We have demonstrated that a new class of l-proline-based organic compounds catalyzed the direct aldol reaction between aldehydes and acetone to provide beta-hydroxy ketones in good yields. The reaction is efficient, and 5-10 mol % of the catalyst and excellent enantioselectivities (97-99% ee) were obtained in both aromatic and aliphatic aldehydes. The presence of a gem-diphenyl group at the beta-carbon is necessary for high enantioselectivity.

Organocatalysts have emerged as a third major way of catalyzing a wide variety of reactions, besides metal catalysts and biocatalysts. They have gained tremendous importance because of their green chemistry perspective. The criteria for green chemistry would be largely fulfilled if the major component of the reaction mixture, i.e. the solvent, is water which is a suitable solvent in various biosynthetic reactions. In this feature article we have described reactions promoted by organocatalysts in a large excess of water, without any organic solvent or excess of any reactant. We have also explained the structural features required for organocatalysts to work well in aqueous media.

We describe a lasso peptide, albusnodin, that is post-translationally modified with an acetyl group, the first example of a lasso peptide with this modification. Using heterologous expression, we further show that the acetyltransferase colocalized with the albusnodin gene cluster is required for the biosynthesis of this lasso peptide. This type of lasso peptide is widespread in Actinobacteria with 44 examples found in currently sequenced genomes.