Halo ketimines

Formation of Cyclopropylideneamines by Favorskii-type 1,3-Dehydrohalogenation of cr-Halo Ketimines... 

Tertiary a-halo ketimines 3 reacted with alcohols in the presence of nitrogen bases, e.g. triethylamine, 1,4-diazabicyclo[2.2.2]octane, l,5-diazabicyclo[4.3.0]non-5-ene or 1,8-diaza-bicyclo[5.4.0]undec-7-ene, to afford mainly l-alkoxy-2,2-dialkylcyclopropylamines 4, together with variable amounts of a-alkoxy ketimines 5 and rearranged a-amino acetals 6. The geminal functionalized cyclopropanes 4, obtained in up to 80% yield, and the a-alkoxy ketimines 5, were formed via intermediate 2-(alkylamino)allylcarbenium ions 7. 

Table 1. l-Alkoxy-2,2-dialkylcyclopropylamines by Treatment of a-Halo Ketimines with Alcohols in the Presence of Base... 

It should be stressed that several cyclopropylideneamines 28 have been generated in situ from a-haloimines 3 under basic Favorskii conditions and that nucleophilic addition of the bases used (e.g. alkoxides, hydroxide) led to adducts 29 which, in most cases, were not isolable. Instead, they readily open to give the most stable carbanions (30 or 31). This feature accounts for the formation of branched amides 33 from aliphatic a-halo ketimines and of linear imidates 32 (Nu = OR) or amides 32 (Nu = OH) from a-chloro-a-phenyl ketimines. ... 

Secondary a-halo-ketimines are converted into a-alkylamino-acetals by reaction with anhydrous alcohols in the presence of a tertiary amine base [equation (40)]. Should the a-(alkylamino)carbonyl compound be required. 

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