The String Synthesis

There are different possibilities for practical realization of the principles and the string synthesis described below represents only one of them. 

The support units used in the string synthesis were Chiron Mimotopes Crowns shown in Fig. 1. They were used together with different color stems, also purchased from Chiron Mimotopes. Spatially ordered groups are formed with the crowns (Fig. 1A) by stringing them together with a thread. The stems serve to string the crowns together and to facilitate redistribution. The stems were modified as shown in Fig. 1. 

The software for the string synthesis technique is written in visual basic and the data appear in Microsoft Excel sheets. This software can be downloaded via the Internet from http //szerves.chem.elte.hu/furka by clicking on the title ExcelBook appearing on the lower part of the main page. This software is compatible with only those PC systems that have Excel installed. 

In this case, the products formed in the support units can be identified by computer prediction, based on the relative positions of the units occupied in the final groups. There are different possibilities for practical realization of the principles. In the string synthesis described below, the relative spatial arrangement of the units is maintained by stringing them. 

A Furka, JW Christensen, E Healy, HR Tanner, H Saneii. The string synthesis. A spatially addressable split procedure. J. Comb. Chem. 2 220-223, 2000. 

Any combinatorial synthetic method carried out with macroscopic solid support units, even if coding is omitted, has to ensure that the route of every unit in the entire multistep synthetic process can be traced. In string synthesis this can be achieved by... 

The string itself must be resistant to solvents and other reaction conditions involved in the synthesis. In the illustrated example, a polyethylene fishing line was used. The stringed crowns are shown in Fig. 2. 

Lu, J. Evidence for the string-bag structure as a basic structural unit for the active center of nitrogenase and an attempted synthesis of string-bag model compounds, in Ref. 23, p. 50... 

Since 1980, siloxane-urea block copolymers prepared by the reaction of bisaminoalkyl-terminated silicones and diisocyanates [1] have been well known in the literature. Silicone is responsible for the elastomeric behavior and urea for the thermal behavior. Nevertheless, to obtain high-molecular-weights in the polymerization of such copolymers, the string compounds have to be sufficiently pure [2]. Therefore, one key step in the synthesis of such block copolymers is the preparation of... 

In the genetic synthesis of the binary string representing the cut order plan, two possible kinds of encoding methods are considered due to search space discrepancy. 

The knot can also be prepared using a stepwise synthesis, which helps to determine the route by which it is formed in the one-step reaction. The string-like molecule 14 (Figure 13) was prepared in order to ascertain whether indeed it is an intermediate on the pathway to knot 13. Indeed, reaction of this open knot with di-acid chloride 9 generates the knot 13 in 11% yield. Clearly, the possibility of using the open knot as a reagent with different di-acid chlorides is possible, and leads to a variety of substituted knot molecules. ... 

String literals can generally only be used in synthesis if each character of the string represents a discrete enumeration literal and hence a single bit encoded value. Hence, an array of type BCX)LEAN could be formed using aggregates but not strings as illustrated below. 

The reactions of this class are little different conceptually from those of Section 5.03.1.2. A string of individual conversions leads to a net [2 + ] synthesis of heterocycles, such as in Scheme 12. 

The synthesis of [3]- (figuratively shown as 7) and a [5]rotaxane (8) with one central and two terminal porphyrins in the open configuration has been reported <96AG(E)906> also a rotaxane with two Ru(terpy>2 stoppers has appeared <96CC1915>. A pseudorotaxane comprised of a macroring of 2,9-diphenyl-1,10-phenanthroline unit and a molecular string... 

In order to begin practicing synthesis problems, it is absolutely essential that you master all of the individual reactions that we have seen so far. You must learn how to walk before you can start to run. Therefore, we will first focus on one-step synthesis problems. Once you feel comfortable with the individual reactions, then we can start stringing them together in various sequences to form synthesis problems. 

Covalent attachment of adamantane molecules is a key strategy to string them together and construct molecular rods. The McMurry coupling reaction was employed to obtain polyadamantane molecular rods (see Fig. 35) [170]. As another example, synthesis of tetrameric 1,3-adamantane and its butyl derivative has been reported [171] (see Fig. 36). 

---