New Applications of the Mannich Reaction
French chemists found that the reaction of trifluoroacetic anhydride with the N-oxide of trimethlyamine leads to the methylenedimethylimmonium trifluoroacetate. This salt is considered to be the actual reagent in the Mannich reaction conducted with dimethylamine and formaldehyde. Indeed use of this...
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| Format: | Others |
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TopSCHOLAR®
1976
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| Online Access: | https://digitalcommons.wku.edu/theses/2938 https://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=3946&context=theses |
| Summary: | French chemists found that the reaction of trifluoroacetic anhydride with the N-oxide of trimethlyamine leads to the methylenedimethylimmonium trifluoroacetate. This salt is considered to be the actual reagent in the Mannich reaction conducted with dimethylamine and formaldehyde. Indeed use of this salt gives higher yields than those obtained via the classical Mannich procedure. This salt could be distilled under vacuum (5 x 10-2 mm) and reacted with phenylmagnesium bromide to give an 80% yield of benzyldimethylamine. The trimethlsilyl ethers of ketones were employed as intermediates and exhibited regioselectively. For unsymmetrical ketones, the more stable enol was formed thermodynamically and the less hindered enolate was produced kinetically. The silyl ether isomers were followed by quenching with immonium salt and resulted in the regiospecific products of Mannich base. For α, β-unsaturated ketones, the enolate was formed in high yield by 1,4-addition when lithium dimethylcuprate was employed. ϒ-Butyrolactone could be alkylated, providing an intermediate to the construction of an α-methylene lactone, a moiety present in several compound having appreciable anti-tumor activity. |
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