Fructose reaction with dicarbonyl compounds

Another class of pyrrole derivative may be obtained by the interaction of l-amino-l-deoxy-2-ketoses or 2-amino-2-deoxyaldoses with a jQ-dicarbonyl compound. Unlike the previous type (which is N-substituted), these pyrrole derivatives have a tetrahydroxybutyl group in the a- or /8-position with respect to the nitrogen atom of the ring, in addition to other groups arising from the dicarbonyl compound used in the condensation. The formation and reactions of this type of pyrrole derivative have been discussed in detail in two articles in this series48,49 they will, therefore, only be treated briefly. 1-Amino-l-deoxy-D-fructose (53) reacts with 2,4-pentanedione to give50 pyrrole derivative 54a similar pyrroles were obtained with ethyl acetoace-tate,50,51 which yields 54b. 

Monosaccharides react with a variety of 1,3-dicarbonyl compounds in the presence of zinc chloride in ethanolic or aqueous solution to yield substituted furans (Scheme 69) (56MI31200). The reaction of ethyl acetoacetate with D-glucose and D-mannose yielded the trisubstituted furan (252) in 20% yield, while D-fructose under similar conditions yielded (253 7%). These products have been used for the synthesis of dehydromuscarones (63HCA1259). Oxidation of the tetrahydroxybutyl side chains with lead tetraacetate gives the aldehyde, which can be converted to the corresponding acid with alkaline silver oxide. 

The reaction of 1-amino-l-deoxy-D-fructose with /3-dicarbonyl compounds in aqueous acetone at neutral pH has also been studied. The acetate of this amino sugar affords, with ethyl acetoacetate, ethyl 2-methyl-4-(D-om6wo-tetrahydroxybutyl)pyrrole-3-carboxylate (17). As in previous... 

By reaction of serine or phenylalanine with fructose instead of glucose we got identical results with the exception of higher pyra-zine concentrations (more than 50 % relatively higher ). Main products have been 2,5 and 2,6-dimethylpyrazine which may be formed via the reaction of two C,-dicarbonyls each. In our opinion these results demonstrate a specialise of fructose to decompose by chain cleavage. As another decomposition product of fructose we have identified furfurylalcohol after heating a reaction mixture at 120° C. Obviously this Cg-compound has been formed after cleavage of the carbon atom 1 from the sugar molecule. 

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