Single step transformation

Tandem reaction strategies can accomplish several synthetic objectives in a single step.6 The rapidity with which they can build up molecular complexity is a most useful and impressive virtue. For example, cation-induced, biomimetic polyolefinic cyclizations7 are among the most productive and atom-economical8 single-step transformations known in organic chemistry. In one of the most spectac-... 

Synthesis is the application of one or more reactions to the preparation of a particular target compound, and can pertain to a single-step transformation or to a number of sequential steps. The selection of a reaction or series of reactions for a synthesis involves making a judgment about the most effective possibility among the available options. There may be a number of possibilities for the synthesis of a particular compound. For example, in the course of learning about the reactions in Chapter 1 to 12, we will encounter a number of ways of making ketones, as outlined in the scheme that follows. 

This will not work as no synthetic method for such a single-step transformation exists ... 

This is one of the finest single-step transformations in the chemical literature. Note that five reactions are achieved in one pot hydrogenation of two double bonds, Cbz deprotection, intramolecular imine formation, and convex-face alkene hydrogenation that establishes the n-Pr stereocenter. 

The systems described in Scheme 4.49 are for simple single-step transformations, typically with in-line purification however, the real opportunities presented by flow techniques will be multistep transformations occurring both in series and in parallel. Initial work in this field has already resulted in the total synthesis of natural products, such as grossamide [88] and ( )-oxomaritidine [89], and the drug candidate BMS-275291 [90], which are discussed later. 

This is understood to mean that a neutron is absorbed by a nucleus of 13AI and gamma radiation is emitted, resulting in the formation of a product nucleus f Al. The product nucleus of a nuclear reaction can be either stable or radioactive. If the product nuclide is radioactive, it will eventually decay to a different nuclide. The most common modes of decay are emission of alpha particles, beta particles, and gamma rays other particles or radiations can also be emitted in radioactive decay, but they are of little analytical utility and will not be discussed here. Radioactive decay may involve a single-step transformation or may proceed through a series of steps. An example of the former is... 

Haggam and co-workers have reported a new single-step transformation of readily available nitroarenes (321) with trialkyl phosphites, which could be performed both under thermal and microwave conditions, to give dialkyl A-arylphosphoramidates (322) in good yields and in short reaction times (Scheme 72). ... 

The combination of palladium(II) catalysts with stoichiometric amounts of cop-per(I I) salts as oxidants allowed the subsequent development of further diamination reactions. A particularly attractive approach to cychc guanidines 144 from easily accessible precursors 143 was realized within such a diamination reaction of alkenes (Scheme 16.38) [SK)]. It is interesting to note that the reaction proceeds already with copper(II) dichloride and with unprecedentedly enhanced rates also for piperidine formation. The selection of carbamate protecting groups readily provides the free guanidinium products within a single-step transformation. 

This chapter, of rather mixed composition, shows interesting single-step transformations from pyrethroid acids of initial interest to acids which researchers hoped would provide components for more active insecticides. 

Acetylene dicarboxylate reacts with the DABCO-derived acylammonium salts 80 in the presence of K2CO3 to give 2(5)-substituted furan-3,4-dicarboxylates 81 in a single-step transformation [26] ... 

The NbN synthesis occurs at relatively high temperature with no intermediate features (19). The H2O peak at 1160 K represents a single step transformation of 2 5 NbNxOj.x intermediate (20). No Nb02 phase has been... 

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