Synthesis and Evaluation of 1-Arylsulfonyl-3-piperazinone Derivatives as Factor Xa Inhibitors V. A Series of New Derivatives Containing a Spiro[imidazo[1,2-a]pyrazine-2(3H),4'-piperidin]-5(1H)-one Scaffold

Pharmacological activity and mechanism of pyrazines

Heterocycles are common in the structure of drugs used clinically to deal with diseases. Such drugs usually contain nitrogen, oxygen and sulfur, which possess electron-accepting capacity and can form hydrogen bonds. These properties often bring enhanced target binding ability to these compounds when compared to alkanes. Pyrazine is a nitrogen-containing six-membered heterocyclic ring and many of its derivatives are identified as bioactive molecules. We review here the most active pyrazine compounds in terms of their structure, activity in vitro and in vivo (mainly antitumor activity) and the reported mechanisms of action. References have been downloaded through Web of Science, PubMed, Science Direct, Google Scholar and SciFinder Scholar. Publications reporting only the chemistry of pyrazine derivatives are beyond the scope of this review and have not been included. We found that compounds in which a pyrazine ring was fused into other heterocycles especially pyrrole or imidazole were the highly studied pyrazine derivatives, whose antineoplastic activity had been widely investigated. To the best of our knowledge, this is the first review of pyrazine derivatives and their bioactivity, especially their antitumor activity. This review should be useful for those engaged in development of medications based on heterocyclic compounds especially those based on pyrazine.

Novel factor Xa inhibitors: a patent review

IMPORTANCE OF THE FIELD

New oral anticoagulants with favorable safety profiles and fixed doses are required for the management of thromboembolism and stroke prevention in patients with atrial fibrillation. Among them, fXa inhibitors (the so-called xabans) are attractive options that can overcome limitations (e.g., bleeding) of the current oral antithrombotic therapy. The rational design of small-molecule direct fXa inhibitors, whose importance is testified by the growing number of publications and patents recently registered, has been fully supported by the X-ray crystallography of enzyme-ligand complexes.

AREAS COVERED IN THIS REVIEW

Pubmed, SciFinder Scholar, ISI web of knowledge(SM), http://ep.espacenet.com/ and Google websites were used as the main sources for literature retrieving, and > 100 patents filed between 2006 and April 2009, reviewed and discussed herein, highlight the variety among the P1 and P4 moieties on suitable scaffolds.

WHAT THE READER WILL GAIN

The replacement of the benzamidine P1 moiety, which characterizes the first generation, with less basic bioisosteric or nonpolar neutral P1 groups led to the disclosure of numerous fXa inhibitors with high potency, selectivity and oral bioavailability. Novel selective fXa inhibitors with stable pharmacokinetics, better therapeutic windows and ease-of-use than the existing anticoagulants are currently under advanced stage clinical trials.

TAKE-HOME MESSAGE

Available data from Phase II and Phase III studies reflect the drive towards fXa inhibitors as potentially more effective and safer antithrombotic drugs. Their development is expected to address two major needs for anticoagulation, namely safety and ease-of-use, and to significantly affect the anticoagulant market.

Synthesis and Evaluation of 1-Arylsulfonyl-3-piperazinone Derivatives as Factor Xa Inhibitors VI. A Series of New Derivatives Containing N,S- and N,SO2-Spiro Acetal Scaffolds

In the course of development of factor Xa (FXa) inhibitors, we have found unique compounds containing an N,O- and an N,N-spiro acetal structure. It appeared that the difference in overall conformation due to the N,X-spiro acetal structure might be important for FXa inhibitory activity. Therefore, other N,X-spiro acetal structures, an N,S- and an N,SO2-spiro acetal, were developed as analogues of the N,X-spiro acetal structure. Compound 7b (N,S-spiro acetal structure) was found to have the strongest activity in these series of N,X-spiro acetal compounds, which had ever been synthesized.(4,5)).