Active-latent concept

Application of the Active-Latent Concept in Oligosaccharide Syntheses.72... 

Scheme 33 The active-latent 2 -carboxybenzyl glycosides concept and oligosaccharide synth eses [91]...

A very important contribution in this socio-technical era is made by Reason (Reason, 1990). He made a distinction between active failures, and latent conditions. The active failures are in general failures made by those at the sharp end of the accident causation (e.g. technical and human failures). Effects are felt almost immediately. Latent conditions are removed in time and space from the sharp end of the accident causation (e.g. organizational and technical failures) creating conditions for active failures to be made. A strict boundary between both concepts cannot be made and in reality can be seen as a sort of sliding transition. Here, the two concepts are separated... 

An interesting approach to both enantiomers of biologically active cyclo-phellitol, based on the latent symmetry concept, from the same common starting material D-xylose was proposed by Kireev et. al. Functionalization of this monosaccharide at the C-l provided compound 64, while similar processes initiated from the end (C5) afforded the ent-64 (Fig. 23).36 Proper functionalization of these intermediates led to both enantiomers of cyclophellitol. 

According to this concept, an active leaving-group LGa can be selectively activated over a latent (unreactive) LGb in the presence of a suitable activator A (Scheme 20). Subsequently, the latent LGb of the disaccharide is converted into the LGa this is... 

Early on, random glycosylation of unprotected disaccharides, involving the nonselec-tive coupling of a fucosyl donor, was used to produce three sub-libraries of a-fucosylated disaccharides in one step (136). Nearly statistical mixtures of all possible trisaccharides were obtained after chromatography. Linear and branched trisaccharide libraries were prepared by the latent-active glycosylation (137, 138). This concept made use of the convenient access to both glycosyl donors and acceptors from common allyl glycoside precursors. 

It is evident that the distribution of an agent is highly dependent on its ability to penetrate semi-permeable membranes. The plasma membrane is discussed in Section 5.4. In the classical conception of this membrane, its behaviour was static, something like a dialysis sac. More recent work discovered its latent dynamic properties, such as phase-reversal and processes akin to enzymic activity (e.g. permease activity, and transport in response to the metabolism of glucose). In the following pages, membranes will be discussed according to their observed functions and classified as four main types. 

The study of patient safety is the study of complexity. The study of complexity invites us to understand key concepts that can be applied to patient safety. Basic concepts from the fleld of patient safety are sharp and blunt end active and latent failure the Swiss Cheese Model of Accident Causation slips, lapses, and mistakes and hindsight bias and the fundamental attribution error. Key concepts from organizational analysis, such as normalization of deviance, diffusion of responsibility, tightly coupled work processes, and sensemaking, introduce practical lessons from high-reliability organizations. Application of specific lessons to health care are explored in Chapter Five. 

In conclusion, preliminary results confirmed the concept of using active and latent thioglycosyl donors in glycoside synthesis. The methodology is complementary to the armed and disarmed strategies [10] and should add another controllable variable in blockwise oligosaccharide syntheses. 

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