Reaction with lithium amides

In contrast to the reaction with lithium amide, the sodium amide suspension immediately settles out after stopping the stirring and the supernatant ammonia has a grey or black colour, due to colloidal iron. In some cases it took a long time before all of the sodium had been converted (note 4). A further 0.1 g of iron(III) nitrate was then added to accelerate the reaction and some liquid ammonia was introduced to compensate for the losses due to evaporation. 

Apparatus 4-1 flask (see Fig. 2) for the reaction with lithium amide 3-1 silvered Dewar flask, provided with a rubber stopper and a gas outlet for the hydroxyalkylation (no stirring was applied). 

The chiral naphthyloxazoline substrates can also be employed in asymmetric carbon-heteroatom bond-forming reactions with lithium amides, which provide unusual... 

Due to the high interest in metalation reactions with lithium amide or alkyllithiums, an indicator scale of lithium ion pairs in THF has been developed119. Aggregation studies have indicated that organolithium species exist predominantly, if not exclusively, as monomers in the 10-3-10-4 M concentration range. Particular attention has been devoted to the lithium and caesium ion-pair acidities of diphenylamine in THF120 that, at 25 °C, have been found to be 19.05 and 24.20, respectively. 

Asami and coworkers also investigated the deprotonation of cyclooctene oxide 97, which is known to undergo both a-deprotonation to yield transannular products and / -deprotonation to yield allylic alcohols 98 upon reaction with lithium amides. Using his catalytic system Asami and coworkers obtained the allylic alcohol in 27% yield and 54% ee of (,S )-98 (Scheme 68c). (Z)-4-Octene oxide 99 was deprotonated yielding the allylic alcohol 100 in 54% yield and 60% ee of the (5)-enantiomer (Scheme 68d)110. 

The best yield (99%) was obtained with DATMP in benzene or hexane. Under similar conditions 98 is transformed into 99 in good yield (Eq. 117), in contrast to reaction with lithium amide where the yield is only 5%. 

In the procedure described in this experiment, o- and p-tolunitrile are metallated with alkali amides in liquid ammonia and with KDA in THF and the intermediary anions alkylated with butyl bromide. Side-reactions such as selfcondensation or addition of the base across the C=N function only take place during the reactions with lithium amide, but to a lesser extent than with LDA in THF. 

Trifluoroacetylindoles are useful stable equivalents of acid chlorides, giving amides or acids in haloform reactions with lithium amides or aqueous base respectively. The reactivity of the A -hydrogen compounds is greater than of those with A -alkyl, indicating the intermediacy of a ketene in the reactions of the former. ... 

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