Crown-4-compounds

Cooper, S. R. 1992, Crown Compounds. Toward Future Applications, VCH Verlag Weinheim, Ger. 

S. R. Cooper, ed.. Crown Compounds TowardEuture Applications, VCH, Weinhekn, 1992. 

Fig. 3. Crown compounds/cryptands and analogous inclusion hosts. (1 4) Crown macro rings bicyclic cryptands (5) [37095-49-17, (6) [31250-06-3J, (7) [31364-42-8] (8) [23978-09-8]-, (9) spherical cryptand [56698-26-1]-, (10) cylindrical cryptand [42133-16-4]-, (11) apodand [57310-75-5]-, and (12) a spherand...

Fig. 4. Chiroselective inclusion formation of racemic l-phenylethylammonium salt ((R/S)-14) using optically active crown compound ((i, 5)-13) [53955-48-9]. The diastereomeric inclusion complex (R)-(14) is more stable than (3, 3)-(13)-(3)-(14) (top views, dotted lines represent hydrogen...

Crown compounds containing a single 2,2 -binaphthyl subunit.116... 

Crown compounds having a spiro-3,3-oxetane subunit in the macroring. . 132... 

Crown compounds containing pyridyl or bipyridyl subunits.141... 

Table 3.20. Crown compounds containing two 2,2 -binaphthyl subunits...

Table 3.23. Crown compounds containing the furan subunit...

Table 3.27. Crown compounds containing two macrocyclic rings ...

Although the polysulfur macrocycles became more interesting to the scientific community after Pedersen s report of the crown compounds (see Chap. 1), examples of such structures may be found in the literature dating back some time. The first report of a macrocyclic polysulfide appears to be that by Ray who found in 1920 that when 1,2-dimercaptoethane and 1,2-dibromoethane were heated with alcoholic potassium hydrogen sulfide as shown in Eq. (6.2), triethylene trisulfide (2) and a substance presumed to be triethylene tetrasulfide (3) could be isolated. 

There are quite a number of crown compounds known which contain a thiophene or other sulfur-containing subunit. The reader is directed to the tables at the end of each chapter in order to locate these species. Because of the expense of including each structure under each possible category, some sulfur-containing compounds may not be listed in this chapter. It is hoped that the tables are well enough organized that the desired compound can be located if it is known by considering other structural features. 

There are, however, some crown type compounds which contain no structural feature except the thiophene subunit, and these deserve some comment here. This is especially true since one of these compounds was prepared very early in the history of crown compounds. Ahmed and Meth-Cohn were interested in sulfur analogs of the porphyrin ring system and prepared compound 7 in 1969 by the method shown in Eq. 

Examples of silicon-containing macrocycles are rare and are perhaps incidental to the report of crown-type compounds. Obviously, silicon is more like carbon than a heteroatom in its ability to complex a cation. Nevertheless, there is a recent report of a crown compound which contains silicon as part of the macroring. Liptuga, Irodionova... 

Hiraoka, M, (ed.) Crown Compounds — Properties and Application (in Japanese), Kodansha Scientific 1978... 

Tabushi, I. Yamamura, K. Water Soluble Cyclophanes as Hosts and Catalysts, 113,145-182 (1983). Takagi, M., and Ueno, K. Crown Compounds as Alkali and Alkaline Earth Metal Ion Selective Chromogenic Reagents. 121, 39-65 (1984). 

The solvent extraction of metal ions by crown compounds. Y. Takeda, Top. Curr. Chem., 1984,... 

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