Reductive amination of 1,4-diketones

Many synthetic methods have been reported for the pyrrolidine alkaloids, including procedures based on the Hofmann-Loffler reaction 132,412), the metal hydride reduction of pyrrolines 413,414), the a-alkylation of N-nitro-sopyrrolidine 412,415), the catalytic hydrogenation of pyrroles 133), the reductive amination of 1,4-diketones 25,138), the direct alkylation of 1-methoxy-carbonyl-3-pyrroline 416), the versatile synthesis from the Lukes-Sorm dilac-... 

Catalytic hydrogenation of the unstable pyrroles (281a-c), which are prepared by heating the 1,4-diketones (280a-c) with an excess of ammonium carbonate at 120°C, gives 2,5-dialkylpyrrolidines (lOa-c) (cis trans = 85 15, 85% conversion) (Scheme 25) 133). Reductive amination of 1,4-diketones (282b,f,h,i) with ammonium acetate and sodium cyanoborohydride produces 2,5-dialkylpyr-rolidines (10b,f,h,i) identical to natural products in 50-90% yields. Each pyrrolidine is an approximately 1 1 mixture of cis and trans isomers (Scheme 26) 25,138). 

Dialkylpyrrolidines. These compounds can be prepared by reductive amination of 1,4-diketones with sodium cyanoborohydride and ammonium acetate (4, 448-449). 1-Pyrrolines are usually formed also, but they can be reduced to pyrrolidines by NaBH4 in a second step.1... 

The principal component of the secretion of the poison gland of the European thief ant (Solenopsis fugax) is rrarcs-2-n-butyl-5-n-heptylpyrrolidine, identified by mass spectrometry and synthesis.5 The reductive amination of 1,4-diketones with sodium cyanoborohydride and ammonium acetate has yielded various 2,5-dialkyl-pyrrolidines that occur in the poison glands of ants of Monomorium spp.6... 

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See also in sourсe #XX -- [ , , ]

See also in sourсe #XX -- [ , , ]

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