174020-37-2Relevant articles and documents
8-Polycycloalkyl-1,3-dipropylxanthines as potent and selective antagonists for A1-adenosine receptors
Shimada,Suzuki,Nonaka,Ishii
, p. 924 - 930 (2007/10/02)
With the aim of characterizing the hydrophobic interactions between xanthines and the A1 receptor site, 1,3-dipropyl-8-substituted xanthines were synthesized. Introduction of a quaternary carbon and the conformationally restricted cyclopentyl moiety into the 8-position of xanthines enhanced the adenosine A1 antagonism. 1,3-Dipropyl-8-(3- noradamantyl)xanthine (42) was identified to be a selective and the most potent A1 receptor antagonist reported to date. Under our structure-activity relationship, the 8-substituent of xanthine antagonists and the N6- substituent of adenosine agonists appears to bind to the same region of the A1 receptor.
Acid catalyzed ring contractions in endo-2,8-trimethylene-cis-bicyclo[3.3.0]octylcations to methylperhydrotriquinacenes. One of the methyl extrusion processes in the tricycloundecane rearrangement
Fujikura, Yoshiaki,Takaishi, Naotake,Inamoto, Yoshiaki
, p. 4465 - 4477 (2014/12/10)
Sulfuric acid catalyzed ring contractions with extrusion of a methyl group were examined for alcohol and olefin derivatives (28-31) of endo-2,8-trimethylene-cis-bicyclo[3.3.0]octane (11), which was one of the two possible progenitors, among altogether 69 isomers, for methylperhydrotriquinacenes (6, 7 and 12), the only methyltricyctodecane intermediates found so far, in the tricycloundecane rearrangement. Only minor amounts (1.6-2.0%) of methylperhydrotriquinacenes were formed from these reactants 28-31, and the results support the earlier theoretical conclusion that the methyl extrusions were in general energetically quite unfavorable processes owing to the formation of primary carbinyl cations at the expense of more stable secondary bridge or tertiary bridgehead ones. Reaction pathways for these precursors 28-31 were discussed with reference to those of perhydrotriquinacene 2-carbinyl cations (33a's), which corresponded to some of the ring contraction product cations from 28-31.
