7215-81-8Relevant academic research and scientific papers
Paracyclophanes: Extending the bridges. Synthesis
Pechlivanidis, Zissis,Hopf, Henning,Ernst, Ludger
experimental part, p. 223 - 237 (2009/06/21)
Preparatively satisfactory routes to [3.2]paracyclophane (10), [4.2]paracyclophane (14), [4.3]paracyclophane (19) as well as several derivatives of these compounds - among others the bromides 25, the ester 31, the diesters 40-43 - are described using well-established methods of cyclophane chemistry (ring-closure reactions leading to thiacyclophanes, ring contraction by sulfone pyrolysis). The parent systems and their derivatives are now available in gram quantities allowing a study of their chemical properties. Wiley-VCH Verlag GmbH & Co. KGaA, 2009.
Laser flash photolysis of [3,n]paracyclophan-2-ones. Direct observation and chemical behavior of 4,4′-(1,n-alkanediyl)bisbenzyl biradicals
Font-Sanchis, Enrique,Miranda, Miguel A.,Perez-Prieto, Julia,Scaiano
, p. 6131 - 6135 (2007/10/03)
The 4,4′-(1,n-alkanediyl)bisbenzyl biradicals (2b-d) have been generated from the Norrish type-I reaction of [3,n]paracyclophan-2-ones (1b-d) giving the paracyclophanes 3b-d as the only reaction products. The behavior of biradicals 2b-d has been studied in detail and compared with the previously reported biradical 2a. The lifetimes increase as the chain length decreases and are affected by the solvent viscosity, thus showing the effect of the length of the chain on the conformations of the biradicals. Quenching with persistent radicals such as TEMPO resulted in length-dependent rate constants. Finally, the study of the magnetic field effects on the biradical lifetimes suggest that ISC control determines biradical lifetimes for long-chain systems.
Hemicarcerands that encapsulate hydrocarbons with molecular weights greater than two hundred
Cram, Donald J.,Jaeger, Ralf,Deshayes, Kurt
, p. 10111 - 10116 (2007/10/02)
Syntheses are reported for the globe-shaped hemicarcerands 1 and 2 composed of two rigid bowl-like units (polar caps) attached to one another at their rims through four OCH2C≡CC≡CCH2O units (equatorial spacers). Eight pendant CH3(CH2)4 groups in 1 and C6H5CH2CH2 groups in 2 attached in assemblies of four to each polar cap render the hosts soluble in organic solvents. The important shell-closing reactions 2Ar(OCH2C≡CH)4 + [O] → Ar(OCH2C≡CC≡CCH2O)4Ar went in 5-8% yields in pyridine-O2-Cu(OAc)2 to give a hemicarcerand free of pyridine. The higher solubility of 1 (compared to that of 2) in organic solvents led to an examination of its binding properties. By heating 1 dissolved either in potential guests or in 1,3,5-[(CH3)3C]3C6H3 (too large to enter 1) containing dissolved potential guests at 80-140 °C for 2-7 days, 1:1 hemicarceplexes mixed with the empty host were isolated in those cases when the potential guests were just small enough to enter the host's portals at high temperatures but large enough not to depart during isolation as stable solids. Thus, constrictive bonding played a large role in kinetic stabilization of the hemicarceplexes. The 1H NMR spectra of both the host and the guest were markedly modified upon complexation. The half-lives in hours of representative complexes dissolved in CDCl3 at 25 °C were as follows: 1·1,3,5-[(CH3)2CH]3C6H 3, 1628; 1·1,3,5-Et3C6H3, 960; 1·4-Et[2.2]paracyclophane, 24; 1·1,3-dimethyladamantane, 13.5; 1-[3.3]paracyclophane, 13; 1·tetradehydro[2.2]paracyclophane, 11; 1·[2.2]paracyclophane, 5; 1·4,12-dihydroxy[2.2]paracyclophane, 4; and 1·[2.3]paracyclphane, 0.5. Complexes of smaller guests such as CHCl3, ferrocene, adamantane, and 1,3,5-trimethylbenzene were unstable to room-temperature isolation conditions. Larger guests such as [3.4]paracyclophane and 4,12-dinitro[2.2]paracyclophane did not enter the portals of 1 at temperatures under which host 1 was stable, whereas smaller guests such as CH2Cl2 and pyridine entered and departed the host at 25 °C rapidly on the NMR time scale. Catalytic reduction (H2, PdC) of the eight acetylenic bonds of 1 produced an empty host of much more flexible structure, 3, whose binding properties have not yet been examined.
Paracyclophane-10-enes and Paracyclophane-10,27-dienes: A Convenient Synthesis by the McMurry Reaction and Dynamic Stereochemistry
Gruetzmacher, Hans-Friedrich,Neumann, Ekkehard,Ebmeyer, Frank,Albrecht, Karsten,Schelenz, Peter
, p. 2291 - 2298 (2007/10/02)
The 1,3-bis(4-acylphenyl)propanes 2, 3, 9, 12, and 15 were subjected to a cyclization by reductive coupling with low-valent titanium (McMurry reaction). 2 and 3 are converted into the corresponding 10,11-dialkylparacyclophane-10-enes 4 and 5, respect
