The Phytochemical Reduction of Heterocyclic Compounds

Neuberg, Lustig and Cagan were able to reduce furoin to hydro-furoin by the action of fermenting yeast  

The formation of furoin from furil represents the simplest and quickest demonstration of phytochemicai reduction for lecture purposes. The presence of the acyloin can be demonstrated, even in extreme dilution, by its characteristic reaction with aqueous or alcoholic sodium hydroxide (deep blue-green color with deep violet-red dichroic irridescence). This reaction can be carried out in unfiltered fermentation mixtures it gives positive results after thirty seconds. The addition of a few crystals of commercially available furil dissolved in one cc. alcohol to a fermenting sugar solution is suflBcient for demonstration.  

The phytochemicai reduction of acetylfurylcarbinol takes place so rapidly that it cannot be isolated during carboligatic formation of this acyloin, the corresponding methylfurylethylene glycol being obtained directly.  

2-Thiophene-carbinol is synthesized from 2-thiophene aldehyde by fermenting yeast. The behavior of 2,2 thenoin and 2,2 thenil on bioreduction is exactly analogous to that of furoin and furil.  

Ideas regarding the mechanism of phytochemical reduction of olefins have been advanced by Fischer and Eysenbach. They also point out that just as in the case of the simple disproportionations in the course of sugar degradation (for example, the second and third forms of fermentation), saturation of the olefinic linkage is at an optimum in the weakly alkaline range, at about pH 8.5. 

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