Aspects of stereocontrol in the L-Selectride reduction of 4-acyl-1,3-dioxolane derivatives

Divergent Oxidation Reactions of E- and Z-Allylic Primary Alcohols by an Unspecific Peroxygenase

Unspecific peroxygenases (UPOs) catalyze the selective oxygenation of organic substrates using only hydrogen peroxide as the external oxidant. The PaDa-I variant of the UPO from Agrocybe aegerita catalyses the oxidation of Z- and E-allylic alcohols with complementary selectivity, giving epoxide and carboxylic acid/aldehyde products respectively. Both reactions can be performed on preparative scale with isolated yields up to 80 %, and the epoxidations proceed with excellent enantioselectivity (>99 % ee). The divergent reactions can also be used to transform E/Z mixtures of allylic alcohols, enabling both product series to be isolated from a single reaction. The utility of the epoxidation method is exemplified in the total synthesis of both enantiomers of the insect pheromone disparlure, including a highly enantioselective gram-scale transformation. These reactions provide further evidence for the potential of UPOs as catalysts for the scalable preparation of important oxygenated intermediates.

Total synthesis and chemical stability of pseudouridimycin

We report the chemical synthesis of pseudouridimycin (1), an antimicrobial natural product that potently and selectively inhibits bacterial RNA polymerase. Chemical stability studies revealed intramolecular hydroxamate bond scission to be...

Rhodium(ii)-catalysed tandem aziridination and ring-opening: stereoselective synthesis of functionalised tetrahydrofurans

Rh(ii) mediated tandem aziridination and cycloetherification achieves a direct, stereoselective synthesis of the 2-(1-amino-2-hydroxyethyl)tetrahydrofuran motif.

Practical synthesis of 2-keto-3-deoxy-D-glycero-D-galactononulosonic acid (KDN)

Reaction of propargylmagnesium bromide with 2,3;5,6-di-O-isopropylidene-D-mannonolactone followed by highly stereoselective reduction of the so-formed lactol with sodium borohydride gives a syn-diol from which practical syntheses of 2-keto-3-deoxy-D-glycero-D-galactononulosonic acid (KDN) and various partially protected derivatives have been achieved all of which feature the oxidative unmasking of the α-keto acid moiety from the alkyne.