Stannylation reaction and cross-couplings in pyrimidines

In vitro identification of imidazo[1,2-a]pyrazine-based antileishmanial agents and evaluation of L. major casein kinase 1 inhibition

Leishmaniasis constitutes a severe public health problem, with an estimated prevalence of 12 million cases. This potentially fatal disease has a worldwide distribution and in 2012, the fatal Visceral Leishmaniasis (VL) was declared as new emerging disease in Europe, mainly due to global warming, with expected important public health impact. The available treatments are toxic, costly or lead to parasite resistance, thus there is an urgent need for new drugs with new mechanism of action. Previously, we reported the discovery of CTN1122, a potent imidazo[1,2-a]pyrazine-based antileishmanial hit compound targeting L-CK1.2 at low micromolar ranges. Here, we described structurally related, safe and selective compounds endowed with antiparasitic properties, better than miltefosine, the reference therapy by oral route. L-CK1.2 homology model gave the first structural explanations of the role of 4-pyridyl (CTN1122) and 2-aminopyrimidin-4-yl (compound 21) moieties, at the position 3 of the central core, in the low micromolar to nanomolar L-CK1.2 inhibition, whereas N-methylpyrazole derivative 11 remained inactive against the parasite kinase.

Aspects in the Total Syntheses of Higher Terpenoids Starting From Wieland–Miescher Ketone and Its Derivative: A Review

Synthetic studies of higher terpenoids starting from Wieland–Miescher ketone since 2012 have been compiled.

Photoredox Cross-Coupling: Ir/Ni Dual Catalysis for the Synthesis of Benzylic Ethers

Single-electron transmetalation has emerged as an enabling paradigm for the cross-coupling of Csp(3) hybridized organotrifluoroborates. Cross-coupling of α-alkoxymethyltrifluoroborates with aryl and heteroaryl bromides has been demonstrated by employing dual catalysis with a combination of an iridium photoredox catalyst and a Ni cross-coupling catalyst. The resulting method enables the alkoxymethylation of diverse (hetero)arenes under mild, room-temperature conditions.

Viridin analogs derived from steroidal building blocks

Naturally occurring furanosteroids such as viridin and wortmannin have long been known as potent inhibitors of the lipid kinase PI-3K. We have been interested in directly accessing analogs of these complex natural products from abundant steroid feedstock materials. In this communication, we describe the synthesis of viridin/wortmannin hybrid molecules from readily available building blocks that function as PI-3K inhibitors and maintain their electrophilic properties. The compounds also show anti-proliferative effects against a breast cancer line.

Cross-coupling of mesylated phenol derivatives with potassium alkoxymethyltrifluoroborates

Cross-coupling of mesylated phenol derivatives with various potassium alkoxymethyltrifluoroborates has been achieved. The corresponding aryl and heteroaryl alkoxymethyl compounds have been obtained with equal facility with both electron-rich and electron-poor substituents on the activated alcohol.

Pd-catalyzed cross-coupling of functionalized organozinc reagents with thiomethyl-substituted heterocycles

Various thiomethyl-substituted N-heterocycles (pyridines, pyrimidines, pyrazines, pyridazines, triazines, benzothiazoles, benzoxazoles, pyrazoles, benzindazoles, quinazolines, etc.) undergo smooth Pd-catalyzed cross-coupling reactions with functionalized aryl-, heteroaryl-, benzylic-, and alkylzinc reagents using Pd(OAc)(2)/S-Phos as the catalytic system mostly at 25 degrees C. No copper salt is required to perform these reactions.

Organotrifluoroborates and monocoordinated palladium complexes as catalysts--a perfect combination for Suzuki-Miyaura coupling

Monocoordinated palladium catalysts derived from sterically hindered, electron-rich phosphines or N-heterocyclic carbenes have revolutionized the Suzuki-Miyaura coupling reaction. The emergence of organotrifluoroborates has provided important new perspectives for the organoboron component of these reactions. In combination, these two components prove to be extraordinarily powerful partners for cross-coupling reactions.

Preparation of potassium alkoxymethyltrifluoroborates and their cross-coupling with aryl chlorides

A wide variety of alkoxymethyltrifluoroborate substrates were prepared via SN2 displacement of potassium bromomethyltrifluoroborate with various alkoxides in excellent yields. These alkoxymethyltrifluoroborates were effectively cross-coupled with several aryl chlorides. This method provides a unique dissonant disconnect that allows greater flexibility in the design of new and improved synthetic pathways.

Formation of RACK- and grid-type metallosupramolecular architectures and generation of molecular motion by reversible uncoiling of helical ligand strands

The interaction of appropriate metal ions (Pb(II), Zn(II)) with helical ligand strands, obtained by hydrazone polycondensation, generates polymetallic supramolecular architectures of rack and grid types, by uncoiling of the ligand. The interconversion between the helical free ligand and the linearly extended ligand in the complexes produces reversible ion-induced, nanomechanical molecular motions of large amplitude. It has been integrated in an acid-base neutralisation fuelled process, which links the extension/contraction of the ligand strands to alternating changes in pH.

The development of 2-benzimidazole substituted pyrimidine based inhibitors of lymphocyte specific kinase (Lck)

This communication details the synthesis, biological activity, and binding mode of a novel class of 2-benzimidazole substituted pyrimidines. The most potent analogs disclosed showed low nanomolar activity for the inhibition of Lck kinase and a representative analog was co-crystallized with Hck (a structurally related member of the Src family kinases).

Palladium-Catalyzed Arylation and Heteroarylation of Azolopyrimidines

A comparative study of the palladium-catalyzed arylation and heteroarylation of 5-bromoazolopyrimidines shows that aryl and electron-rich heteroaryl boronic acids gave higher yields than those obtained using the corresponding aryl and heteroaryl tributyl stannanes. In contrast, the reaction with electron-poor heteroaryl tributyl stannanes gave better results than the corresponding boronic acids.

Concise Total Syntheses of Variolin B and Deoxyvariolin B

The total synthesis of the marine alkaloid variolin B has been achieved in 8 steps and 17% overall yield, starting from commercially available 4-chloro-2-methylthiopyrimidine. The key reaction involves the tandem deoxygenation and cyclization of a triarylmethanol using a combination of triethylsilane and trifluoroacetic acid. In addition, the deoxygenated analogue was prepared in 6 steps and 23% overall yield, starting from the same starting material.

Novel p38 inhibitors with potent oral efficacy in several models of rheumatoid arthritis

A library of trisubstituted oxazoles, thiazoles, imidazoles (1,2,4- and 2,4,5-substituted) and imidazo[1,2-b]pyridines was prepared and evaluated in vitro as p38alpha inhibitors and in vivo in several models of rheumatoid arthritis. Four structures--32, 37, 45 and 59--were identified as potent inhibitors of p38alpha with high efficacy in the LPS induced TNFalpha release model in the mouse, the adjuvant induced arthritis and the collagen induced arthritis in the rat with ED50s between 1.0 and 9.5 mg/kg p.o.

Reaction of Bromomethylazoles and Tosylmethyl Isocyanide. A Novel Heterocyclization Method for the Synthesis of the Core of Marine Alkaloids Variolins and Related Azolopyrimidines

A novel and efficient synthesis of the pyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidine system, the heterocyclic core of the variolin family of marine alkaloids, is described. The route involves the reaction of 3-bromo-2-(bromomethyl)pyrrolo[2,3-b]pyridine and tosylmethyl isocyanide (TosMIC) under phase-transfer conditions. This unprecedented reaction was also used to synthesize a series of new methoxycarbonyl azolopyrimidines by reaction of TosMIC with bromomethylindoles, bromomethylbenzimidazole, and bromomethylpyrazole. Hydrolysis and decarboxylation of 5-bromo-7-methoxycarbonylpyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidine obtained by this heterocyclization process and installation of the pyrimidine moiety in the C5 position open an alternative approach to complete a total synthesis of variolin B.

Total Syntheses of Variolin B and Deoxyvariolin B1

Two alternative synthetic routes have been developed for the preparation of variolin B and deoxyvariolin B. The strategy is based on the preparation of the core tricyclic ring common to all variolins, pyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidine, followed by a palladium-catalyzed cross-coupling reaction to give the tetracyclic system.

Synthesis of 2-(pyrimidin-4-yl)indoles

The synthesis of 2-substituted isomers of the meridianins, a familiy of bioactive indole alkaloids isolated from the tunicate Aplidium meridianum, was undertaken. The synthetic route comprises six steps, with a microwave promoted Fischer cyclization as the key reaction.

Solid-phase synthesis of endothelin receptor antagonists

A new solid-phase synthesis for ET receptor antagonists suitable for automation is presented. A support bound 2-hydroxybutyric acid derivative was converted to the corresponding ether derivatives using 4-halo-2-methylsulfonylpyrimidines. Subsequent Suzuki coupling with various aryl boronic acids gave the desired antagonists in good yields and purities. Highly potent antagonists with excellent selectivity for ET(A) were obtained.

Synthesis of novel imidazo[1,2-a]pyridines with potent activity against herpesviruses

[reaction: see text] Synthesis of a novel imidazopyridine with potent activity against herpes simplex viruses is presented. Several synthetic approaches that describe the introduction of a C-3 pyrimidine substituent on the imidazopyridine core via construction of the pyrimidine or Stille coupling are outlined. Methodology for efficient installation of C-8 amine substituents was developed. The outlined strategies provide a high-yielding, scalable route that is amenable to rapid analogue synthesis.

Di-[1,10]-phenanthrolinyl diazines: a new family of bis-tridentate chelators

A series of three bis-tridentate bridging ligands has been prepared in which two 1,10-phenanthroline units have been symmetrically appended to a central pyridazine, pyrimidine, or pyrazine ring. These ligands have been treated with [Ru(tpy-d(11))Cl(3)] to afford both mono- and bimetallic complexes that show very self-consistent NMR properties. [structure: see text]

Design and synthesis of potent, selective, and orally bioavailable tetrasubstituted imidazole inhibitors of p38 mitogen-activated protein kinase

Novel potent and selective diarylimidazole inhibitors of p38 MAP (mitogen-activated protein) kinase are described which have activity in both cell-based assays of tumor necrosis factor-alpha (TNF-alpha) release and an animal model of rheumatoid arthritis. The SAR leading to the development of selectivity against c-Raf and JNK2alpha1 kinases is presented, with key features being substitution of the 4-aryl ring with m-trifluoromethyl and substitution of the 5-heteroaryl ring with a 2-amino substituent. Cell-based activity was significantly enhanced by incorporation of a 4-piperidinyl moiety at the 2-position of the imidazole which also enhanced aqueous solubility. In general, oral bioavailability of this class of compounds was found to be poor unless the imidazole was methylated on nitrogen. This work led to identification of 48, a potent (p38 MAP kinase inhibition IC50 0.24 nM) and selective p38 MAP kinase inhibitor which inhibits lipopolysaccharide-stimulated release of TNF-alpha from human blood with an IC50 2.2 nM, shows good oral bioavailability in rat and rhesus monkey, and demonstrates significant improvement in measures of disease progression in a rat adjuvant-induced arthritis model.