A Three‐Blade Propeller Compound with Seven Bracketed Benzene Rings

Abstract

Fluorescence spectroscopy measurements give a value of pK=2.35 in water for the complex formation of 2 with 8anilino-1-naphthalenesulfonic acid (ANS). This is higher than the value for the P-cyclodextrin.ANS complex in neutral aqueous solution.,The ease with which the new host system 2 can be structurally varied is shown by the successful synthesis in an analogous way of the 32-membered host compounds 8 and 9, derived from o-terphenyl, as well as of the 16-membered "monomers" 10 and 11, respectivelyL6]. 8 : R=C02Et 9: R:C02H 10: RzC02Et 11: R=C02HCarbomacrocycles as host compounds have the advantage that their large ring cannot be hydrolytically cleaved. This is especially important if functional groups other than the carboxy group are attached to the large ring in order to effect host reactions that are analogous to enzymatic reactions".''. Accordingly, compounds of the types 1 and 8 can be derivatized under harsh conditions, e.g., to give uncharged, but nonetheless water-soluble, host compounds with oligoamide, urea, or barbiturate side chains. Oligocarboxylic acids of the types 2 and 9 are, moreover, also (acid) complex formers for cations. If the carboxy groups point inward, a smaller cavity is formed, which is more suitable for metal cations. CAS Registry numbers:Angew Chem. In!. Ed. Enql. 24 (1965) No. 3 0 V C H Veriugsgesellschuft mbH. 0-6940 Weinheim 1985 0570-0833/95/0303-0223 S 02.50/0

Efficient Separation of Enantiomers Using Stereoregular Chiral Polymers

“…A typical advantage of the CSP is its high resolution power for stereochemically interesting compounds, which are difficult to be separated by other methods (Figure ). ,− With such a high chiral recognition ability, the PTrMA-based CSP has been commercialized from Daicel with the trade name of Chiralpak OT­(+) . However, the solvents that can be used for the PTrMA-coated CSP are very limited, and the use of many polar solvents will lead to serious damage of the packed column by dissolving the polymer inside.…”