Ionic liquid promoted spiroannulation via hetero-Michael addition and intramolecular heterocyclisation

Efficient Catalytic Synthesis of 3,4‐Dihydropyrimidin‐2‐ones/thiones via Little Acidic Ionic Liquid Combined with Rapid Heating Ways

“…In recent years, a number of methods have been developed to effectively accomplish the synthesis of these compounds, such as using various Brønsted acids , Lewis acids , basic catalysts , polymer‐supported reagents , and nan catalysts . However, many of these reported protocols suffer from various drawbacks such as the use of expensive and highly corrosive catalysts, tedious separation procedures, and prolonged reaction times.…”

Green Synthetic Approaches for Medium Ring-Sized Heterocycles of Biological Interest

“…A recent study aiming at developing a common approach to 1,5-benzoxazepines and 1,5-benzoazepines from the condensation of 2,3-diaminophenol with carbonyl compounds through MW-assisted solvent-free conditions has revealed several interesting features [54]. Similar studies with aryl alkyl ketones, e.g., acetophenone (81) in place of acetone proved to be of further interest. It was observed that separation of the products was only feasible when the reaction mixture was quenched immediately after irradiation by addition of a 10% NaHCO 3 solution.…”

“…In contemporaneous studies, Siddiqui and coworkers reported spiroannulation via hetero-Michael addition and intramolecular heterocyclization for the synthesis of novel spiro-5-thiazolidin-2-one-indolo [1,5]benzothiazepine 121 (Scheme 24) from readily available isatin, 4-thioxothiazolidin-2-one, and 2-aminothiophenol using the IL [bmim]OH [81]. The sequence involved initial IL-promoted formation of the Knoevenagel product N-methyl-3-(2-oxo-4-thioxo-2-thiazolidinon-5-ylidene)-1,3-dihydro indol-2-one 120 and subsequent thia-Michael addition and cyclative condensation.…”

Iodine/Water Mediated Parallel Synthesis of Bioactive Diversely Substituted Pyrazolo‐Pyrido‐Pyrimidines and Its Spiro Analogues: An Enviro‐Economic Approach

“…A literature survey revealed that there are only few reports where pyrimidine assimilates with pyrazoles, pyridines and indole moieties , and the available methods suffer from many drawbacks like utilization of highly toxic chemicals, longer reaction time, unsatisfactory yields, drastic reaction conditions, or generation of environmentally hazardous waste. To circumvent these shortcomings and in continuation of our interest on the exploration of environmentally benign synthesis , we have envisioned molecular iodine catalyzed synthesis of diversely substituted pyrazolopyrido‐pyrimidine via multicomponent reaction, commencing with hydrazine, ethyl acetoacetate, 1‐methyl‐6‐amino uracil, and isatin/aldehyde in water (Scheme ). This work materializes as a part of our ongoing research involving molecular iodine as the catalyst and water as the solvent in the synthesis of various heterocyclic molecules .…”