Alkaline earth metal catalyzed cascade, one-pot, solvent-free, and scalable synthesis of pyranocoumarins and benzo[b]pyrans

Facile and Chemically Sustainable Catalyst‐Free Synthesis of Diverse 2‐Aryl‐4‐Alkyl/Aryl‐Pyrano[3,2‐c]chromen‐5(4H)‐Ones by One‐Pot Multicomponent Reactions at Room Temperature

“…All the isolated products were fully characterized on the basis of their analytical data and detailed spectral studies including FT‐IR, 1 H NMR, 13 C NMR and TOF‐MS. A majority of the entries are synthesized new and the only six known compounds ( 4 a ‐ c , 4 e , 4 h , 4 v ) had physical and spectroscopic data identical to the literature values ,,…”

“…Then we performed the same reaction for several times using ethanol, water, and ethanol‐water mixtures in varying proportions ( v / v ) as solvents at ambient conditions (25‐30 °C), and observed that the reaction underwent smoothly in aqueous ethanol (1:1 v / v ) affording the desired product 4 a in 86 % yield at 12 h (Table , entry 4). Compound 4 a was characterized by its physical and spectral properties . The overall results are summarized in Table .…”

“…Pyrano[3,2‐ c ]coumarins or pyrano[3,2‐ c ]chromen ‐ 5(4 H )‐ones are usually synthesized from the tandem reaction of commercially available 4‐hydroxycoumarins with varying suitable electrophiles such as 1,3‐diarylallylic compounds, propargylic alcohols and α,β‐unsaturated carbonyl compounds. All these earlier methods have certain merits of their own, but also suffer from various constraints such as heating and hazardous reactions conditions, use of strong acid conditions like I 2 ‐H 2 SO 4 and I 2 ‐AcOH, expensive transition metal catalysts like Ru, AuCl 3 –AgOTf in toluene and Bi(OTf) 3 , Ca(OTf) 2 /Bu 4 NPF 6 , stoichiometric loading of DDQ, toxic reagents,– and also use of less available catalysts, substrates, microwave irradiation, and with poor yields and regioselectivity . Hence, a search for simple and efficient, mild and clean, cost‐effective, high‐yielding, and environmentally benign routes to this class of biologically relevant O ‐heterocycles remains a valid exercise.…”

Preparation, characterization and catalytic application of nano-Fe3O4@SiO2@(CH2)3OCO2Na as a novel basic magnetic nanocatalyst for the synthesis of new pyranocoumarin derivatives

“…[13][14][15][16] In view of the biological, industrial, and synthetic importance of pyranocoumarins, several methods for their synthesis have been reported. [17][18][19] Although most of these processes have distinct advantages, the use of high temperatures, environmentally harmful catalysts, harsh reaction conditions, long reaction times and large quantity of volatile organic solvents limit the use of these methods. Therefore, the search for the possibility synthesis of these compounds under mild reaction conditions with recoverable effective heterogeneous catalyst is still in high demand.…”

Magnetically Recyclable Nano-FDP: A Novel, Efficient Nano-Organocatalyst for the One-Pot Multi-Component Synthesis of Pyran Derivatives in Water Under Ultrasound Irradiation

“…1) like anti-tumour, anti-cancer, anti-microbial, anti-oxidant, anti-proliferative, anti-inflammatory, anti-HIV, anti-tumour, analgesics etc. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. On continuing our exploration for synthesis and application of different nanoparticles in multi-component reactions [31], we herein report a novel method for synthesis of nano-Fe 3 O 4 -DOPA-L-proline (nano-FDP) which shows extraordinary catalytic activity in one-pot, multi-component synthesis of pyran derivatives under ultrasonic irradiation.…”