Inhibition of Nucleoside Transport by New Analogues of 4-Nitrobenzylthioinosine: Replacement of the Ribose Moiety by Substituted Benzyl Groups
摘要:
4-Nitrobenzylthioinosine (NBTI, 1) is a well-known inhibitor for the nucleoside transport protein ENT1. However, its highly polar nature is unfavorable for oral absorption and/or penetration into the CNS. In the search for compounds with lower polarity than NBTI we replaced its ribose moiety by substituted benzyl groups. Halogen, hydroxyl, (trifluoro)methyl(-oxy), nitro, and amine functionalities were among the substituents at the benzyl group. In general, substitution of the benzyl group resulted in a lower affinity for ENT1. Only 2-hydroxyl substitution showed a higher affinity. Most likely this is the result of hydrogen bonding. Substitution at the 2-position of the benzyl group with aryl groups was also addressed. Compared to parent compound carrying a 2-phenylbenzyl group, all synthesized analogues gave higher affinities. Introduction of fluoro, trifluoromethyl, methoxy, and hydroxyl groups at the phenyl group clearly showed that addition to the 4-position was preferable. Despite the highly different character of a ribose and a benzyl group, K-i values in the low nanomolar range were obtained for the benzyl-substituted derivatives. Compound 35, LUF5919, and compound 60, LUF5929, displayed the highest affinity (K-i = 39 nM for both compounds), having a polar surface area of 101 Angstrom(2) and 85 Angstrom(2), respectively.
A new and mild synthetic approach for the synthesis of 6-unsubstituted phenanthridine and phenanthridine-like compounds under metal-free conditions at room temperature has been developed. The strategy involved a tandem azide rearrangement/intramolecular annulation and oxidation reactions of biarylmethyl azide precursors to obtain the desired products in up to 99% yields with high regioselectivity.
Expedient Synthesis of Phenanthrenes via In(III)-Catalyzed 6-<i>Exo</i>-<i>Dig</i> Cycloisomerization
作者:Yongseok Kwon、Hyunkyung Cho、Sanghee Kim
DOI:10.1021/ol400073s
日期:2013.2.15
first example of In(III)-catalyzed selective 6-exo-dig hydroarylation of o-propargylbiaryls and their subsequent double-bond migration to obtain functionalized phenanthrenes. Electron-rich biaryl substrates undergo hydroarylation more effectively, and the substrates with various types of substituents on the alkyne can also be smoothly and selectively converted to phenanthrenes.