Takudrei

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Vinylogous Aza-Enamines as Neutral d3 Nucleophiles: Aminomethylations of N,N-Dimethylhydrazones of alpha,beta-Unsaturated Aldehydes

M. T. Grabowski, K. Nowosinski, D. Lentz, R. Brehme, C. A. Schalley— 2010

N,N-Dimethylhydrazones of propenal- and 2-methyl­propenal and their derivatives and homologues (vinylogous aza-enamines) were allowed to react with N,N-dimethylformiminium chloride in moisture-free dimethylformamide to yield singly, doubly, and even triply aminomethylated products. They can be easily separated and characterized as crystalline hydrochlorides. The reaction takes place at the ω-position of the π-system. This is a consequence of the conjugative interaction of the electron-donating aminohydrazone group with the double bond system in analogy to the enamines. The formation of dialkylhydrazones from unsaturated aldehydes thus causes the umpolung of the formerly electrophilic d³-building blocks into a nucleophile. Depending on the reaction conditions and confirmed by crystal structures and 2D NMR experiments, control can be exerted over the degree of substitution: Up to trisubstituted products were obtained for the 2-methylpropenal derivative. The hydrochlorides can be easily deprotonated to yield the free aminohydrazone bases. The back-conversion of the aminohydrazones into the corresponding amino aldehydes is possible under acidic conditions.

Title147
Vinylogous Aza-Enamines as Neutral d3 Nucleophiles: Aminomethylations of N,N-Dimethylhydrazones of alpha,beta-Unsaturated Aldehydes
AuthorM. T. Grabowski, K. Nowosinski, D. Lentz, R. Brehme, C. A. Schalley
Date20100809
IdentifierDOI 10.1055/s-0030-1258194
Source(s)
CitationSynthesis 2010, 3556-3568