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).

Asymmetric 'Clip-Cycle' synthesis of 3-spiropiperidines.

3-Spiropiperidines can be synthesized in up to 87% yield and 96 : 4 er using a two step 'Clip-Cycle' approach. The 'Clip' stage of this method is based on efficient and highly -selective cross metathesis of -Cbz-protected 1-amino-hex-5-enes with a thioacrylate. This is followed by the 'Cycle' step, in which an intramolecular asymmetric aza-Michael cyclization is promoted by a chiral phosphoric acid catalyst.

Preparative scale Achmatowicz and aza-Achmatowicz rearrangements catalyzed by unspecific peroxygenase.

The unspecific peroxygenase (UPO) from (rUPO-PaDa-I-H) is an effective and practical biocatalyst for the oxidative expansion of furfuryl alcohols/amines on a preparative scale, using the Achmatowicz and aza-Achmatowicz reaction. The high activity and stability of the enzyme, which can be produced on a large scale as an air-stable lyophilised powder, renders it a versatile and scalable biocatalyst for the preparation of synthetically valuable 6-hydroxypyranones and dihydropiperidinones. In several cases, the biotransformation out-performed the analogous chemo-catalysed process, and operates under milder and greener reaction conditions.

Photochemical Initiation and Reactions of Thiyl Radicals Studied with S2' Radical Traps.

A radical trapping method based on an S2' homolytic substitution reaction was applied to study the mechanism of a photochemical spirocyclisation of indole-ynones in the presence of thiols. Starting material, products and a range of trapped radical intermediates were simultaneously detected in reaction mixtures by mass spectrometry (MS). The trapped intermediates included both initiating and main chain propagating radicals.