Daniel Blanco-Ania

Synthesis of Hydantoins and Thiohydantoins Spiro-Fused to Pyrrolidines: Druglike Molecules Based on the 2-Arylethyl Amine Scaffold

The synthesis of a 144-compound library of hydantoins and thiohydantoins spiro-fused to pyrrolidines is described. These compounds are synthesized from beta-aryl pyrrolidines, providing products with the 2-arylethyl amine moiety, a structural feature often encountered in compounds active in the central nervous system. All possible stereoisomers of the two-stereocenter products are synthesized. The 80-membered hydantoin sublibrary was obtained with yields ranging from 58 to 100% (87% average) and purities from 51 to 100% (87% average) and the 64-membered thiohydantoin sublibrary was obtained with yields ranging from 65 to 100% (89% average) and purities from 67 to 100% (93% average).

Synthesis of dihydrouracils spiro-fused to pyrrolidines: druglike molecules based on the 2-arylethyl amine scaffold.

The synthesis of a small library of dihydrouracils spiro-fused to pyrrolidines is described. These compounds are synthesized from β-aryl pyrrolidines, providing products with the 2-arylethyl amine moiety, a structural feature often encountered in compounds active in the central nervous system. The β-aryl pyrrolidines are synthesized through a three-step methodology that includes a Knoevenagel condensation reaction, a 1,3-dipolar cycloaddition reaction, and a nitrile reduction.

Pd-Catalyzed Hydroamination of Alkoxyallenes with Azole Heterocycles: Examples and Mechanistic Proposal

Palladium-catalyzed regio- and enantioselective addition of azole heterocycles to alkoxyallenes was developed (up to 92% yields and up to 94% ee). DFT calculations suggest a new Pd(0)-driven mechanistic pathway proceeding through protonation of the Pd-coordinated allene (4-PdL2), which develops a strongly nucleophilic character at the central C atom.

Solution-Phase Parallel Annulation of (Thio)hydantoins to Tetrahydroisoquinolines and Tetrahydro-beta-carbolines Containing the 2-Arylethyl Amine Scaffold

The one-step solution-phase parallel synthesis of two structurally diverse libraries of pharmacologically important compounds is described. The presented compounds combine three privileged structures: the 2-arylethyl amine moiety, a tetrahydro(hetero)areno[c]pyridine, and a (thio)hydantoin. These compounds are synthesized by annulation of a hydantoin or a 2-thiohydantoin ring to tri- or tetracyclic scaffolds, containing the 2-arylethyl amine moiety and a tetrahydroisoquinoline, a tetrahydro-beta-carboline, or a tetrahydrofuro[3,2-c]pyridine. The annulation leads to pharmacologically relevant structural motifs such as imidazopyrroloisoquinolines, dioxoloimidazopyrroloisoquinolines, furoimidazopyrrolopyridines, and imidazopyrrolopyridoindoles. Both libraries were obtained with quantitative yields. The 36-membered hydantoin library was obtained with purities from 57 to 100% (90% average) and the 32-membered thiohydantoin library with purities from 73 to 100% (94% average).

Strigolactones: new plant hormones in the spotlight

The development and growth of plants are regulated by interplay of a plethora of complex chemical reactions in which plant hormones play a pivotal role. In recent years, a group of new plant hormones, namely strigolactones (SLs), was discovered and identified. The first SL, strigol, was isolated in 1966, but it took almost 20 years before the details of its structure were fully elucidated. At present, two families of SLs are known, one having the stereochemistry of (+)-strigol and the other that of (-)-orobanchol, the most abundant naturally occurring SL. The most well-known bioproperty of SLs is the germination of seeds of the parasitic weeds Striga and Orobanche. It is evident that SLs are going to play a prominent role in modern molecular botany. In this review, relevant molecular and bioproperties of SLs are discussed. Items of importance are the effect of stereochemistry, structure-activity relationships, design and synthesis of analogues with a simple structure, but with retention of bioactivity, introduction of fluorescent labels into SLs, biosynthetic origin of SLs, mode of action in plants, application in agriculture for the control of parasitic weeds, stimulation of the branching of arbuscular mycorrhizal (AM) fungi, and the control of plant architecture. The future potential of SLs in molecular botany is highlighted.

Trifluoromethyl Vinyl Sulfide: A Building Block for the Synthesis of CF3S-Containing Isoxazolidines

Trifluoromethyl vinyl sulfide, a potential building block for pharmaceutically and agrochemically relevant products, is prepared and used for the first time in high-pressure-mediated 1,3-dipolar cycloaddition reactions with nitrones to synthesize (trifluoromethyl)sulfanyl isoxazolidines.

Cu-catalysed pyrazole synthesis in continuous flow

The synthesis of 1,4-disubstituted pyrazoles via the cycloaddition reaction of sydnones and terminal alkynes has been achieved employing silica-supported copper catalysts. Furthermore, this methodology has been successfully implemented in continuous flow conditions using prepacked stainless steel cartridges containing the solid-supported copper promoter. Finally, we demonstrate that this synthetic procedure can be successfully scaled up to produce practically useful amounts of pyrazole products within 2–5 hours.

A facile route to hydrophilic ionic liquids

Ionic liquids, organic room-temperature molten salts have percolated into many fields of science. A major problem for many applications, however, is caused by the commonly fluorinated anion, that on contact with water decomposes to release HF. Ionic liquids with hydrophilic anions do not have these problems. In addition, because of their tuneable hydrophilicity, they interface better with biotechnology, providing a route to truly ‘tuneable water.’ Currently available synthetic routes, however, contain strong disadvantages which may have caused the underexposure of this class of ionic liquids. In this manuscript, we provide a novel facile route to ionic liquid crystals with different hydrophilic anions, yielding pure materials as a result of our very mild reaction conditions. Our generic approach may be used to prepare conventional ionic liquids, but also provides access to functionalised ionic liquids.

Synthesis of 3-Amino-1-benzothiophene-1,1-diones by Alkyne Directed Hydroarylation and 1/N→3/C-Sulfonyl Migration: Synthesis of 3-Amino-1-benzothiophene-1,1-diones by Alkyne Directed Hydroarylation and 1/N→3/C-Sulfonyl Migration

A completely regioselective and highly stereoselective palladium‐catalyzed intramolecular hydroarylation of arenesulfonyl ynamines to benzothiazoles was developed. The presence of an electron‐withdrawing group on the triple bond of the sulfonyl ynamine was crucial for the success of the reaction and our mechanistic studies suggest an alkyne‐directed 5‐exo‐dig cyclization pathway. The products easily underwent photoinduced rearrangement to 3‐amino‐1‐benzothiophene‐1,1‐diones (up to 35 % yields after two steps).

Carbonylonium ions: the onium ions of the carbonyl group

The nomenclature of cations R1C(=O+R3)R2 (R1, R2, R3 = H or organyl) has been examined and shown to be in a state of immeasurable confusion: a pragmatic recommendation is made that the generic term “carbonylonium ions” should be adopted for these intermediates, which comprises the terms “aldehydium” (R1 = H, R2, R3 = H or organyl) and “ketonium ions” (R1, R2 = organyl, R3 = H or organyl) for the corresponding aldehyde- and ketone-based intermediates, respectively.