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Miscellaneous Cryptands

If a bridged bis-crown is used instead of diaza-18-crown-6, the cryptand contains two macrorings facing each other (see Table 8.5). Note also that the 2,2 -binaphthyl unit has been used extensively by Cram and his coworkers to provide chirality to mono-cyclic systems as well (see Sect. 3.13). [Pg.355]

A number of bi- or polycyclic structures have been prepared over the years which are somewhat difficult to classify within the narrow confines of crown and cryptand nomenclature. Nevertheless, these molecules deserve mention and are noted here. [Pg.355]

The similarity between the cryptands and the first of these molecules is obvious. Compound 7 7 is a urethane equivalent of [2.2.2]-cryptand. The synthesis of 7 7 was accomplished using a diacyl halide and l,10-diaza-18-crown-6 (shown in Eq. 8.13). Since amidic nitrogen inverts less rapidly than a tertiary amine nitrogen, Vogtle and his coworkers who prepared 7 7, analyzed the proton and carbon magnetic resonance spectra to discern differences in conformational preferences. Compound 7 7 was found to form a lithium perchlorate complex. [Pg.355]

The in-out bicyclic amines prepared by Simmons and Park bear a remarkable semblance to the cryptands but lack the binding sites in the bridges. As a result, these molecules interact with electrophiles in a fashion similar to other tertiary amines and generally do not exhibit strong interactions with alkali or alkaline earth metal ions. The in-out bicyclic amines are prepared by reaction of the appropriate acid chlorides and amines in two stages to yield the macrobicyclic amine after reduction of the amidic linkages. A typical amine is shown above as compound 18. [Pg.355]

A relative of the latter class of compounds are the macrotricyclic quaternary ammonium salts which have been reported by Schmidtchen. The bridges may contain either methylenes or ethyleneoxy units and the nitrogens are quaternarized. The underlying principle is to provide a cavity suitable for solvating or at least trapping anions. Schmidtchen presents evidence which suggests the formation of halide inclusion complexes. The synthesis of these molecules is accomplished along more or less traditional lines Such a species is illustrated above as compound 19. [Pg.356]


Miscellaneous molecules involving crown ethers, cryptands and related moieties... [Pg.177]

Miscellaneous Methods of Preparing Phosphines. - The synthesis and properties of phosphorus-containing cryptand ligands has been reviewed. The basic principles for the synthesis of functionalised phosphorus-containing heterocyclic systems have been summarised, relating to the chemistry of phosphabicyclohexanes, dihydrophosphinines, phosphabicyclooctadienes, and phosphabicyclooctenes °. Ethylene acetals (108) of the 9-oxa-2-phosphabicyclo[4.4.0]-5-one system have been prepared. Methods for the... [Pg.12]

Miscellaneous macrobicyclic ligands. Numerous other types of macrobicyclic cryptands have been synthesized in recent years, including ferrocene cryptands... [Pg.39]


See other pages where Miscellaneous Cryptands is mentioned: [Pg.355]    [Pg.355]    [Pg.40]    [Pg.355]    [Pg.355]    [Pg.40]   


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Cryptands 2.1.1 [cryptand

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