Development of Kinase Inhibitors via Metal-Catalyzed C⁻H Arylation of 8-Alkyl-thiazolo[5,4-f]-quinazolin-9-ones Designed by Fragment-Growing Studies.

Efficient metal catalyzed C⁻H arylation of 8-alkyl-thiazolo[5,4-f]-quinazolin-9-ones was explored for SAR studies. Application of this powerful chemical tool at the last stage of the synthesis of kinase inhibitors allowed the synthesis of arrays of molecules inspired by fragment-growing studies generated by molecular modeling calculations. Among the potentially active compounds designed through this strategy, FC162 (4c) exhibits nanomolar IC50 values against some kinases, and is the best candidate for the development as a DYRK kinase inhibitor.

Synthesis of Bioactive 2-(Arylamino)thiazolo[5,4-f]-quinazolin-9-ones via the Hügershoff Reaction or Cu- Catalyzed Intramolecular C-S Bond Formation.

A library of thirty eight novel thiazolo[5,4-f]quinazolin-9(8H)-one derivatives (series 8, 10, 14 and 17) was prepared via the Hügershoff reaction and a Cu catalyzed intramolecular C-S bond formation, helped by microwave-assisted technology when required. The efficient multistep synthesis of the key 6-amino-3-cyclopropylquinazolin-4(3H)-one (3) has been reinvestigated and performed on a multigram scale from the starting 5-nitroanthranilic acid. The inhibitory potency of the final products was evaluated against five kinases involved in Alzheimer's disease and showed that some molecules of the 17 series described in this paper are particularly promising for the development of novel multi-target inhibitors of kinases.

Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part I.

The convenient synthesis of a library of novel 6,6,5-tricyclic thiazolo[5,4-f] quinazolines (forty molecules) was achieved mainly under microwave irradiation. Dimroth rearrangement and 4,5-dichloro-1,2,3,-dithiazolium chloride (Appel salt) chemistry were associated for the synthesis of a novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (16) a versatile molecular platform for the synthesis of various bioactive derivatives. Kinase inhibition of the final compounds was evaluated on a panel of four Ser/Thr kinases (DYRK1A, CDK5, CK1 and GSK3) chosen for their strong implications in various regulation processes, especially Alzheimer's disease (AD). In view of the results of this preliminary screening, thiazolo[5,4-f]quinazoline scaffolds constitutes a promising source of inspiration for the synthesis of novel bioactive molecules. Among the compounds of this novel chemolibrary, 7i, 8i and 9i inhibited DYRK1A with IC50 values ranging in the double-digit nanomolar range (40, 47 and 50 nM, respectively).

Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part II.

The convenient synthesis of a focused library (forty molecules) of novel 6,6,5-tricyclic thiazolo[5,4-f]quinazolines was realized mainly under microwave irradiation. A novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (1) was used as a versatile molecular platform for the synthesis of various derivatives. Kinase inhibition, of the obtained final compounds, was evaluated on a panel of two kinases (DYRK1A/1B) together with some known reference DYRK1A and DYRK1B inhibitors (harmine, TG003, NCGC-00189310 and leucettine L41). Compound IC50 values were obtained and compared. Five of the novel thiazolo[5,4-f]quinazoline derivatives prepared, EHT 5372 (8c), EHT 6840 (8h), EHT 1610 (8i), EHT 9851 (8k) and EHT 3356 (9b) displayed single-digit nanomolar or subnanomolar IC50 values and are among the most potent DYRK1A/1B inhibitors disclosed to date. DYRK1A/1B kinases are known to be involved in the regulation of various molecular pathways associated with oncology, neurodegenerative diseases (such as Alzheimer disease, AD, or other tauopathies), genetic diseases (such as Down Syndrome, DS), as well as diseases involved in abnormal pre-mRNA splicing. The compounds described in this communication constitute a highly potent set of novel molecular probes to evaluate the biology/pharmacology of DYR1A/1B in such diseases.

Exploring Kinase Inhibition Properties of 9H-pyrimido[5,4-b]- and [4,5-b]indol-4-amine Derivatives.

We previously highlighted the interest in 6,5,6-fused tricyclic analogues of 4-aminoquinazolines as kinase inhibitors in the micromolar to the nanomolar range of IC50 values. For the generation of chemical libraries, the formamide-mediated cyclization of the cyanoamidine precursors was carried out under microwave irradiation in an eco-friendly approach. In order to explore more in-depth the pharmacological interest in such tricyclic skeletons, the central five member ring, i.e., thiophène or furan, was replaced by a pyrrole to afford 9H-pyrimido[5,4-b]- and [4,5-b]indol-4-amine derivatives inspired from harmine. The inhibitory potency of the final products was determined against four protein kinases (CDK5/p25, CK1/ε, GSK3 and DYRK1A). As a result, we have identified promising compounds targeting CK1/ε and DYRK1A and displaying micromolar and submicromolar IC50 values.

Synthesis and biological evaluation of N-aryl-7-methoxybenzo[b]furo[3,2-d]pyrimidin-4-amines and their N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amine analogues as dual inhibitors of CLK1 and DYRK1A kinases.

Novel N-aryl-7-methoxybenzo[b]furo[3,2-d]pyrimidin-4-amines (1) and their N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amine analogues (2) were designed and prepared for the first time via microwave-accelerated multi-step synthesis. Various anilines were condensed with N'-(2-cyanaryl)-N,N-dimethylformimidamide intermediates obtained by reaction of 3-amino-6-methoxybenzofuran-2-carbonitrile (3) and 3-amino-6-methoxybenzothiophene-2-carbonitrile (4) precursors with dimethylformamide dimethylacetal. The inhibitory potency of the final products against five protein kinases (CDK5/p25, CK1δ/ε, GSK3α/ß, DYRK1A and CLK1) was estimated. Compounds (2a-z) turned out to be particularly promising for the development of new pharmacological dual inhibitors of CLK1 and DYRK1A kinases.

Synthesis and biological evaluation of N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amines and their pyrido and pyrazino analogues as Ser/Thr kinase inhibitors.

A useful and rapid access to libraries of N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amines and their pyrido and pyrazino analogues was designed and optimized for the first time via microwave-accelerated condensation and Dimroth rearrangement of the starting anilines with N'-(2-cyanoaryl)-N,N-dimethylformimidamides obtained by reaction of thiophene precursors with dimethylformamide dimethylacetal. The inhibitory potency of the final products against five protein kinases (CDK5/p25, CK1δ/ɛ, GSK3α/ß, DYRK1A and CLK1) was estimated. N-arylpyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4-amine series of compounds (4a-j) turned out to be particularly promising for the development of new pharmacological inhibitors of CK1 and CLK1 kinases.