Cascade reactions product studies

A systematic exploration of the intramolecular [4+2]/[3+2] cycloaddition cascade of 1,3,4-oxadiazoles was described. The studies permit the use of unsymmetrical dienophiles, dipolarophiles, and oxadiazoles as well as to control the cycloaddition regioselectivity and diastereoselectivity. The scope and utility of the reaction were defined <2006JA10589>. The tandem intramolecular [4+2]/[3+2] cycloaddition cascade reaction of 1,3,4-oxadiazole was applied to the syntheses of a series of natural products including a total synthesis of (-)- and ent-(+)-vindoline <2006JA10596>. 

Fig. 23.7. Dynamics of an enzymatic reaction in lipid nanotube networks with variable topology numeric calculations (bottom)/fluorescence intensity of the reaction product (top) vs. time for three differently chosen network geometries, (a) Reference experiment a static four-vesicle network. The product concentration displays a cascade-like behavior in time and space, (b) Linear-to-circular topology change in the four-vesicle network (c) A model study of the effect of product inhibition as the linear four-vesicle network (top panel) undergoes the same change in structure (bottom panel) as the network in the reference experiment ([28], reprinted with permission)...

A kinetic study, using complex pathways simulator (COPASI) software, NMR spectroscopy, and product studies, has shown that the endo-selective epoxide-opening cascade or domino reaction by H2O converting the diepoxy alcohol (7) into the tetrahydropyran triad (8) in neutral water proceeds by a stepwise mechanism initiated by a slow, low regioselective endo.exo = 2.0 1) 5 2 reaction that is followed by a fast, highly regioselective endo exo = 19 1) 5 2 reaction. ... 

In this chapter, we have summarized striking examples of cascade reactions for the chemo-enzymatic synthesis of glycoconjugates. The benefit of cascade reactions without intermediate product work-up is emerging in the field of glycan synthesis. Future studies should be therefore directed toward biocatalyst engineering and process design to match the requirements for sequential, one-pot, and convergent cascade reactions. 

Nicotinic acid has a wide range of therapeutic uses, and can be manufactured from 3-cyanopyridine using a NHase/amidase cascade. The control of this cascade reaction in M. imperiale by operational parameters was studied in continuous reactors to optimize the production of nicotinic acid ([39, 40] for details, see Chapter 13). Its analog, 2-chloronicotinic acid, a building block of pesticides and pharmaceuticals, was also produced from the corresponding nitrile by NHase/amidase using R. erythropolis ZJB-09149 [41]. 

Following their initial studies on the real structure of ( )-berkelic acid previously mentioned, Fiirstner and coworkers published in 2010 a total synthesis of this natural product. The successful route was based on an aldol reaction between methyl ketone 13 and benzaldehyde derivative 14 to give enone derivative 12 (Scheme 3). A subsequent deprotection/1,4-addition/ spiroacetalization cascade reaction delivered the tetracyclic core 11. Installation of the lateral chain was achieved by oxidative rupture, reduction, and... 

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