Papers of particular interest, published within the period of review, have been highlighted

as: • of special interest “
“Performing reaction sequences in one pot in a sequential or even simultaneous fashion avoids time-consuming or yield-reducing isolation and purification of the intermediates [1 and 2]; as a consequence the amount of chemicals/solvents required for extraction/purification of intermediates is minimised leading to an improved E factor [3]. Cascades involving reduction selleck kinase inhibitor as well as oxidation steps are still a challenge due to the diverging reaction conditions. Since in living cells oxidation and reduction processes are performed simultaneously, enzymes are probably the perfect catalysts to be exploited for synthetic redox cascade applications [4]. In this review, artificial cascades involving an oxidation step followed by a reduction step, or vice versa, will be discussed, whereby at least one redox step is catalysed by an enzyme. The focus is on cascades published during the past 4 years. Cascades employing fermenting cells or involving in vivo metabolism will not be discussed as well as concepts for cofactor/cosubstrate recycling; furthermore, cascades involving the catalase-promoted disproportionation of hydrogen peroxide are out of scope. The easiest approach to performing such

redox cascades is to run the first redox reaction Beta adrenergic receptor kinase until completion and then start the second step by adding the required reagents; thus, the two steps are separated by selleck chemicals llc time but performed in the same pot. More challenging is to run the two redox reactions at the same time, thus simultaneously in one pot. Here two cases can be distinguished: The simpler case is that the oxidation and the reduction steps are working independently of each other; thus, reagents for the oxidation step as well as for the reduction step are required. The more demanding case is that the oxidation and reduction steps are interconnected: it would

be desirable that the formal electrons gained in the oxidation step are consumed in the reduction step. This represents a redox neutral cascade; thus, in an ideal case no additional reducing or oxidising agents are required. Consequently, the review was subdivided into the following subsections (Figure 1): (1a) simultaneous redox neutral oxidation–reduction cascades, (1b) simultaneous independent redox cascades in one pot and (2) subsequent oxidation–reduction cascades performed in one pot but separated by time. The (bio)catalysts working in concert in simultaneous oxidation–reduction cascades can be regarded as an interactive catalyst network. In the special case of redox neutral cascades, it represents an interconnected catalyst network.