Synthesis of 5H-benzimidazo[1,2-a][1,3,4]thiadiazolo[2,3-d][1,3,5]triazin-5-one and 12H-benzimidazo[1,2-a]pyrimido[6,1-d][1,3,5]triazin-12-one,two new heterocyclic ring systems

2-(2,6-Dimethylpyrimidin-4-ylaminobenzimidazole) (VIIa) and 2-(1,3,4-thiadiazol-2-ylamino)benzimidazole (VIIb) underwent a ring-closure reaction with phosgene giving 1,3-dimethyl-12H-benzirnidazo[1,2-a]pyrirnido[6,1][-d][1,3,5]triazin-12-one (IIa) and 5H-benzimidazo[1,2-a][1,3,4]thiadiazolo[2,3-d][1,3,5]triazin-5-one (IIb) two hitherto unknown heterocyclic systems. A convenient synthesis of 2,6-dimethyl-4-aminopyrimidine is described.     

Synthesis of 2-oxazolines mediated by N,N′-diisopropylcarbodiimide

N-(β-Hydroxy)amides can be cyclised by reaction with diisopropylcarbodiimide (DIC) to give the corresponding 2-oxazolines in high yields. The reaction requires only very mild Lewis-acid catalysis (5 mol % Cu(OTf)₂) and can be accomplished with simple heating, or in very short reaction times under microwave irradiation.     

Gadolinium‐Decorated Silica Microspheres as Redox‐Responsive MRI Probes for Applications in Cell Therapy Follow‐Up

The redox microenvironment within a cell graft can be considered as an indicator to assess whether the graft is metabolically active or hypoxic. We present a redox‐responsive MRI probe based on porous silica microparticles whose surface has been decorated with a Gd‐chelate through a disulphide bridge. Such microparticles are designed to be interspersed with therapeutic cells within a biocompatible hydrogel. The onset of reducing conditions within the hydrogel is paralleled by an increased clearance of Gd, that can be detected by MRI.     

A simple,efficient, regioselective and one-pot preparation of N-hydroxy- and N–O-protected hydroxyindoles via cycloaddition of nitrosoarenes with alkynes. Synthetic scope,applications and novel by-products

The thermal reaction between nitrosoarenes and alkynes under alkylating conditions produces N-alkoxyindoles as the major products in moderate to good yields and excellent regioselectivity. Various electrophiles are used affording different N–O-protected hydroxyindoles in a multi-component fashion. Privileged acetylenic substrates used in reactions with substituted nitrosoarenes are arylalkynes or propiolates. Potentially bioactive compounds and other classes of highly functionalizable indole products were prepared. Reactions between o-carbomethoxy-nitrosoarenes and arylacetylenes provided tricyclic compounds containing an acylaziridine indoline skeleton.