LEHN Cryptand synthesis

Polyaza macrobicyclic cryptands synthesis, crystal structures of a cyclophane type macrobicyclic cryptand and of its dinuclear copper(I) cryptate, and anion binding features, J. Jazwinski, J.-M. Lehn, D. Lilienbaum, R. Ziessel, J. Guilhem and... 

A number of bridged crown ethers have been prepared. Although the Simmons-Park in-out bicyclic amines (see Sect. 1.3.3) are the prototype, Lehn s cryptands (see Chap. 8) are probably better known. Intermediates between the cryptands (which Pedersen referred to as lanterns ) and the simple monoazacrowns are monoazacrowns bridged by a single hydrocarbon strand. Pedersen reports the synthesis of such a structure (see 7, below) which he referred to as a clam compound for the obvious reason . Although Pedersen appears not to have explored the binding properties of his clam in any detail, he did attempt to complex Na and Cs ions. A 0.0001 molar solution of the clam compound is prepared in ethanol. The metal ions Na and Cs are added to the clam-ethanol solutions as salts. Ultraviolet spectra of these solutions indicate that a small amount of the Na is complexed by the clam compound but none of the Cs . 

Although Lehn and his coworkers prepared a large number of cryptands and derived complexes over the years, the synthetic approach to these compounds remained essentially similar for most of them. Details are presented for a number of such compounds in ref. 26. The essential features of these syntheses were use of amide-forming reactions in the absence of templating ions with reliance on a high dilution step to form the second ring. An alternative approach for the synthesis of cryptands was developed by Dye and his coworkers. Their approach involved the use of a flow synthesis to replace the high dilution step. 

Shortly after their first report of all-oxygen bridged cryptands, Dietrich, Lehn and Sauvage reported incorporation of sulfur in the strands. The experimental methods used were essentially similar to those applied in the syntheses of the parent cryptands. As in previous cases, a diacyl chloride was condensed with a diamine under high dilution conditions. In this case, however, the diamine contained sulfur atoms rather than oxygen. The synthesis of compound 5 was accomplished in two stages as illustrated below in Eq. (8.3). The first cyclization step affords the macrocyclic amine in 55% yield. The macrobicyclic product (5) is formed in 25% yield from the monocyclic diamine and the acid chloride. 

Synthesis of cryptands which contain nitrogen atoms in the bridges has also attracted Lehn s attention. In general, a similar synthetic strategy was utilized, but ni-... 

A typical synthesis. The preparation of (213 m, n = 1) serves to illustrate the general synthetic strategy used to obtain this class of polyether cage. Starting from diaza-18-crown-6 and the required diacid chloride, condensation followed by reduction yields the corresponding cryptand, 2.2.2 (Dietrich, Lehn Sauvage, 1970 Dietrich, Lehn, Sauvage Blanzat, 1973)-see [4.8],... 

J. P. Konopelski, F. Kotzyba-Hibert, J.-M. Lehn, J.-P. Desvergne, F. Fages, A. Castellan, and H. Bouas-Laurent, Synthesis, cation binding, and photophysical properties of macrobicyclic an-thraceno-cryptands,./. Chem. Soc., Chem. Commun. 433 (1985). 

Jean-Marie Lehn synthesis of the first cryptands... 

Dietrich, B. Lehn, J.-M. Guilhem, J. Pascard, C. Anion receptor molecules synthesis of an octaaza-cryptand and structure of its fluoride cryptate, Tetrahedron Lett. 1989, 30, 4125-4128. 

The most significant contribution into progress of cryptand chemistry is associated with Lehn s research group in Strasbourg. The first report on the synthesis of a [2.2.2]cryptand appeared in 1969 21). This synthesis is presented in Scheme 1. Scheme 1... 

The diaza-crowns are important because they are key intermediates in the synthesis of cryptands and other -substituted ligands (Dietrich et al., 1969, 1973 Lehn, 1973, 1978). The diaza-crowns also have complexing properties that are similar to those of certain biological compounds (Hosseini et al.,... 

Park and Simmonds Katapinand anion hosts 1969 — Jean-Marie Lehn Synthesis of the first cryptands... 

In a seminal paper appearing in 1969, Dietrich, Lehn, and Sauvage" described the first synthesis of a series of cryptands of the type 14. In part, it was the known alkali metal binding (and membrane transport behavior) of the natural antibiotic ionophores that provided the inspiration for the design of these then novel cage systems." ... 

The discovery of crown ethers by Pedersen was rapidly followed by the report by Lehn and coworkers of the preparation of the A,iV -diazamacrobicy-clicpolyethers (cryptands) in 1969 (Fig. 13.8) [84]. Although the synthesis of a diazabicyclic katapinand by Park and Simmons in 1968 [85,86] is considered to be the first cryptand, the actual word cryptand was introduced by Lehn in 1969 to describe bicyclic ligands [87]. 

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