70005-01-5

Upstream product

• 34713-70-7 2-Phenylpropanal 
• 70005-02-6 rac-E-2-phenyl-propionaldehyde oxime 
• 100-42-5 styrene 
• 201230-82-2 carbon monoxide 

Downstream Products

• 70005-02-6 rac-E-2-phenyl-propionaldehyde oxime 

Relevant academic research and scientific papers

Focused Directed Evolution of Pentaerythritol Tetranitrate Reductase by Using Automated Anaerobic Kinetic Screening of Site-Saturated Libraries

This work describes the development of an automated robotic platform for the rapid screening of enzyme variants generated from directed evolution studies of pentraerythritol tetranitrate (PETN) reductase, a target for industrial biocatalysis. By using a 96-well format, near pure enzyme was recovered and was suitable for high throughput kinetic assays; this enabled rapid screening for improved and new activities from libraries of enzyme variants. Initial characterisation of several single site-saturation libraries targeted at active site residues of PETN reductase, are described. Two mutants (T26S and W102F) were shown to have switched in substrate enantiopreference against substrates (E)-2-aryl-1-nitropropene and α-methyl-trans-cinnamaldehyde, respectively, with an increase in ee (62 % (R) for W102F). In addition, the detection of mutants with weak activity against α,β-unsaturated carboxylic acid substrates showed progress in the expansion of the substrate range of PETN reductase. These methods can readily be adapted for rapid evolution of enzyme variants with other oxidoreductase enzymes.

Switchable Enantioselective Three- and Four-Dimensional Dynamic Gas Chromatography-Mass Spectrometry: Example Study of On-Column Molecular Interconversion

A novel hybrid online enantioselective four-dimensional dynamic GC (e4D-DGC) approach to study reversible molecular interconversion through specific isolation of a diastereo and enantiopure oxime, 2-phenylpropanaldehyde oxime, from prior multidimensional separation, is described. It incorporates a pre-enantioseparation step that applies comprehensive two-dimensional GC (GC × GC), prior to multiple microfluidic (Deans) switching for selection of components of a diastereomeric (E,Z) and enantiomeric (R,S) oxime into a third reactor column where isomerization occurs. This is followed by E/Z separation in a fourth analytical column. The enantioselective first dimension (1Denant) yields enantioseparation of E(R), Z(R), E(S), and Z(S) isomers, with a characteristic interconversion zone between the E and Z isomers. However, these are contaminated with underlying stereoisomers. Selected separation regions were then modulated and separated using a second dimension (2D) column via GC × GC, resolving the interfering stereoisomers. Individual pure enantiomers were then selectively heart-cut from within the 2D separation space, cryofocused, then eluted on a 3D reactor column for E ? Z isomerization under controlled oven temperature and flow. Heart-cuts taken over the resulting interconversion distribution were cryotrapped at the inlet of a 4D column, on which achiral separation allows precise quantification of each E and Z isomer of the enantiomer. From peak areas and isomerization time, the forward and backward rate constants (kE→Z and kZ→E) were determined. The described methodology is suited to other configurationally labile molecules (for instance, hydrazones and imines), which exhibit isomerization, and can be used to isolate individual compounds from multicomponent samples, without requiring pure compound synthesis, or complex mathematical models or in-silico simulations.

One-pot synthesis of aldoximes from alkenes: Via Rh-catalysed hydroformylation in an aqueous solvent system

Aldoxime synthesis directly starting from alkenes was successfully achieved through the combination of hydroformylation and subsequent condensation of the aldehyde intermediate with aqueous hydroxylamine in a one-pot process. The metal complex Rh(acac)(CO)2 and the water-soluble ligand sulfoxantphos were used as the catalyst system, providing high regioselectivities in the initial hydroformylation. A mixture of water and 1-butanol was used as an environmentally benign solvent system, ensuring sufficient contact of the aqueous catalyst phase and the organic substrate phase. The reaction conditions were systematically optimised by Design of Experiments (DoE) using 1-octene as a model substrate. A yield of 85% of the desired linear, terminal aldoxime ((E/Z)-nonanal oxime) at 95% regioselectivity was achieved. Other terminal alkenes were also converted successfully under the optimised conditions to the corresponding linear aldoximes, including renewable substrates. Differences of the reaction rate have been investigated by recording the gas consumption, whereby turnover frequencies (TOFs) >2000 h-1 were observed for 4-vinylcyclohexene and styrene, respectively. The high potential of aldoximes as platform intermediates was shown by their subsequent transformation into the corresponding linear nitriles using aldoxime dehydratases as biocatalysts. The overall reaction sequence thus allows for a straightforward synthesis of linear nitriles from alkenes with water being the only by-product, which formally represents an anti-Markovnikov hydrocyanation of readily available 1-alkenes.

Cyanide-Free and Broadly Applicable Enantioselective Synthetic Platform for Chiral Nitriles through a Biocatalytic Approach

A cyanide-free platform technology for the synthesis of chiral nitriles by biocatalytic enantioselective dehydration of a wide range of aldoximes is reported. The nitriles were obtained with high enantiomeric excess of >90 % ee (and up to 99 % ee) in many cases, and a “privileged substrate structure” with respect to high enantioselectivity was identified. Furthermore, a surprising phenomenon was observed for the enantiospecificity that is usually not observed in enzyme catalysis. Depending on whether the E or Z isomer of the racemic aldoxime substrate was employed, one or the other enantiomer of the corresponding nitrile was formed preferentially with the same enzyme.

Laccase-catalysed biotransformation of collismycin derivatives. A novel enzymatic approach for the cleavage of oximes

Analogues of the natural product collismycin bearing a carboxylic acid moiety has been efficiently synthesised from several collismycin precursors through a laccase-catalysed oxidation under mild conditions with TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) as a mediator and aerial O2 as an oxidant in aqueous medium. The biotransformations proceeded with excellent yields (85-95%) and involved, depending on the precursor, the oxidation of a benzylic hydroxyl group or the bioconversion of an aldoxime group into carboxylic acid. Since the latter is herein reported for the first time, we explored the potential of this novel oxime cleavage with several synthetic aldo- and ketoximes. Thus, the laccase/TEMPO system proved to be an efficient and green alternative for the deprotection of both aromatic and aliphatic ketoximes into the corresponding ketones. On the other hand, the reaction with aldoximes leads to dimeric species generated by coupling reactions.