Bases Butyllithium-Tetramethylethylenediamine

Simple benzamides undergo slow deprotonation with amide bases. Stronger base systems such as. r-butyllithium in tetramethylethylenediamine (TMEDA) are too nucleophilic for sinqrle benzamides but /V,N-dimethyl-2,4,6-triisopropylbenzamide is deprotonated in only 5 min at -78 C, and this anion is alkylated with methyl iodide to give a 77% yield of Ae expected product. ... 

A more versatile approach to 4,7-disubstituted dihydroacepentalenes 65 is via the stable acepentalene dianion 64 as an easily accessible intermediate. Dipotassium acepentalenediide 64 can be obtained in virtually quantitative yield by treatment of triquinacene 10 with the superbasic mixture of potassium f-pent-oxide and butyllithium [or even better potassium f-butoxide, butyllithium and tetramethylethylenediamine (TMEDA)] in hexane, the so-called Lochmann-Schlosser base (Scheme 15) [62, 63]. Mechanistically this transformation has... 

The allylic anions are normally generated by deprotonation of the corresponding allylic derivatives with -butyl- or. r-butyl-lithium, often in conjunction with NjVjV X-tetramethylethylenediamine (TMEDA) or hexamethylphosphoramide (HMPA). Lithium dialkylamides are also employed. The deprotonation is usually petfonned in THF or ether at -65 C or lower because of the high reactivity of both the lithium bases and the resulting allylic anions. Chloro-substituted allylic anions are most efficiently prepared by transmetallation of 3-chloroallyltriphenyllead with n-butyllithium. 

Rather than blending for example an SBR and a polybutadiene or polyisoprene, copolymers or terpolymers based on styrene and butadiene, butadiene and isoprene, styrene and isoprene, or styrene, butadiene, and isoprene can be prepared having a dual Tg. Using n-butyllithium catalyst and h/, h/, N, N -tetramethylethylenediamine (TMEDA) as a modifier, a range of polymer dual glass transition temperatures can be obtained (Table 4.6). 

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