A novel and chemoselective process of N-alkylation of aromatic nitrogen compounds using quaternary ammonium salts as starting material

Artículo Internacional Open AccesThe process of N-alkylation of several pyrroles, indoles, and derivative heterocycles is herein described, using quaternary ammonium salts as the source of an alkylating agent. These reactions were carried out on several heterocyclic rings with triethylbenzylammonium chloride or tetradecyltrimethyl ammonium bromide and an NaOH solution at 50%, leading to a chemoselective N-alkylated product and an average yield of 73%. This is an alternative process to the traditional benzylation and methylation of N-heterocycles with direct handling of alkyl halides.CONACYT, Secretaría de Investigación y Estudios Avanzados de la UAE

Synthesis and antifungal activity of novel oxazolidin-2-one linked-1,2,3-triazole derivatives

Artículo IndizadoNovel oxazolidin-2-one-linked 1,2,3-triazole derivatives (4a–k) were synthesized by straightforward and versatile azide–enolate (3 + 2) cycloaddition. The series of compounds was screened for antifungal activity against four filamentous fungi as well as six yeast species of Candida spp. According to their efficiency and breadth of scope, they can be ordered as 4k > 4d > 4h > 4a, especially in relation to the activity displayed against Candida glabrata ATCC-34138, Trichosporon cutaneum ATCC-28592 and Mucor hiemalis ATCC-8690, i.e. compounds 4d, 4h and 4k showed excellent activity against C. glabrata (MIC 0.12, 0.25 and 0.12 μg mL−1, respectively), better than that of itraconazole (MIC 1 μg ml−1). The activity of compound 4d (MIC = 2 μg mL− 1) was higher than that observed for the standard antifungal drug (MIC = 8 μg mL−1) against Trichosporon cutaneum, while compound 4k displayed an excellent antimycotic activity against Mucor hiemalis (MIC = 2 μg mL−1 vs. 4 μg mL−1 for itraconazole). In addition, we describe herein a novel mild and eco-friendly synthetic protocol for obtaining β-ketosulfones (adducts to afford compounds 4a–k) from α-brominated carbonyls in an aqueous nanomicellar medium at room temperature.CONACYT, Secretaría de Investigación de Estudios Avanzados de la UAE

Highly Regio- and Stereoselective Diels-Alder Cycloadditions via Two-Step and Multicomponent Reactions Promoted by Infrared Irradiation under Solvent-Free Conditions

Infrared irradiation promoted the Diels-Alder cycloadditions of exo-2-oxazolidinone dienes 1–3 with the Knoevenagel adducts 4–6, as dienophiles, leading to the synthesis of new 3,5-diphenyltetrahydrobenzo[d]oxazol-2-one derivatives (7, 9, 11 and 13–17), under solvent-free conditions. These cycloadditions were performed with good regio- and stereoselectivity, favoring the para-endo cycloadducts. We also evaluated the one-pot three-component reaction of active methylene compounds 20, benzaldehydes 21 and exo-2-oxazolidinone diene 2 under the same reaction conditions. A cascade Knoevenagel condensation/Diels-Alder cycloaddition reaction was observed, resulting in the final adducts 13–16 in similar yields. These procedures are environmentally benign, because no solvent and no catalyst were employed in these processes. The regioselectivity of these reactions was rationalized by Frontier Molecular Orbital (FMO) calculations

Circulating tumor and immune cells for minimally invasive risk stratification of smoldering multiple myeloma

Early intervention in smoldering multiple myeloma (SMM) requires optimal risk stratification to avoid under and over-treatment. We hypothesized that replacing bone marrow (BM) plasma cells (PCs) for circulating tumor cells (CTCs), and adding immune biomarkers in peripheral blood (PB) for the identification of patients at risk of progression due to lost immune surveillance, could improve the International Myeloma Working Group 20/2/20 model