Chiral cryptands

Lehn and his coworkers have prepared a number of chiral cryptands based upon the 2,2 -binaphthyl unit . In a typical preparation, the binaphthyl units are treated with bromoacetic acid to form the phenoxyacetic acid derivatives which are then converted into the corresponding diacyl chlorides (75). Reaction of 15 with l,10-diaza-18- 

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High pressure synthesis of cryptands ana complexing behaviour of chiral cryptands. J. Jurczak and M. Pietraszkiewicz, Top. Curr. Chem., 1986,130,183 (49). 

Jurczak, J., and Pietraszkiewicz, M. High-Pressure Synthesis of Cryptands and Complexing Behaviour of Chiral Cryptands. 130, 183-204 (1985). 

High-Pressure Synthesis of Cryptands and Complexing Behaviour of Chiral Cryptands... 

Synthesis of Chiral Cryptands Incorporating Carbohydrate Units. . . 197... 

Complexing Properties of Chiral Cryptands Incorporating the Binaphthyl... 

In order to avoid an overloading, this review is limited to bicyclic cryptands possessing nitrogen atoms in bridge-head fashion. A more detailed discussion, concerning the complexing behaviour of chiral cryptands will be given in the end of this article. 

Subsequent reaction with lithium aluminium hydride afforded the chiral cryptand 10 in only 15 % yield 43. However, LiAlH4 could not be replaced by a more powerful agent, like diborane which will cleave the acetal group. 

Mixtures of the four mentioned chiral diazacoronands with bis(2-iodoethyl) ether in ca. 0.08 M solution in acetone were exposed to the pressure of 8 kbar for 20 h at ambient temperature. In all cases the quaternary salts were obtained in quantitative yield as colourless precipitates. Demethylation was followed in the usual manner to give the chiral cryptands 10, 11, 12, and 13 in very good yields 87, 72, 82, and 79, respectively. 

In conclusion, the design, the synthesis, and the complexation properties of chiral cryptands are still open areas for the creativity of chemists. 

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