Atropisomeric (R,R)-2,2'-Bi([2]paracyclo[2](5,8)quinolinophane) and (R,R)-1,1'-Bi([2]paracyclo[2](5,8)isoquinolinophane): synthesis, structural analysis, and chiroptical properties |
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Authors: | Ricci Giacomo Ruzziconi Renzo Giorgio Egidio |
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Institution: | Dipartimento di Chimica, Università di Perugia, via Elce di Sotto, 8 06123 Perugia, Italy. |
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Abstract: | Atropisomeric (R,R)-2,2'-bi(2]paracyclo2](5,8)quinolinophane) (R,R)-1] and (R,R)-1,1'-bi(2]paracyclo2](5,8)isoquinolinophane) (R,R)-2] have been prepared in moderate overall yield (17 and 9%, respectively) by a four-step sequence starting from (R)-(-)-4-amino2.2]paracyclophane and (R)-(-)-4-carboxy2.2]paracyclophane, respectively. The structures have been determined on the basis of NOE (1)H NMR analysis and molecular mechanics (MM) calculations performed with a Spartan02 program, using the MMF94s force field. A preliminary, qualitative analysis of the chiroptical properties of these two compounds has also been attempted. The main spectral data can be interpreted in terms of an almost planar 2,2'-bisquinoline chromophore inserted in a paracyclophane structure in the case of (R,R)-1, while in the case of (R,R)-2, the main role is played by a distorted 1,1'-bisisoquinoline chromophore. On the basis of the above structural results, a hypothesis about the enantioselection capability of these two molecules has also been formulated. |
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