Lithiated methyl amines

Propargylic carbonates are converted to substituted allenyllithium species but I -alkynylsilanols undergo dilithiation (with r-BuLi-HMPA) and the subsequent reaction with electrophiles at the propargylic position. The doubly lithiated A-methyl aminals can be used in the preparation of Si-N- and P-N-containing heterocycles. ... 

Aromatic methyl amines, as the N,N-dimethyl derivatives, are readily lithiated at ortho positions Indeed the —CH NMe group is a very good lithiation directing group. On treatment of the lithio derivative with CICOOEt, introduction of COOEt group takes place ortho to —CH NMCj. The dimethyl amino group is also displaced by —Cl to give the chloro ester which on thermal cyclisation furnishes the phthalide. 

The Homer-Wadsworth-Emmons (HWE) reaction of a lithiated (diphenylphosphinoyl)methyl amine with a biaryl aldehyde furnishes the corresponding enecarbamates, which serve as key intermediates for the synthesis of the Amaryllidaceae alkaloid buflavine (eq 44). ... 

Poly(phenylene oxide)s undergo many substitution reactions (25). Reactions involving the aromatic rings and the methyl groups of DMPPO include bromination (26), displacement of the resultant bromine with phosphoms or amines (27), lithiation (28), and maleic anhydride grafting (29). Additional reactions at the open 3-position on the ring include nitration, alkylation (30), and amidation with isocyanates (31). 

Acyl hydrazides are useful precursors for the synthesis of 1,2,4-triazoles. Reaction of acyl hydrazides 149 with imidoylbenzotriazoles 148 in the presence of catalytic amounts of acetic acid under microwave irradiation afforded 3,4,5-trisubstituted triazoles 150 <06JOC9051>. Treatment of A-substituted acetamides with oxalyl chloride generated imidoyl chlorides, which reacted readily with aryl hydrazides to give 3-aryl-5-methyl-4-substituted[ 1,2,4]triazoles <06SC2217>. 5-Methyl triazoles could be further functionalized through a-lithiation and subsequent reaction with electrophiles. ( )-A -(Ethoxymethylene)hydrazinecarboxylic acid methyl ester 152 was applied to the one-pot synthesis of 4-substituted-2,4-dihydro-3//-1,2,4-triazolin-3-ones 153 from readily available primary alkyl and aryl amines 151 <06TL6743>. An efficient synthesis of substituted 1,2,4-triazoles involved condensation of benzoylhydrazides with thioamides under microwave irradiation <06JCR293>. 

By contrast, the lithiation of 479 with n-BuLi, which is assisted by coordination to the NMc2 group, is faster, reaching completion in less than 6 h at 25 °C, and completely regioselective ° °. The mesitylmethyl amine 480 is lithiated only at the methyl group ortho to the aminomethyl substituent (Scheme 189). 

N-Methylindole-2-carboxaldehyde also undergoes /8-lithiation, after in situ conversion to its a-amino alkoxide with lithium A-methylpiperazide, and the resulting 3-lithio species has been successfully alkylated with methyl iodide (Scheme 22)(87JOC104). However, when the same reaction was repeated using N,A(,A -trimethylethylenediamine as the amine com-... 

Titanium ylides are generated from imine esters with titanium isopropoxide chlorides and amines or by transmetalation of the N-lithiated ylides (90,91). The regioselectivity of their reactions with methyl acrylate is opposite to that normally observed (90). A transition state is proposed in Scheme 11.13 to explain this alternative regioselectivity. Intramolecular cycloadditions of the titanium ylides offer a synthetic application of this regioselectivity. 

Lithiation of 2-methyl-3,4-dihydronaphthalen-l(2//)-one followed by treatment with iY-fluorobis(phenylsulfonyl)amine (la) gives 2-fluoro-2-methyl-3,4-dihydronaphthalen-1(2//)-one in 50% yield.131... 

Lithiation of dibenzofuran with butyllithium and mercuration both occur at the 4-position. Thallation occurs at the 2-position, however (57IZV1391). The mercury and thallium derivatives serve as a source of the iodo compounds by reaction with iodine. Bromodibenzofurans undergo bromine/lithium exchange with butyllithium and the derived lithio compounds may be converted into phenols by reaction with molecular oxygen in the presence of a Grignard reagent, into amines by reaction with O-methylhydroxylamine, into sulfinic acids by reaction with sulfur dioxide, into carboxylic acids by reaction with carbon dioxide and into methyl derivatives by reaction with methyl sulfate (Scheme 100). This last reaction... 

The methodology to synthesize polymer hybrids by living anionic polymerization is shown in Fig. 3 [30]. Polyolefins containing p-tolyl groups have been used to initiate anionic polymerization by the lithiation of the methyl moiety using alkyl lithium and amine compounds system. 

Zirconocene methyl amide complexes 1 are readily prepared by addition of lithiated secondary or N-silyl amines to zirconocene methyl chloride [17] or zirconocene methyl triflate [18] (Eq. 1). Loss of methane from 1 yields zirconaaziridines which, in the presence of THF or PMe3, can be isolated as the adducts 2 in high yield and purity. This synthetic method is ideal when the isolation and characterization of the resulting zirconaaziridine is desired, as the C-H activation and concomitant methane evolution occur with the formation of little side product. 

---