38059-08-4Relevant academic research and scientific papers
The first efficient synthesis and optical resolution of monosubstituted cyclotribenzylenes
Schmuck, Carsten,Wienand, Wolfgang
, p. 655 - 663 (2007/10/03)
A new and high yielding synthetic route to monosubstituted cyclotribenzylenes 6 via the cyclocondensation of benzene with a suitably monosubstituted diol 20, obtained from ozonolysis of the corresponding dibenzosuberene precursor 19, was developed for the first time! The dibenzosuberene itself could be readily prepared in large quantities from inexpensive starting materials in five steps. Using this synthetic approach, a mono bromosubstituted cyclotribenzylene 12a was synthesized on large scale. Another four monosubstituted cyclotribenzylenes 21-24 were also prepared either via bromine/lithium exchange followed by subsequent quenching with external electrophiles or a copper mediated reaction with cyanide. These molecules adopt a rigid crown conformation as shown by X-ray analysis and temperature dependent NMR studies. The barrier to inversion is quite high, requiring temperatures well above 120°C before inversion takes place. Futhermore, such monosubstituted cyclotribenzylenes are planar chiral and after optical resolution, using HPLC, we were able to obtain the first planar chiral Cl-symmetric cyclotribenzylenes in form of the optically pure enantiomers of 12a, the CD spectra of which are exact mirror images over the entire spectral range.
Orthocyclophanes. 1. Synthesis and Charaterization of 4>- and 5>Orthocyclophanes and Bicyclic Biscyclophanes
Lee, Woo Young,Park, Chang Hee,Kim, Young Dong
, p. 4074 - 4079 (2007/10/02)
4>- and 5>orthocyclophanes have been designed, synthesized and characterized.Dimetalation of bis(2-bromophenyl)methane (14) to the corresponding dilithio reagent 21, followed by reaction with aromatic dialdehydes bis(2-formylphen
Organic Reactions Catalyzed by Solid Superacids. 9. Friedel-Crafts Cyclobenzylation of Benzene with Bis-(hydroxymethyl)diarylalkanes Catalyzed by a Perfluorinated Sulfonic Acid Resin (Nafion-H)
Yamato, Takehiko,Sakaue, Naozumi,Furusawa, Takashi,Tashiro, Masahi,Prakash, G.K.Surya,Olah, George A.
, p. 2414 - 2438 (2007/10/02)
Cyclobenzylation of benzene using bis(hydroxymethyl)diarylmethanes (6) and bis(hydroxymethyl)diarylaethanes (14) in the presence of solid perfluorinated sulfonic acid resin, Nafion-H, as a catalyst results in novel bridged aromatic compounds, 10,15-dihydro-5H-tribenzocyclononenes (15) and metacyclophanes (17), respectively.The reactions were clean, and water that was formed as a by-product did not deactivate the catalyst.It was also found that cyclobenzylation products, methacyclophanes were not formed via the isomerization of the corresponding orthomethacyclophane (19) under the reaction conditions used.The posible mechanism of the reaction is also discussed.
STUDIES ON THE SYNTHESIS OF HETEROCYCLIC COMPOUNDS. XVII. THE PREPARATION OF MACROCYCLIC POLYESTER LIGANDS CONTAINING THE 2,2'-BIS(HYDROXYMETHYL)DIPHENYLMETHANE SUBCYCLIC UNIT
Corda, Luciana,Fadda, Anna Maria,Maccioni, Anna Maria,Maccioni, Antonio,Podda, Gianni
, p. 671 - 676 (2007/10/02)
Novel macrocyclic tetraester ligands containing the 2,2'-bid(hydroxymethyl)diphenylmethane subcyclic unit have been prepared using an intermediate dioxastannocin with diacyl chlorides.The products were characterized by analitycal and spectroscopic (IR and NMR) data.The MS spectra of these ligands have been studied and the fragmentation patterns and structures of the main ions are described.
