Chemistry of 3-carbonyl-2-methyl-4-oxo-4H-1-benzopyrans

Abstract

The review article gives a comprehensive survey of the synthesis and chemistry of the title benzopyrans covering the literature published

Chemistry of 2-amino-4-oxo-4H-1-benzopyran-3-carboxaldehydes

“…30 Heterocyclization of the -NH-C(=X)NHNH 2 functionality of 69e with some 1,2-bifunctional electrophiles as ClCOCOCl, ClCH 2 COCl, PhCOCH 2 Br, BrCH(CN) 2 and MeCOCO 2 Na leading to the appropriate 1,2,4-triazole derivatives has also been reported. A mixture of the aldehyde 1 and hydrazine hydrate on being heated with triethylammonium bisulfate (20 mol%) at 120 °C under solvent free conditions affords the bis-hydrazone 75.…”

“…Electrophilicity at their amino substituted C-2 is somewhat reduced due to the positive resonance effect of the amino group and compares well to that at C-2 of 3-formyl-2-methylchromone 8. 2 Again, the chromones 1-4 through their amino groups can function as nucleophiles as 8 does through its 2-methyl group in the presence of an appropriate base. The amino-aldehyde 1 in this respect can be regarded as an aza-analogue of the aldehyde 8.…”

Chemical Transformation of Chromones into Coumarins

“…Polyfluorochromone-3-carboxylates 66 reacted with a variety of primary amines, under different reaction conditions, producing chromane-2,4(3Н)-diones 72 (Scheme 58). [66][67][68]72,74,75 Scheme 58…”

Continuous flow hydrogenation with Pd complexes of pyridine‐benzotriazole ligands

“…Therefore, in recent years, continuous flow method has been an important tool for the efficiency and reusability of heterogeneous catalysts, [9][10][11][12][13][14][15][16][17] among many other synthetic organic applications. [18][19][20][21][22] Recently, Yu et al published a minreview [23] to evaluate innovations in continuous flow hydrogenation studies. In this study, recent studies on continuous flow homogeneous and heterogeneous catalysis of various organic functional groups such as alkenes and alkynes, [24][25][26][27] imines and nitro, [28,29] and carbonyl [30,31] were examined.…”