Cyclizations of Alkenyl(Alkynyl)-Functionalized Quinazolinones and their Heteroanalogues: A Powerful Strategy for the Construction of Polyheterocyclic Structures

Quinazolin-4-one, its heteroanalogues, and derivatives represent an outstandingly important class of compounds in modern organic, medicinal, and pharmaceutical chemistry, as these molecular structures are noted for their wide synthetic and pharmacological potential. In the last years, ever-increasing research attention has been paid to quinazolinone derivatives bearing alkenyl and alkynyl substituents on the pyrimidinone nucleus. The original structural combination of synthetically powerful endocyclic amidine (or amidine-related) and exocyclic unsaturated moieties provides a driving force for cyclizations, which offer an efficient toolkit to construct a variety of fused pyrimidine systems with saturated N- and N,S-heterocycles. In this connection, the present review article is mainly aimed at systematic coverage of the progress in using alkenyl(alkynyl)quinazolinones and their heteroanalogues as convenient bifunctional substrates for regioselective annulation of small- and medium-sized heterocyclic nuclei. Much attention is paid to elucidating the structural and electronic effects of reagents on the regio- and stereoselectivity of the cyclizations as well as to clarifying the relevant reaction mechanisms.

Recent Advances in the Synthesis of Xanthines: A Short Review

Xanthine and its derivatives are considered a pharmacologically potential moiety that manifests immense biological activities. Owing to this much diversity in the biological field, this scaffold has fascinated the attention of many researchers around the globe to scrutinize its basic structure chemically as well as biologically. In recent years, xanthine derivatives have been used therapeutically in different pathological conditions due to their presence in day-to-day life. Herein, we review the recent progress in the synthesis of xanthine and its derivatives. Some of the widely used synthetic strategies such as (a) Traube's synthesis, (b) one-pot synthesis, (c) xanthine-anneleated synthesis, and (d) miscellaneous synthesis were compiled in this review paper. The results obtained from this review paper highlight the significance of various xanthine derivatives as possible leads to the development of new drugs. The data compiled in this review paper could help the medicinal chemist in designing new active compounds from the modification of the already existing compounds in the search for novel drug leads. This report concludes that the various synthetic procedures exemplified in this review paper may serve as a support system for the designing of new molecules with a xanthine scaffold. Thus, we hope that this molecule may serve as the prototype in order to find out more active xanthine derivatives.

7-Substituted pyrrolo[2,3-d]pyrimidines for the synthesis of new 1-deazapyrimido[1,2,3-cd]purines

Few examples of new heterocyclic 1-deazapyrimido[1,2,3-cd]purine derivatives were synthesized by intramolecular cyclization of methyl 7-(oxiran-2-ylmethyl)-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylates. The latter were obtained by iodolactonization of 7-allylpyrrolo[2,3-d]pyrimidine-6-carboxylic acids.

Similarities and differences in affinity and binding modes of tricyclic pyrimido- and pyrazinoxanthines at human and rat adenosine receptors

A new series of 32 pyrimido- and 5 tetrahydropyrazino[2,1-f]purinediones was obtained and evaluated for their adenosine receptors (ARs) affinities. The 1,3-dibutyl derivative of 9-(4-(2-(dimethylamino)ethoxy)phenyl)-6,7,8,9-tetrahydropyrimido[1,2-f]purine-2,4(1H,3H)-dione was found to be the most potent A1 AR antagonist of the present series, showing selectivity over the other AR subtypes. The structure-activity for the obtained purinediones was established. Docking experiments of the investigated library to homology models of the human and rat A1 and A2A ARs allowed to compare the expected binding modes for selected compounds. The detailed analysis of binding cavities within individual AR subtypes indicated small but significant structural variations that may underlie the observed differences in binding affinities of purinediones at particular subtypes and species.