Synthetic prediction

The synthesis is too advanced to give here but ii was remarkably economical and stereoselective, considering the complexity of (63), Still was able to carry out these three syntheses largely because of his confidence in his stereochemical and synthetic predictions. 

Although this procedure normally results in complete substitution, except for the sterically more demanding alkoxo groups, 100% synthetic predictability is not likely to be achieved. The generality and limitations of Eq. 2.41 for a wide variety of elements may be reflected by the group-wise discussion that follows. 

In more recent publications the analytical standards have been raised considerably (HPLC, H-NMR, CD R.F. Nutt, 1980), and one may predict that in the near future it will be possible to characterize fully synthetic oligopeptides of moderate size. 

The market penetration of synthetic fuels from biomass and wastes in the United States depends on several basic factors, eg, demand, price, performance, competitive feedstock uses, government incentives, whether estabUshed fuel is replaced by a chemically identical fuel or a different product, and cost and availabiUty of other fuels such as oil and natural gas. Detailed analyses have been performed to predict the market penetration of biomass energy well into the twenty-first century. A range of from 3 to about 21 EJ seems to characterize the results of most of these studies. 

The first synthetic polyglycoHc acid suture was introduced in 1970 with great success (21). This is because synthetic polymers are preferable to natural polymers since greater control over uniformity and mechanical properties are obtainable. The foreign body response to synthetic polymer absorption generally is quite predictable whereas catgut absorption is variable and usually produces a more intense inflammatory reaction (22). This greater tissue compatibihty is cmcial when the implant must serve as an inert, mechanical device prior to bioresorption. 

A careful use of solvent effects should be of great assistance in synthetic chemistry. For example, it may be predicted from the solvent effects described above that in the reaction of 2,4-dichloroquinohne with piperidine the a y ratio should increase in the less polar solvents, although the result might be obscured by the mutual influence of the two chlorine substituents. Nitro-activated benzenes support this prediction since ortho para ratios of 4.2 in methanol and 69 in benzene were observed in the reaction of 2,4-dichloronitrobenzene with piperidine. ... 

This sequence is presented by structural formulas in Scheme I, where the designations p + 2o + m, etc., refer to the number and position para, ortho, meta) of the activating ring-nitrogens relative to the leaving group (Le). The azinyls marked with a superscript a are in predicted locations. There is kinetic data available on those marked with a superscript b and synthetic organic comparisons on those marked with superscript c. ... 

It must be pointed out that the heterofuUerenes discussed above are not available today, and may never be available owing to synthetic limitations or unexpected instability not predicted in the above-mentioned theoretical studies. In comparison to carbon bucky balls, the chemistry of heterofuUerenes might have more important implications. Development of molecular engines and computers, derivatization for drug delivery, and applications in material science might be new scientific areas involving these interesting molecules. 

As a result, we could open the door to a new frontier in indole chemistry. Various 1-hydroxyindoles (4a), l-hydroxytryptophans(la), 1-hydroxytryptamines (lb), and their derivatives have been given birth for the first time. As predicted, 1-hydroxytryptophan and 1-hydroxytryptamine derivatives are found to undergo previously unknown nucleophilic substitution reactions. In addition, we have been uncovering many interesting reactivities characteristic of 1-hydroxyindole structures. From the synthetic point of view, useful building blocks for indole alkaloids, hither to inaccessible by the well-known electrophilic reactions in indole chemistry, have now become readily available. Many biologically interesting compounds have been prepared as well. 

The Diels-Alder reaction is of wide scope. Not all the atoms involved in ring formation have to be carbon atoms the hetero-Diels-Alder reaction involving one or more heteroatom centers can be used for the synthesis of six-membered heterocycles. The reverse of the Diels-Alder reaction—the retro-Diels-Alder reaction —also is of interest as a synthetic method. Moreover and most importantly the usefulness of the Diels-Alder reaction is based on its 5y -stereospecifi-city, with respect to the dienophile as well as the diene, and its predictable regio-and c ifo-selectivities. °... 

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