ChemCatChem: Cluster Issue on Chemoenzymatic Synthesis

Abstract

A permanent challenge that chemists in the field of (stereoselective) organic synthesis face, is the search for the ideal type of (catalytic) reaction and catalyst for their desired transformation. At this stage, often the fields of biocatalysis and chemocatalysis/"classic" chemical synthesis are considered as "competitors". Besides this question of which is the better choice for a specific synthetic task it is, however, important to state that both fields represent attractive and widely applied technologies, thus making valuable solutions for challenging organic synthetic transformations (and technical-scale processes) possible. Accordingly, rather than looking at the clear differences that separate these fields, it might be a promising alternative to focus on what unifies them. The combination of chemocatalysis and biocatalysis in multistep organic synthetic processes has turned out to be of high interest, and, for example, running these processes without isolation of an intermediate as an one-pot process can also further contribute to the development of more sustainable synthetic methods, as time-and capacity-consuming steps, as well as waste-producing steps, can be minimized. Based on the tremendous contributions made already in the field of chemoenzymatic synthesis, this field offers exciting perspectives for the future development of both highly efficient and sustainable synthetic processes. Also an increased number of technical scale operations of such concepts can certainly be expected in the future. This cluster issue about chemoenzymatic syntheses presents the current progress in this exciting field.A Minireview from the group of Park and Kim reflects the impressive state of art in dynamic kinetic resolution of amines and amino acids by means of a combination of metal-catalyzed racemization and enzymatic resolution. Furthermore, the same group reports new results of an efficient Ru complex for racemization of chiral secondary alcohols and the extension of Discover this journal online at:

A Chemoenzymatic Route to the (+)-Form of the Amaryllidaceae Alkaloid Narseronine

“…After a further 2 h the ensuing mixture was cooled to 188C then concentrated under reduced pressure. The resulting orange oil was subjected to flash chromatography (silica, 2 % v/v ammonia-saturated methanol/dichloromethane elution (3aS,5R,12cS)-5-Hydroxy-2,3,3a,4,5,12c-hexahydro- [1,3]dioxolo[4 0 ,5 0 :6,7]isochromeno [3,4-g]indol-7(1H)-one (22) A magnetically stirred solution of ketone 21 (73 mg, 0.25 mmol) and CeCl 3 Á7H 2 O (92 mg, 0.38 mmol, 1.5 equiv.) in methanol (10 mL) was cooled to À788C and, after 0.25 h, treated with sodium borohydride (11.3 mg, 0.03 mmol, 1.2 mol equiv.)…”

“…(3aS,5R,12cS)-5-Hydroxy-2,3,3a,4,5,12c-hexahydro- [1,3]dioxolo-[4 0 ,5 0 :6,7]isochromeno [3,4-g]indol-7(1H)-one [(þ)-2, (þ)-Narseronine] A magnetically stirred solution of alcohol 22 (18.6 mg, 0.06 mmol) in dry THF (2 mL) maintained at 08C under a nitrogen atmosphere, was treated, in portions, with potassium hydride (32 mg of a 30 % dispersion in mineral oil, 0.24 mmol, 4.0 mol equiv.) and then with methyl iodide (30 mL, 0.48 mmol, 8.0 mol equiv.)…”

“…[1,2] Metabolites such as 1 have proved to be particularly effective starting materials for the chemical synthesis of a remarkably diverse range of chiral, non-racemic natural products and/or biologically active compounds. [2] However, an ongoing issue associated with this (chemoenzymatic [3] ) approach to the construction of such target systems is the seeming confinement of it to the generation of a single enantiomeric form of a given target molecule. [4] As part of an effort to address such constraints, Hudlicky and his coworkers demonstrated that the 'latent' symmetry elements associated with compound 1 and certain of its congeners [2a,d] allow their use in the enantiodivergent synthesis of, inter alia, cyclitols.…”

An Efficient Chemoenzymatic Approach towards the Synthesis of Rugulactone

“…Biocatalysis has long been known as an alternative technology, capable of delivering highly stereo-, chemo-, and regioselective transformations [ 23 , 24 ]. Recent contributions demonstrate the broad diversity of impressive opportunities for chemoenzymatic processes, which underline their potential as valuable solutions for current synthetic challenges in the synthesis of valuable chiral building blocks towards the production of pharmaceuticals and biologically active natural products [ 23 , 24 , 25 , 26 ].…”

Editorial: Solving the Material and Energy Challenges of the Future

“…Biocatalysis and chemical synthesis do not have to compete, but rather they should more often work 'hand in hand', as has been exemplified in the February 2011 special issue of ChemCatChem, [8] in which a range of examples demonstrate that enzymes can be used in one-pot reactions, thus enabling efficient multistep syntheses.…”