Disconnections other

The cis stereochemistry of (7) is irrelevant to (10 or (11), as cyclisation can give only ais fusion of two five-membered rings, but it might be a problem for (9). In any case, no disconnection, other than removing single carbon atoms, can easily be made on (9). Much the same is true of (12), but reconnection of the 1,6-dicarbonyl in (13) provides a good starting material (14). 

The new connective sites provide the opportunity to destroy or disconnect other regions of the nanostructure without destruction of the entire nanoscale entity. This was demonstrated by the excavation of the core of shell crosslinked polymer micelles, by the removal of the colloid from colloidally templated... 

If preferred, the following alternative procedure may be adopted. The absolute alcohol is placed in a 1 5 or 2 litre three-necked flask equipped with a double surface reflux condenser and a mercury-sealed mechanical stirrqr the third neck is closed with a dry stopper. The sodium is introduced and, when it has reacted completely, the ester is added and the mixture is gently refluxed for 2 hours. The reflux condenser is then rapidly disconnected and arranged for downward distillation with the aid of a short still head or knee tube. The other experimental details are as above except that the mixture is stirred during the distillation bumping is thus reduced to a minimum. 

This then is the disconnection corresponding to the reaction. It is the thinking device we use to help us work out a synthesis of t-butyl alcohol. We could of course have broken any other bond in the target molecule such as ... 

Alcohols are key functional groups in synthesis because their synthesis can be plaimed by an important disconnection and because they can be converted into a whole family of other functional groups. List three types of molecule you might make from an alcohol by FGI. 

You should have two possible alcohols as the next step back, choosing one of these because it gives a useful disconnection while the other does not. 

So we can disconnect any a,p-imsaturated carbonyl compound along the double bond, writing CH2 at one end and C=0 at tbe other. 

Analysis The branchad chain can only be made by reduction of an oxime so we must disconnect the other (benzyl) side first. 

Analysis Symmetiy suggests that one of the two possible cyclobutane disconnections is better than other ... 

The generation of loops is necessary because disconnected regions are often separated by a section where a few amino acids have been inserted or omitted. These are often extra loops that can be determined by several methods. One method is to perform a database search to find a similar loop and then use its geometric structure. Often, other conformation search methods are used. Manual structure building may be necessary in order to find a conformation that connects the segments. Visual inspection of the result is recommended in any case. 

Since (A) does not contain any other functional group in addition to the formyl group, one may predict that suitable reaction conditions could be found for all conversions into (A). Many other alternative target molecules can, of course, be formulated. The reduction of (H), for example, may require introduction of a protecting group, e.g. acetal formation. The industrial synthesis of (A) is based upon the oxidation of (E) since 3-methylbutanol (isoamyl alcohol) is a cheap distillation product from alcoholic fermentation ( fusel oils ). The second step of our simple antithetic analysis — systematic disconnection — will now be exemplified with all target molecules of the scheme above. For the sake of brevity we shall omit the syn-thons and indicate only the reagents and reaction conditions. 

To identify the carbonyl compound and the ylide required to produce a given alkene mentally disconnect the double bond so that one of its carbons is derived from a car bonyl group and the other is derived from an ylide Taking styrene as a representative example we see that two such disconnections are possible either benzaldehyde or formaldehyde is an appropriate precursor... 

We can improve the starting performance of the above method by providing C in two parts, one for start Cl, of a much higher value, depending upon the requirement of 7, through a disconnect switch (Figures 1.25(fl2) and (bi)), and the other C, for a run of a much lower value (so that... 

If relays, instruments and other auxiliary apparatus, have a voltage other than the main voltage, they should be disconnected from the main circuit, while conducting this test and tested separately, according to their voltage rating as shown in Table 14.3. 

As a standby for emergency use in case of accidental release of toxic materials, e.g. during tanker unloading, or disconnection of temporary pipelines or when dealing with spillages generally, or if other protective measures, e.g. local exhaust ventilation, fail in service. 

Alkyl, arylalkyl, aryl, and other building-block type groups should not be internally disconnected (preserved bonds). 

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