Diammonium Hydrogen Phosphate: An Efficient and Versatile Catalyst for the One‐Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives in Aqueous Media

An Efficient Synthesis of Pyrido[2,3-<i>d</i>]pyrimidine Derivatives via One-Pot Three-Component Reaction in Aqueous Media

“…With the aim to develop more efficient processes, reduce the number of separate reaction steps, and minimize byproducts for the synthesis of pyrido [2,3-d]pyrimidines [39,40], and in continuation of our previous work on the development of new and efficient methods for the preparation of heterocyclic compounds [41][42][43][44][45], a convenient, practical, inexpensive, rapid procedure for the preparation of pyrido [2,3-d]pyrimidine derivatives 4(a-h) was reported (Scheme 1, methods A, B).…”

Potassium Phosphate Catalyzed a Rapid Three-Component Synthesis of Tetrahydrobenzo[b]pyran at Ambient Temperature

“…In addition, the tetrahydrobenzo[b]pyran nucleus is an important structural motif of a series of natural products [8,9] and can be converted into pyridine systems which relate to pharmacologically important calcium antagonists of the dihydropyridine(DHP) [10,11] type. The importance of these compounds has led the scientific community to synthesize them using the bicomponent condensation [12,13] of dimedone with a-cyanocinnamonitriles or multicomponent condensation [14][15][16][17][18][19] of dimedone with aromatic aldehydes and malononitrile.…”

N,N‐dimethylamino‐functionalized basic ionic liquid catalyzed one‐pot multicomponent reaction for the synthesis of 4H‐benzo[b]pyran derivatives under solvent‐free condition

“…The use of microwave [6] and ultrasound irradiations [7] is also reported for the synthesis of pyrans. Recently, many methods have been reported for the preparation of 4H-benzo-[b]pyrans through two-component [8] or three-component condensation including the use of 4-dodecylbenzenesulfonic acid [9], rare earth perfluorooctanoate (RE(PFO) 3 ) [10], (NH 4 ) 2 HPO 4 [11], NaBr [12], tetramethyl ammonium hydroxide [13], basic ionic liquid ([bmim] + OH − ) [14], …”