Aqueous organocatalyzed aldol reaction of glyoxylic acid for the enantioselective synthesis of α-hydroxy-γ-keto acids

N-Tosyl-(Sa)-binam-L-prolinamide is an efficient catalyst for the aqueous aldol reaction, between glyoxylic acid, as monohydrate or aqueous solution, and ketones. This reaction led to the formation of chiral α-hydroxy-γ-keto carboxylic acids in high levels of diastereo- and enantioselectivities achieving mainly anti aldol products.

Effect of commercial amino acids on iron nutrition of tomato plants grown under lime-induced iron deficiency

The objective of this work was to study the effect of root and foliar application of two commercial products containing amino acids from plant and animal origin on iron (Fe) nutrition of tomato seedlings cultivated in two nutrient media: lime and normal nutrient solutions. In the foliar-application experiment, each product was sprayed with 0.5 and 0.7 mL L–1 2, 7, 12, and 17 d after transplanting. In the root application experiment, 0.1 and 0.2 mL L–1 of amino acids products were added to the nutrient solutions. In both experiments, untreated control plants were included as well. Foliar and root application of the product containing amino acids from animal origin caused severe plant-growth depression and nonpositive effects on Fe nutrition were found. In contrast, the application of the product from plant origin stimulated plant growth. Furthermore, significantly enhanced root and leaf FeIII-chelate reductase activity, chlorophyll concentration, leaf Fe concentration, and FeII : Fe ratio were found in tomato seedlings treated with the product from plant origin, especially when the amino acids were directly applied to the roots. These effects were more evident in plants developed under lime-induced Fe deficiency. The positive results on Fe uptake may be related to the action of glutamic acid, the most abundant amino acid in the formulation of the product from plant origin.

Glyoxylic Acid versus Ethyl Glyoxylate for the Aqueous Enantio­selective Synthesis of α-Hydroxy-γ-Keto Acids and Esters by the N-Tosyl-(S a)-binam-l-prolinamide-Organocatalyzed Aldol Reaction

N-Tosyl-(S a)-binam-l-prolinamide is an efficient catalyst for the aqueous aldol reaction between ketones and glyoxylic acid, as the monohydrate or as an aqueous solution, or a 50% toluene solution of ethyl glyoxylate. These reactions led to the formation of chiral α-hydroxy-γ-keto carboxylic acids and esters in high levels of diastereo- and enantioselectivities (up to 97% ee), providing mainly anti aldol products. Only cyclopentanone and cyclohexane-1,4-dione afforded an almost 1:1 mixture of the syn/anti-diastereoisomers; however, the reaction between 4-phenylcyclohexanone and ethyl glyoxylate gave the corresponding syn,syn-product as the major diastereoisomer.