The Significance of 2-Furyl Ring Substitution with a 2-(para-substituted) Aryl Group in a New Series of Pyrazolo-triazolo-pyrimidines as Potent and Highly Selective hA3 Adenosine Receptors Antagonists: New Insights into Structure−Affinity Relationship and Receptor−Antagonist Recognition
摘要:
Among the heterocyclic structures identified as potent human A(3) (hA(3)) adenosine receptor's antagonists, we have demonstrated that the new pyrazolo-triazolo-pyrimidines, bearing an aryl group in replacement of the C-2-furyl ring, not only confer a good pharmacological profile (with significantly enhanced selectivity against other adenosine receptor subytpes) but also overcome the metabolic transformation of the furan ring into toxic intermediates. All the synthesized [2-(para-substituted) phenyl]-pyrazolo-triazolo-pyrimidines showed affinity at the hA(3) receptor in the low nanomolar range. The most potent derivative of the series presented better affinity and excellent selectivity (compound 31, K-i hA(3) = 0.108 nM; hA(1)/hA(3) = 5200; hA(2A)/hA(3) = 7200), in comparison to the C-2-furyl counterpart. A receptor-driven molecular modeling investigation, based on a recently proposed model of A(3) receptor derived from the crystallographic structure of human A(2A) receptor, has been carried out in order to support the experimental binding data and to justify the enhanced selectivity against the other receptor subtypes.
The Significance of 2-Furyl Ring Substitution with a 2-(para-substituted) Aryl Group in a New Series of Pyrazolo-triazolo-pyrimidines as Potent and Highly Selective hA3 Adenosine Receptors Antagonists: New Insights into Structure−Affinity Relationship and Receptor−Antagonist Recognition
摘要:
Among the heterocyclic structures identified as potent human A(3) (hA(3)) adenosine receptor's antagonists, we have demonstrated that the new pyrazolo-triazolo-pyrimidines, bearing an aryl group in replacement of the C-2-furyl ring, not only confer a good pharmacological profile (with significantly enhanced selectivity against other adenosine receptor subytpes) but also overcome the metabolic transformation of the furan ring into toxic intermediates. All the synthesized [2-(para-substituted) phenyl]-pyrazolo-triazolo-pyrimidines showed affinity at the hA(3) receptor in the low nanomolar range. The most potent derivative of the series presented better affinity and excellent selectivity (compound 31, K-i hA(3) = 0.108 nM; hA(1)/hA(3) = 5200; hA(2A)/hA(3) = 7200), in comparison to the C-2-furyl counterpart. A receptor-driven molecular modeling investigation, based on a recently proposed model of A(3) receptor derived from the crystallographic structure of human A(2A) receptor, has been carried out in order to support the experimental binding data and to justify the enhanced selectivity against the other receptor subtypes.
A new synthesis of 2,8-disubstituted pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines
作者:Anton V. Dolzhenko、Giorgia Pastorin、Anna V. Dolzhenko、Wai Keung Chui
DOI:10.1016/j.tetlet.2009.07.113
日期:2009.10
5-c]pyrimidines, which are key intermediates in the preparation of adenosine receptor antagonists, is developed. The method allows introduction of a variety of aryl substituents at position 2 of the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine system via cyclocondensation of 5-amino-4-iminopyrazolo[3,4-d]pyrimidine with benzaldehydes accompanied with oxidation by iodobenzene diacetate. Some unexpected
开发了实用的吡唑并[4,3- e ] [1,2,4]三唑并[1,5- c ]嘧啶的合成方法,它们是制备腺苷受体拮抗剂的关键中间体。该方法允许通过5-氨基-4-亚氨基吡唑并环缩合在吡唑并[4,3- e ] [1,2,4]三唑并[1,5- c ]嘧啶体系的2位引入各种芳基取代基。[3,4- d ]嘧啶与苯甲醛并伴随有碘代二苯乙酸酯的氧化。观察到一些意想不到的反应,并使用NMR光谱和X射线晶体学证实了产物的结构。