Lithium tetramethylpiperidine

Qudguiner s group lithiated a sym-disubstituted pyrazine, 2,6-dimethoxypyrazine (43), with lithium 2,2,6,6-tetramethylpiperidine (LTMP). The resulting lithiated intermediate was quenched with h to give 3-iodo-2,6-dimethoxypyrazine (44) and 3,5-diiodo-2,6-dimethoxypyrazine (45) [35]. Iodide 44 was then coupled with phenylacetylene to provide adduct 46. 

GABA HMG-CoA HMPA HT LDA LHMDS LTMP NADH NBH NBS NCS NIS NK NMP PMB PPA RaNi Red-Al RNA SEM SnAt TBAF TBDMS TBS Tf TFA TFP THF TIPS TMEDA TMG TMP TMS Tol-BINAP TTF y-aminobutyric acid hydroxymethylglutaryl coenzyme A hexamethylphosphoric triamide hydroxytryptamine (serotonin) lithium diisopropylamide lithium hexamethyldisilazane lithium 2,2,6,6-tetramethylpiperidine reduced nicotinamide adenine dinucleotide l,3-dibromo-5,5-dimethylhydantoin A-bromosuccinimide A-chlorosuccinimide A-iodosuccinimide neurokinin 1 -methyl-2-pyrrolidinone para-methoxybenzyl polyphosphoric acid Raney Nickel sodium bis(2-methoxyethoxy)aluminum hydride ribonucleic acid 2-(trimethylsilyl)ethoxymethyl nucleophilic substitution on an aromatic ring tetrabutylammonium fluoride tert-butyldimcthyisilyl fert-butyldimethylsilyl trifluoromethanesulfonyl (triflyl) trifluoroacetic acid tri-o-furylphosphine tetrahydrofuran triisopropylsilyl A, N,N ,N -tetramethy lethylenediamine tetramethyl guanidine tetramethylpiperidine trimethylsilyl 2,2 -bis(di-p-tolylphosphino)-l,r-binaphthyl tetrathiafulvalene... 

The major and recently used preparative routes to azidopyrazines have been covered already by azidolysis of halogenopyrazines (Sections 4.2.6 and 4.4) and by treatment of hydrazinopyrazines with nitrous acid (Section 7.4). In addition, direct C-azidation of pyrazines has been used for example, the lithio intermediate (225), generated in THF by treatment of 2-methoxypyrazine (224) with lithium 2,2,6,6-tetramethylpiperidine, gave 2-azido-3-methoxypyrazine (226) (87%) on subsequent treatment with p-toluenesulfonyl azide.232... 

Rathice and Kow first reported the preparation of a boron-stabilized carbanion by direct deprotonation of the carbon acid. They made the important observation that the deprotonation needed a sterically demanding base to prevent its complexation with boron. Thus the anion of B-methyl-9-borabicy-clo[3.3.1]nonane, prepared by deprotonation with lithium 2,2,6,6-tetramethylpiperidine (LiTMP) in benzene, can be alkylated successfully. 

Regioselective metalation of a wide variety of trifluoromethylated pyridines and quinolines was exhaustively studied by the Schlosser research group." " It was demonstrated that regioselectivity of direct lithiation of fluorinated heterocycles depends signihcantly on reagents, reaction conditions and type of solvent. For example, the lithiation of 2-CF3-pyridine using lithium 2,2,6,6-tetramethylpiperidine (LiTMP) in THF at —75°C results in exclusive formation of acid 109, while the reaction with BuLi in the presence of Et2NCH2CH20Li in less polar ether leads to selective formation of isomeric acid 110 (Fig. 7.39). ... 

The selection of the lithiation reagent also has a strong influence over the regioselectivity of the electrophilic substitution the bulkier the base, the more favorable the reaction at the C5 position. For example, lithium 2,2,6,6-tetramethylpiperidine (LiTMP) directs the formation of the C5-substituted product at a 79 1 ratio to the C2-substituted thiophene. A variety of electrophiles can be substituted after lithiation by LiTMP. ... 

H(f-C4H9)B-NC9Hi8 is a possible product of the reaction of (f-C4H9)2BCl and lithium-2,2,6,6-tetramethylpiperidine [15]. 

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