Lithium tetramethyldiphenyldisilylamide

Deprotonation of carbonyl compounds by lithium dialkylamide bases is the single most common method of forming alkali enolates. Four excellent reviews have already been published. " Sterically hindered amide bases are employed to retard nucleophilic attack on the carbonyl group. The most common and generally useful bases are (i) lithium diisopropylamide (LDA 5) (ii) lithium isopropylcyclo-hexylamide (LICA 6) (iii) lithium 2,2,6,6-tetramethylpiperidide (LITMP 7) (iv) lithium hexamethyldisilylamide (LHMDS 8) and (v) lithium tetramethyldiphenyldisilylamide (LTDDS 9). Bases that are not amides include sodium hydride, potassium hydride and triphenylmethyllithium. 

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