A general approach toward the synthesis of C-nucleoside pyrazolo[1,5-a]-1,3,5-triazines and their 3',5'-bisphosphate C-nucleotide analogues as the first reported in vivo stable P2Y(1)-receptor antagonists

J Org Chem. 2002 Nov 15;67(23):8063-71. doi: 10.1021/jo026268l.

Abstract

In our effort to identify potent purinergic P2Y(1) receptor antagonists as potent platelet aggregation inhibitors with enhanced metabolic stability, we developed an efficient route for the large-scale preparation of 2'-deoxy-C-nucleosides of pyrazolo[1,5-a]-1,3,5-triazine. The key strategic elements of this novel synthetic approach involved the following: (i) the use of a novel activating group, the N-methyl-N-phenylamino group, which was easily generated in high yield by treatment of the pyrazolo[1,5-a]-1,3,5-triazin-4-one (5) with phosphorus oxychloride and dimethylaniline under high pressure, (ii) a regio- and stereospecific palladium-mediated coupling reaction of the readily available unprotected glycal 1,4-anhydro-2-deoxy-D-erythro-pent-1-enitol (4b) and the 8-iodo derivative (16), and (iii) the stereoselective reduction of the ketone group of the furanosyl ring followed by the subsequent displacement of the N-methyl-N-phenylamino group upon treatment with methylamine. The beta configuration at the anomeric C-1' position of the glycal moieties was perfectly retained throughout this conversion. This procedure afforded 8-(2'-deoxy-beta-D-ribofuranosyl)-2-methyl-4-(N-methylamino)pyrazolo[1,5-a]-1,3,5-triazine (21) and 8-(2'-deoxy-beta-D-xylofuranosyl)-2-methyl-4-(N-methylamino)pyrazolo[1,5-a]-1,3,5-triazine (24) with an overall yield of 50% and 39%, respectively. Finally, the conversion of nucleosides 21 and 24 to the pyrazolotriazine C-nucleotides 3',5'-bisphosphate 2 and 3',5'-cyclophosphate 26 is also described herein and represents the first reported nucleotide derivatives within the pyrazolo[1,5-a]-1,3,5-triazine series. Preliminary biological testing has shown that compound 2 strongly inhibits ADP-induced human platelet aggregation and shape change and possesses significant efficacies 30 min after injection in rat, highlighting a strong P2Y(1)-receptor antagonist activity in vitro combined with a prolonged duration of action in vivo.

MeSH terms

  • Adenosine Diphosphate / pharmacology
  • Animals
  • Blood Platelets / drug effects
  • Humans
  • Nucleosides / administration & dosage
  • Nucleosides / chemical synthesis*
  • Nucleosides / pharmacology
  • Nucleotides / administration & dosage
  • Nucleotides / chemical synthesis*
  • Nucleotides / pharmacology
  • Phosphatidic Acids
  • Platelet Activation / drug effects
  • Platelet Aggregation Inhibitors / administration & dosage
  • Platelet Aggregation Inhibitors / chemical synthesis
  • Platelet Aggregation Inhibitors / pharmacology
  • Purinergic P2 Receptor Antagonists*
  • Rats
  • Receptors, Purinergic P2Y1
  • Triazines / administration & dosage
  • Triazines / chemical synthesis
  • Triazines / pharmacology

Substances

  • Nucleosides
  • Nucleotides
  • P2RY1 protein, human
  • P2ry1 protein, rat
  • Phosphatidic Acids
  • Platelet Aggregation Inhibitors
  • Purinergic P2 Receptor Antagonists
  • Receptors, Purinergic P2Y1
  • Triazines
  • bisphosphatidic acid
  • Adenosine Diphosphate