Stereoselectivity of Enzymatic Hydrolyses and Acylations

Reagents for (ir)reversible enzymatic acylations.

Commonly, hydrolase-catalysed reactions are used for kinetic resolutions of alcohols, amines and acids. Only a few applications in total syntheses have been described. Most of these examples are for the synthesis of amides and peptides. Here, the synthesis of all the different types of activated acids that can be applied in hydrolase-catalysed acylations is described. The application of these a...

Regioselective enzymatic acylations of polyhydroxylated eudesmanes: semisynthesis, theoretical calculations, and biotransformation of cyclic sulfites.

Different lipase enzymes have been tested in order to perform regioselective acetylations on the eudesmane tetrol from vulgarin. High yields (95%) of 1,12-diacetoxy derivative (4) were achieved in 1 h with Candida antarctica lipase (CAL). However, only the 12-acetyl derivative (6) was obtained in similar yield with Mucor miehei (MML) or Candida cylindracea (CCL) lipases. The enzymatic protectio...

Operational control of stereoselectivity during the enzymatic hydrolysis of racemic organophosphorus compounds.

The wild-type bacterial phosphotriesterase catalyzes the stereoselective hydrolysis of racemic pairs of organophosphorus compounds. The enzymatic stereoselectivity can be substantially enhanced via systematic alteration of the pKa for the leaving group phenol in the target substrates. These changes alter the rate-limiting step for substrate turnover from a diffusional event to phosphorus-oxygen...

Site‐Selective Acylations with Tailor‐Made Catalysts

The acylation of alcohols catalyzed by N,N-dimethylamino pyridine (DMAP) is, despite its widespread use, sometimes confronted with substrate-specific problems: For example, target compounds with multiple hydroxy groups may show insufficient selectivity for one hydroxyl, and the resulting product mixtures are hardly separable. Here we describe a concept that aims at tailor-made catalysts for the...

Studies of Regio- and Stereoselectivity