Allenes dilithiated

Reaction of Me3GeCl with a substituted cyclopropene in the presence of lithium diisopropylamide (LDA) yields different products depending on the order of addition of the reagents.97 Addition of LDA to a mixture of the reactants gives the dimetallated cyclopropene (Equation (76)). Dilithiation of the cyclopropane followed by addition of Me3GeCl gives the allene (Equation (77)). 

A domino reaction, whereby up to four equivalents of a nitrile can be added to dilithiated allenes, is believed to proceed via a novel rearrangement. ... 

Propargyl dianion (QF I ). This anion can be prepared by dilithiation of allene with BuLi in 1 1 ether/hexane. Use of THF (- 50°) or BuLi/TMEDA results in a mixture of propargylide and allenyl anions. The anion couples readily with alkyl and allyl halides to give terminal alkynes. The intermediate lithium acetylide can also react with various electrophiles.3 Example ... 

Heating the diselenoallene 140 leads to an intramolecular cycloaddition affording the fused selenin 141 (Scheme 15) <2001JOG1787>. The reaction appears to take place by an initial intramolecular hydrogen abstraction by the sp-hybridized carbon of the allene affording a diradical intermediate. Radical coupling then leads to the selenin. The cyclic allene precursor could be prepared by dilithiation of the benzylacetylene followed by treatment of the bis-selenocyanate. 

Dilithiation of allene leads to the acetylene LiCH2C=CLi. Alkyl-substituted allenes also react, e.g. ... 

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