Carrots (Daucus carota)
Plant cell cultures and plant roots can be used to effect reductions in aqueous media offering mild, eco-compatible conditions. Reductases that, for example, are able to reduce carbonyl compounds to the corresponding alcohols are present in various plants; in particular, carrots often give good results.
In a set-up used by Janine Cossy (ESPCI ParisTech, France), a grid separates the stirbar from the carrot slices to avoid mashing the carrots. Two tubes have been added to generate a vortex and keep the substrate suspended in the aqueous solution - without this, the carrot slices will prevent the surface from being stirred and the substrate would accumulate on the surface. Using this experimental system at 1100 rpm, yields have been improved by 30% compared to standard stirring and the reaction time has been reduced from 5 days to 2 days in the reduction of cyclic 3-oxo-amines.
An efficient reduction of various prochiral ketones such as acetopehones, α-azido aryl ketones, β-ketoesters, and aliphatic acyclic and cyclic ketones to the corresponding optically active secondary alcohols with good chemical yield was achieved by using Daucus carota, root plant cells under extremely mild and environmentally benign conditions in aqueous medium.
J. S. Yadav, S. Nanda, P. T. Reddy, A. Bhaskar, Rao, J. Org. Chem., 2002, 67, 3900-3903.
Carrots (Daucus carota) were used as cheap, eco-compatible, and efficient reducing reagent for the conversion of cyclic amino-ketones into amino-alcohols in high yields and enantiomeric excesses. The procedure allows an easy access to precursors of biologically active products.
R. Lacheretz, D. G. Pardo, J. Cossy, Org. Lett., 2009, 11, 1245-1248.