Tetramethyl ethylenediamine TMEDA

In 1985, Kwiatkowski et al. reported a tetramethyl ethylenediamine (TMEDA)-catalyzed dimerization of ketene giving the interesting compound 4-methylene-oxetane-2-one (diketene). This substance can be hydrogenated by either Pd/C to racemic p-BL as well as by asymmetric catalysis according to Takaya et al. using Ru complexes of (5)-BINAP as catalyst, with an ee of 92% [111] (Fig. 39). 

The deuteriated (97%) imines 363 and 365, and the hydrazone 364 have been prepared396-399 by treating 2,6,6-trideuterio-2-methylcyclohexanone and 2,2,6,6-tetradeuteriocyclohexanone with the corresponding deuteriated ammonium salts (RND3CI) and used in the KIE studies of the metalation of the above C=N compounds with lithium diisopropylamide (LDA) in THF, in N, N, N A -tetramethyl ethylenediamine (TMEDA) and in dimethylethylamine (DMEA) solvents (equation 200). The rates, d[imine]/dt of that of imines 363 and 364 metalation are zero order with respect to [THF], [TMEDA]... 

Polymeric supports can also be used with advantage to form monofunctional moieties from difunctional (Hies. Leznoff has used this principal in the synthesis of sex attractants on polymer supports (67). Starting from a sheap symmetrical diol he blocked one hydroxyl group by the polymer. Functionalization of cross-linked polymers is mostly performed by chloromethylation (65). A very promising method to introduce functional groups into crosslinked styrene-divinylbenzene copolymers is the direct lithiation with butyllithium in presence of N,N,N, N -tetramethyl-ethylenediamine (TMEDA) (69, 70). Metalation of linear polystyrene with butyl-lithium/TMEDA showed no exchange of benzylic hydrogen and a ratio of attack at m/p-position of 2 1 (71). In the model reaction of cumene with amylsodium, a kinetic control of the reaction path is established. After 3h of treatment with amyl-sodiuni, cumene is metalated 42% in a-, 39% m-, and 19% p-position. After 20h the mixture equilibrates to affort 100% of the thermodynamically more stable a-prod-uct (72). 

The lithiation of poly(styrene-DVB) can be carried out according to two reaction routes. The first involves the transformation of -Br groups into -Li groups by reaction of a brominated polystyrene with an excess of n-butyllithium (15,16). The second involves the direct lithiation of poly(styrene-DVB) by reacting the resin with n-butyllithium and N,N,N, N -tetramethyl-ethylenediamine (TMEDA)(15,17). 

Form Supplied in commercially available as an approximately 1.7 M solution in pentane or heptane. Tetrameric in hydrocarbons, dimeric in diethyl ether, monomeric in THF although earlier reported as dimeric. In combination with tertiary polyamines such as N,N,N, N -tetramethyl-ethylenediamine (TMEDA), l,4-diazabicyclo[2.2.2]octane (DtYBCO), or N,N,N, N",N"-pentamethyldiethylenetriamine (PMDTA), reactivity is often increased. ... 

The influence of two tertiary polyamines on the a-nionic polymerization of isoprene in cyclohexane has been studied. TMEDA (N,N,N, N -tetramethyl-ethylenediamine) and PMDT (pentamethyIdiethylene-triamine) can increase or decrease the propagation rate, depending on the concentration range. The results are discussed on the basis of the nature of the living species. 

HydrocarbylComplexes. Stable homoleptic and heteroleptic thorium hydrocarbyl complexes have been synthesized. Two common homoleptic species are [Li-TMEDA], [Th(CH3)7] [92366-18-2] (19), where TMEDA = tetramethyl ethylenediamine, and Th(CH2C6HB)4 [54008-63-8] (20). 

Scheme 4. Takai-Lombardo reagents TMEDA= N.iV,Af, N -tetramethyl-ethylenediamine.

HMPA hexamethylphosphoramide. DMPU MA[ -dimethylpropyleneurea. TMEDA tetramethyl-ethylenediamine. Both are additives that coordinate metals and may inhibit aggregation. Note that mechanistic interpretation of the effect of additives, especially TMEDA in THF solvent, are risky... 

Cu(OCH3)C1 1.10 mol/1, pCO 0.8 MPa, T 25°C py= pyridine, DMPY=2,6 dimethylpyridine, TMEDA=tetramethyl -ethylenediamine, TEED A = tetraethylethylenediamine, TMMDA = tetramethyldiaminomethane, TMPDA=tetramethyl-l,3-diaminopropane, BIPY = 2,2 bipyridyl, TEA = triethylamine. 

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