Triple layer cyclophanes

By using a similar method, we can prove that the cell complexes of the molecules [m [n]paracyclophane [22] and triple layered cyclophane [23] are also intrinsically chiral. Figure 30 illustrates these molecules... 

Cyclic Voltammetry and Reduction of Triple-Layered Cyclophane Complexes... 

Triple-layered cyclophanes 262 can be synthesized according to Scheme 70 [77CL977 93JCS(P2)1373] or Scheme 73 [93JCS(P2)703], where one (4n 2)n system in starting material 258 or 265 is already a cyclophane,... 

Cyclophane ruthenium complexes have been prepared by the methods developed to make arene ruthenium complexes (Section II,A). Treatment of the solvated complexes of type 7, obtained from the dimers 1 and silver tetrafluoroborate in acetone, with 1 equiv of cyclophanes a-j in the presence of trifluoroacetic acid gives the double-layered (i76-arene)-(i76-cyclophane)ruthenium(II) complexes 263 in good yield (Scheme 26, p. 222). When 7 is used in excess, the triple-layered complex 264 is formed (159-162). 

Triple-layered [2.2]metacyclophanoarenes (44) were also prepared and their enantiomers were enriched by chiral HPLC (on a Daicel OT(+) column). The CD spectra were compared with those of the corresponding two-layered cyclophanes (e.g., 25,26). The major Cotton effect peaks of 44 in the spectra were red-shifted by 20-30 nm, and some additional, but weak, Cotton effects were observed [40]. 

The triple layered tetraazacyclophane (46) consisting of the unique crossed meta-meta cyclophane linkage was prepared and the enantiomers were separated by chiral HPLC (on a Daicel OD column). The CD spectrum of 46 was rather complex and seven Cotton effect peaks in the 190-280 nm region were observed [56]. Unfortunately, the four tosyl groups and the ester functions prevented the reasonable theoretical discussion and the assignment of absolute configuration. 

Harren J, Sobanski A, Nieger M, Yamamoto C, Okamoto Y, Vogtle F (1998) A triple layered helical chiral cyclophane - one-pot synthesis, enantiomer separation and chiroptical properties. Tetrahedron Asymmetry 9 1369-1375... 

The two benzene rings in compounds like 8 lie on top of each other and thereby exhibit interesting electronic and spectroscopic interactions. Misumi [40] was successful in preparing multilayered cyclophanes with up to six benzene decks. Nowadays the mono- and bis(tricarbonylchromium) complexes 35a and 35b of the triple layered (35) as well as 36a and 36b of the quadruple layered para-cyclophane (36) are known (Fig 6c) [29],... 

From the archival measured enthalpy of formation of the cyclophane, 409.5 4.4 kJ/mol, the enthalpy of reaction is 3.9 5.8 kJ/mol, statistically thermoneutral. It appears that triple layering has but little effect beyond that of the two double-layering para-cyclophanes found therein. 

Optically active triple-, quadruple-, quintuple-, and sextuple-layered [2.2]para-cyclophanes (40-43) were prepared and their CD spectra were reported [54]. The CD spectra of these multilayered [2.2]paracyclophanes were more complex than those of [2.2]paracyclophanes, exhibiting three bands of the same sign centered at ca. 270, 310, and 350 nm. The observed fine structures were ascribed to the face-to-face interactions between the distorted benzene rings. 

---