2-Aza-allyl anions

Arrhenius parameters3 for thermal relaxation of conformation from cis,trans to trans,trans 1,3 diphenyl-2-aza-allyl anion... 

In the catalytic presence of tetrabutylammonium fluoride, a trimethylsilyl group is cleaved from AKtrimethylsilyl)rnethylbenzylimine to form the resonance-stabilized 2-aza-allyl anion which undergoes a Michael addition reaction with, for example, methyl acrylate, giving y-aminoesters.333 These types of aminoesters serve as a starting material for the elaboration of diversely substituted pyrrolidones.334... 

Several examples have appeared in the literature in which this linker has been employed in combinatorial chemistry strategies. Thus, it has been used in a Pd-mediated three-component coupling strategy for the solid-phase synthesis of tropane derivatives [46], in the solid-phase synthesis of aspartic acid protease inhibitors [47], in the attachment of cholic acid as a template for a combinatorial approach [48] and, more recently, in the solid-phase synthesis of pyrrolidines via 2-aza allyl anion cycloadditions with alkenes [49]. 

Intramolecular 2-aza-allyl anion cycloaddition was employed for the synthesis of the crinine-type alkaloids ( )-crinine (135) 142a) and (-)-amabiline (145) 142c) and has been reported to provide potential precursors of 6a-epi-pretazettine (314) and 6a-ep/-precriwelline (methoxy epimer of 314) 142b). 

A-Chloroamines (e.g. 14), on treatment with strong bases such as potassium Fbutoxide or lithium diisopropylamide (LDA), give 2-aza-allyl anions (15) that can undergo r4s -I- tt2s cycloadditions with alkenes to give pyrrolidines. Imines can also be accessed by dehydrochlorination of (14), under modified conditions. ... 

Azabuta-l,3-dienes have been prepared in which the imino group is conjugated with an enol ester acylation of carbanions derived from N-(diphenylmethyl)arylmethanimines affords a wide range of the 2-azadienes (Scheme 197). The site selectivity for the attack of the electrophile on the aza-allyl anion depends upon the substituents on the carbanion, and on the hardness of the... 

To a solution of lithium diisopropylamide (LDA, 0.105-0.150 mol) at 0°C in 150 mL THF (prepared from 0.105-0.150 mol n-BuLi and 0.2 mol diisopropylamine) was added a solution of 0.1 mol a-chloro ketimine in 20 mL THF. The deprotonation was complete after 2 h at 0°C, then 0.1-0.2 mol acetone was added dropwise to the solution of 3-chloro-1-aza-allylic anion. After the addition, the reaction mixture was stirred for 10 h at room temperature. The reaction mixture was then poured into water and extracted with ether (3 X100 mL). The combined extracts were dried over MgS04, and the solvent was removed under reduced pressure. The product was purified via vacuum distillation between 50°C and 60°C at 13 mmHg. 

Organomagnesium compounds react with imines, prepared from 3-methoxy-2-naphth-aldehydes by a 1.4-addition mechanism. This reaction can be performed with high diastere-oselectivity. The method was applied for the synthesis of optically pure S-tetralones . Vinyhnagnesium bromide reacts as an acceptor with a ketone dimethyl hydrazone zincate 207, yielding a 1,1-bimetallic species, which can be reacted sequentially with two different electrophiles (equations 131 and 132) . The reaction proceeds via a metalla-aza-Claisen rearrangement, where the dimethylhydrazone anion behaves as an aza-allylic system . 

Sigmatropic rearrangements of anions of (V-allyl amines have also been observed and are known as aza-Wittig rearrangements.291 The reaction requires anion stabilizing substituents and is favored by (V-benzyl and by silyl or sulfenyl substituents... 

Aza-Wittig rearrangement in the acyclic series are harder to control.141 The most reliable turn out to be those of allyl amides such as 192 in which the allyl group bears a (3-silyl substituent, whose function is to stabilise the anionic transition state of the reaction.142 143... 

Sigmatropic Rearrangements of Anions of Allyl Ethers The Wittig and Aza-WUtig Rearrangements... 

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