An Unusual Michael Addition of 3,3-Dimethoxypropanenitrile to 2-Aryl Acrylates: A Convenient Route to 4-Unsubstituted 5,6-Dihydropyrido[2,3-d]pyrimidines

The Use of a Penta-Deuterophenyl Substituent to Improve the Metabolic Stability of a Tyrosine Kinase Inhibitor

In cases in which a rapid metabolism is the cause of an unfavorable pharmacokinetic profile, it is important to determine the Sites of Metabolism (SoMs) of a molecule to introduce the necessary modifications to improve the stability of the compound. The substitution of hydrogen atoms by deuterium atoms has been proposed to ameliorate such properties due to the greater stability of the C-D bonds. IQS016, bearing a 2-phenylamino substituent, is a compound previously described by our group with good biological activity as a discoidin domain receptor (DDR2) inhibitor but suffers from low metabolic stability determined in a test with rat-liver microsomes (less than 50% of the initial compound after 60 min). We have obtained the corresponding 2-(penta-deuterophenyl) analog (IQS016-d5) from aniline-2,3,4,5,6-d5 showing that it has a better metabolic stability than IQS016 and a higher inhibitory effect on isolated tyrosine kinase receptors but not a better 2D in vitro effect.

Synthetic Scope of Brønsted Acid-Catalyzed Reactions of Carbonyl Compounds and Ethyl Diazoacetate

The comprehensive study of the reactions of carbonyl compounds and ethyl diazoacetate in the presence of a Brønsted acid catalyst is described. In result, a broad range of 3-oxo-esters were synthesized from a variety of ketones and aliphatic aldehydes by 1,2-aryl/alkyl/hydride shift. Aryl-methyl ketones produced only aryl-migrated products, whereas other ketones yielded a mixture of products. For diaryl ketones, the identity of two inseparable migrated products was confirmed by two-dimensional NMR spectroscopy.

Pyrido[2,3-d]pyrimidin-7(8H)-ones: Synthesis and Biomedical Applications

Pyrido[2,3-d]pyrimidines (1) are a type of privileged heterocyclic scaffolds capable of providing ligands for several receptors in the body. Among such structures, our group and others have been particularly interested in pyrido[2,3-d]pyrimidine-7(8H)-ones (2) due to the similitude with nitrogen bases present in DNA and RNA. Currently there are more than 20,000 structures 2 described which correspond to around 2900 references (half of them being patents). Furthermore, the number of references containing compounds of general structure 2 have increased almost exponentially in the last 10 years. The present review covers the synthetic methods used for the synthesis of pyrido[2,3-d]pyrimidine-7(8H)-ones (2), both starting from a preformed pyrimidine ring or a pyridine ring, and the biomedical applications of such compounds.

Design, synthesis and biological evaluation of pyrido[2,3-d]pyrimidin-7-(8H)-ones as HCV inhibitors

The design and selection of a combinatorial library of pyrido[2,3-d]pyrimidin-7(8H)-ones (4) has allowed the synthesis of 121 compounds, using known and new synthetic methodologies, and the evaluation of the inhibitory activity against hepatitis C virus (HCV) genotype 1b replicon. Among these compounds, 21{4,10} and 24{2,10} presented very high activities [EC50 = 0.027 μM (CC50 = 5.3 μM) and EC50 = 0.034 μM (CC50 = 13.5 μM), respectively] and high selectivity indexes, 196 and 397. These values are similar to the EC50 reported for sofosbuvir (2) (0.048 μM) using a similar methodological approach and the same virus subtype. 21{4,10} and 24{2,10} are obtained through shorter synthetic itineraries than sofosbuvir and 24{2,10} is achiral contrary to sofosbuvir which presents 4 stereogenic centers. In silico studies suggest that 21{4,10} and 24{2,10} inhibits NS5B polymerase through allosteric site binding.

A facile approach to the synthesis of structurally diverse 6,8a-dihydropyrido[2,3-d]pyrimidine derivatives via a three-component domino reaction

A concise and efficient approach to the synthesis of structurally diverse 6,8a-dihydropyrido[2,3-d]pyrimidine derivatives has been accomplished for the first-time by a three-component reaction involving alkylsulfonyl acetonitrile, an aromatic aldehyde, and 6-aminouracil.

Synthesis and isolation of methacrylate- and acrylate-functionalized polyhedral oligomeric silsesquioxanes (T8, T10, and T12) and characterization of the relationship between their chemical structures and physical properties

Novel organic-inorganic hybrid nanobuilding blocks of methacrylate- and acrylate-functionalized polyhedral oligomeric silsesquioxanes were easily prepared via nucleophilic substitution on octakis(3-chloropropyl)octasilsesquioxane, using sodium methacrylate and sodium acrylate, respectively. From a practical standpoint, these cage-rearranged silsesquioxanes (T8, T10, and T12) could be readily isolated in their pure form with conventional silica gel column chromatography. Octakis(3-propyl methacrylate)octasilsesquioxane (T8) is a colorless, crystalline solid with a melting point of 66.7-67.2 °C, while other cage products are colorless viscous liquids at room temperature. Moreover, we report that the chemical structure/physical property relationship of silsesquioxane cages not only is dependent on the symmetry of the inorganic silsesquioxane core at a given temperature but also is dictated by the organic substituent mobility. Structures of the products were confirmed by (1)H, (13)C, and (29)Si NMR spectroscopy and high resolution electrospray ionization mass spectrometry analysis.

Synthesis of 2-arylamino substituted 5,6-dihydropyrido[2,3-d]pyrimidine-7(8H)-ones from arylguanidines

A practical protocol was developed for the synthesis of 2-arylamino substituted 4-amino-5,6-dihydropyrido[2,3-d]pyrimidin-7(8H)-ones from α,β-unsaturated esters, malononitrile, and an aryl substituted guanidine via the corresponding 3-aryl-3,4,5,6- tetrahydropyrido[2,3-d]pyrimidin-7(8H)-ones. Such compounds are formed upon treatment of 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles with an aryl substituted guanidine in 1,4-dioxane and are converted to the desired 4-aminopyridopyrimidines with NaOMe/MeOH through a Dimroth rearrangement. The overall yields of this three-step protocol are, generally speaking, higher than the multicomponent reaction, previously developed by our group, between an α,β-unsaturated ester, malononitrile, and an aryl substituted guanidine.

A diversity-oriented synthesis of 3-(2-amino-1,6-dihydro-6-oxo-pyrimidin-5-yl)propanoic esters

The synthesis of dimethyl 2-(methoxymethylene) pentanedioates by an unusual Michael addition of 3,3-dimethoxypropionate to α, β-unsaturated esters is described. These new intermediates can subsequently be converted to methyl 3-(2-amino-1,6-dihydro-6-oxo-pyrimidin-5-yl)propanoates upon treatment with guanidine carbonate. The resulting pyrimidine derivatives are open-chain analogues of pyrido[2,3-d]pyrimidines with interesting biological activities.