidazoles by use of a series of LaxSr1 − xFeyCo1 − yO3perovskites as catalysts is described. The La0.8Sr0.2Fe0.34Co0.66O3nanocatalyst had the greatest activity in the heterogeneous cyclocondensation of an aldehyde, benzil, ammonium acetate, and a primary aromatic amine in water under ultrasonic irradiation. Some of the derivatives generated during this work were utilized as substrates for the synthesis in good yields of novel multifunctional tetrasubstituted imidazoles with Me3Si, C=S, and SH groups, via nucleophilic attack of tris(trimethylsilyl)methyllithium (TsiLi) at the carbon of carbon disulphide. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed direct cross-coupling of a range of organic chlorides and bromides with the bifunctional C(sp ³)-(trimethylsilyl)methyllithium reagent is reported. The use of Pd-PEPPSI-IPent as the catalyst allows for the preparation of structurally diverse and synthetically versatile benzyl- and allylsilanes in high yields under mild conditions (room temperature) with short reaction times. [ABSTRACT FROM AUTHOR]

The aggregation state of the α-sulfinyl-functionalized methyllithium compound [Li 2 {CH 2 S(O)Ph} 2 (TMEDA) 2 ] ( 1 ) in solution and its carbenoid reactivity is presented. Temperature dependent NMR measurements of 1 in THF-d 8 revealed the presence of an intermolecular dynamic process (dimer–monomer–dimer equilibrium) with a Gibbs free energy of activation of about 45 kJ/mol. 1 H DOSY NMR measurements exhibited that in THF-d 8 solution the coligand TMEDA is partially cleaved off. Furthermore, the decomposition of 1 in THF-d 8 (room temperature, 96 h) led to the formation of ethylene and PhSSPh. In refluxing toluene 1 decomposed with formation of ethylene, PhSSPh, xylenes, ethylbenzene, n -propylbenzene and isopropylbenzene. The dimerizing α-elimination yielding ethylene and the C–H insertion reactions observed in boiling toluene give proof of a carbenoid reactivity of 1 . [ABSTRACT FROM AUTHOR]

Thioflavanones are prevalent heterocyclic structural units in pharmaceutical and biologically active compound (Scheme [ABSTRACT FROM AUTHOR]

Several highly modular chiral amino diol tridentate ligands were found to be effective for the asymmetric alkylation reaction of aromatic aldehydes in the presence of methyllithium reagent, providing up to 96% ee values and up to 94% yields under relatively mild conditions. The investigation of the catalytic activity of these ligands shows a correlation of enantioselectivities of ligands with steric properties of substituent N-alkyl and nucleophilic Li-alkyl. With the addition of Ti(O-i-Pr)4 to the ligand 3c, the ¹H NMR spectrum reveals a hexa-coordinate Ti transition state complex with only one Ti metal center generated in solution. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of tris(trimethylsilyl)methyllithium, (Me3Si)3CLi, and carbon disulfide with various epoxides have been studied. By an unusual rearrangement hydroxy-mercaptobis-(trimethylsilyl)-thiones have been synthesized in good yields. Unexpectedly, in the case of 2-phenyloxirane two structural isomers (2g) and (2h) have been formed which was confirmed by IR, 1H and 13C NMR spectroscopy. Moreover, the reaction of (PhMe2Si)3CLi and (Me3Si)3CLi with CS2 in the presence of epoxides has been compared. [Copyright &y& Elsevier]

A series of bis(benzylthio)- and bis(allylthio)-2,2-bis(dimethylphenylsilyl) ethenes has been obtained by the reaction of (PhMe2Si)3CLi and CS2with benzyl and allyl bromides. A plausible mechanism for the formation of these compounds has been proposed. The reactivity of (PhMe2Si)3CLi toward CS2has been compared with that of (Me3Si)3CLi. The reaction of (PhMe2Si)3CLi with CS2and 2-methyloxirane gave a cyclic thiocarbonate. [ABSTRACT FROM AUTHOR]

Enantiomerically pure fluoro-[D1]methyllithium and iodo-[D1]methyllithiums of up to 92 % ee were generated by transmetalation of the corresponding stannanes with MeLi in THF at various temperatures. The intermediate halo-[D1]methyllithiums were trapped with benzaldehyde or acetophenone already present in excess in the reaction mixture to either give halohydrins or to disintegrate to carbene. The fluoro-[D1]methyllithiums were found to be microscopically configurationally stable within the tested range of −95 to 0 °C, but chemically only stable at temperatures below −95 °C due to a rapidly increasing portion disintegrating to carbene. The iodo-[D1]methyllithiums were configurationally labile relative to the rate of addition to PhCHO at all temperatures tested (−95 to −30 °C). Disintegration to carbene interfered as well. [ABSTRACT FROM AUTHOR]

The asymmetric nucleophilic 1,2-addition of (S)-N-benzylidene-2-methylpropane-2-sulfinamide with methylmagnesium bromide and methyllithium has been investigated using DFT(B3LYP) computations. The calculated ratio of the two diastereomers agrees with experimental observations, and the factors that determine the diastereomeric ratio are discussed. The preference for the E isomer and the rapid equilibrium between the E and Z isomers of N-tert-butanesulfinyl imine are two key features for understanding the mechanism of this reaction. Methylmagnesium bromide and methyllithium have bifunctional roles, acting as both Lewis acid and nucleophile, and the Lewis acid character plays a determining role in the stereoselectivity of the reaction. [ABSTRACT FROM AUTHOR]

Tris(trimethylsilyl)methyllithium (TsiLi) reacts with CS2via cleavage of the C=S double bond and unexpected rearrangement to give sulfur-containing organosilicon compounds. The intermediate, from the reaction between TsiLi and CS2is not stable but it has been trapped by various alkyl halides to give mercaptobis-(trimethylsilyl)-thiones. These reactions are quantitative and high yields in short periods of time have been obtained. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of the bis-dibromocarbene adduct of cyclonona-1,4,7-triene with methyllithium leads to a mixture of meso and racemic cycloundeca-1,2,5,6,9-pentaenes; the former rearranges at ambient temperature through a set of pericyclic reactions. [Copyright &y& Elsevier]

The three-coordinate complex Me2Ga[B-(NArCH)2] (Ar = C6H3iPr2-2,6) is accessible via a tandem Lewis acid-base metathesis protocol employing (THF)2Li[B(NArCH)2] and GaMe3. It features a very short Ga-B bond of 2.067(3) A, which was further investigated by DFT calculations and the analysis of the electron density. Reaction of MeLi with Me2Ga[B- (NArCH)2] forms tetrameric [LiMe3Ga{B(NArCH)2}]4 with a "nanowheel" structure. [ABSTRACT FROM AUTHOR]