Four component synthesis of highly functionalized pyrano[2,3-c]pyrazoles from benzyl halides

N-methylmorpholine N-oxide and silver oxide (Ag₂O) oxidized four component reaction for the preparation of pyranopyrazole with different substituted pattern have been developed which provides rapid access to a library of compounds in good to excellent yields by using benzyl halide, malanonitrile/ethyl cyanoacetate, diethylacetylenedicarboxylate/ethyl acetoacetate and hydrazine hydrate as reactants. This transformation involves the breaking of one C?O bond and formation of 2 C–C, 2 C–N, and a C?O bond leading to the formation of a five and six membered ring in one pot operation.     

Synthesis of 4,6-diarylpyrimidin-2(1H)-one derivatives from benzyl halides and (1-bromoethyl)benzene under solvent-free conditions

A facile synthesis of a series of pyrimidinone derivatives from the reaction of benzyl halides, (1-bromoethyl)benzene and urea in the presence of pyridine N-oxide (PNO) under solvent-free conditions is described. This transformation presumeably occurs via oxidation/cross-aldol condensation/Michael addition/intra molecular cyclization, domino sequence, involving the formation of one C–C bond and two C–N bonds in a single step.     

Determination of 77 Multiclass Pesticides and Their Metabolitesin Capsicum and Tomato Using GC-MS/MS and LC-MS/MS

A quick, sensitive, and reproducible analytical method for the determination of 77 multiclass pesticides and their metabolites in Capsicum and tomato by gas and liquid chromatography tandem mass spectrometry was standardized and validated. The limit of detection of 0.19 to 10.91 and limit of quantification of 0.63 to 36.34 µg·kg⁻¹ for Capsicum and 0.10 to 9.55 µg·kg⁻¹ (LOD) and 0.35 to 33.43 µg·kg⁻¹ (LOQ) for tomato. The method involves extraction of sample with acetonitrile, purification by dispersive solid phase extraction using primary secondary amine and graphitized carbon black. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 20%. Similarly, the method precision was evaluated interms of repeatability (RSDr) and reproducibility (RSD_wR) by spiking of mixed pesticides standards at 100 µg·kg⁻¹ recorded anRSD of less than 20%. The matrix effect was acceptable and no significant variation was observed in both the matrices except for few pesticides. The estimated measurement uncertainty found acceptable for all the pesticides. This method found suitable for analysis of vegetable samples drawn from market and farm gates.     

Multicomponent reaction of benzyl halides: Synthesis of [1,2,4]triazolo/benzimidazolo quinazolinones

We demonstrated a simple, highly efficient, one-pot method to construct triazolo/benzimidazolo quinazolinones through a cascade of oxidation, Knoevenagel condensation, and Michael addition followed by cyclization and dehydration. This protocol tolerates easily available benzyl halides, 2-amino benzimidazole/3-amino-1,2,4-triazole, and α-hydroxy C-H acids as starting materials using trimethyl amine N-oxide in ethanol. To the best of our knowledge, this is the first example of synthesis of triazolo/benzimidazolo quinazolinones directly from benzyl halides in one pot. Simple procedure, environmental friendliness, mild reaction conditions, and good yields are the attractive features of this method.