An efficient practical chemo-enzymatic protocol for the synthesis of pyrazoles in aqueous medium at ambient temperature

• This is the first eco-efficient report for the synthesis of title compounds using biocatalysis.
• Synthesis of pyrazole structural motifs expedited by fermenting baker's yeast.
• The role of baker's yeast in the reaction mechanism has been studied.
• Easy access of biologically important pyrazole structural cores from less reactive hydrazines and hydrazides.

An expeditious oxidative cyclocondensation reaction of hydrazines/hydrazides with 1,3-dicarbonyl compound was efficiently developed in aqueous medium using Saccharomyces cerevisae (baker's yeast) as a whole cell biocatalyst at room temperature. The method has been assigned using green chemistry measures and found to give a range of N-substituted pyrazoles with moderate to excellent yields (70–92%). The reaction progress was monitored by gas chromatography.

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