Plausible disconnection

Plausible disconnections dissonant three-membered rings... 

In contrast to "illogical disconnections", in "plausible disconnections" a reasonable or, at least, plausible mechanism exists which involves the motion of electron pairs and leads to stable fragments, either ions or molecules. In any case, however, the "principle of maximum simplicity" does not hold here, since one of the resulting fragments is always a dissonant three-membered ring. 

In connection with monofunctionalised molecules we have already referred to a "plausible disconnection" according to which an alcohol can be directly "disconnected" at the a-position, in such a manner that an epoxide rather than a carbonyl compound results, as for example in the case of the tertiary alcohol 14 ... 

This methodology, as in the cases of rearrangements and of plausible disconnections, does not meet the criterium of maximum simplicity, since the reconnection represents an increase of the "cyclic order" and therefore of the complexity of the molecule. 

Plausible disconnections of structures and recombination of dissociated parts (synthons) must take into account the quality of potential reaction centers, which could serve for dissociation or association. By quality of reaction centers, it can be understood as the preferable type of charge on the atom, given by the type of dissociation of a bond by heterolysis or homolysis, from which follows the affinity... 

Two plausible disconnections are presented in Scheme 2.24 (a) disconnection of the C-C bond between the a-C atom and carbonyl C atom and (b) disconnection of the C-C bond between the a- and 3-C atoms to the carbonyl group. Both disconnections follow the principle of maximal simplification of the target molecule. 

The alternative disconnection to CH3 and HCCH2CH2CH2CH3 reveals a plausible approach to 2-hexanol but is inconsistent with the requirement of the problem that limits starting materials to four carbons or fewer. The five-carbon aldehyde would have to be prepared first, making for a lengthy overall synthetic scheme. 

Taking this information together with the imaging data (MRI-CBV) maps demonstrating a hypermetabolic phase in very young AD and Down-syndrome mice and a later age-dependent hypometabolism (Moreno et al., 2006, 2007), it seems plausible to propose that this series of events leads to a biphasic neuronal disconnection syndrome, with an initial hyperactive state followed by subsequent synaptic failure phase (Fig. 12). 

I shall proceed on the plausible assumption that such a disconnect exists and is substantial. Why is it important to bridge or at least narrow the gap between engineering-related ethics education and the ethics realities of contemporary engineering practice ... 

The plausible retrosynthetic approaches to 1-3 envisage one or two C-C bond disconnections to arrive at 4 or 5 and Cg or C building blocks (Scheme 9.15). 

Sketch plausible retrosynthetic disconnections for the following molecules. [Hints For part b, see Section 17-10 for part c, see Problem 43 of Chapter 17.]... 

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