Synthesis of Diverse Oxa‐Carbocycle‐Annulated Flavones Using the Combined Claisen Rearrangement and Ring‐Closing Metathesis

A simple and efficient route for the synthesis of oxepine‐, oxocine‐, oxepinone‐, and dioxocine‐angularly annulated flavone skeletons has been developed. The combined Claisen rearrangement and the ring‐closing metathesis are used as key steps for the construction of C₇/C₈–C₆–C₆ tricyclic core structures.     

Design,Synthesis, and Antimicrobial Activity of (E)-4-Phenyl-2H-chromene-3-carbaldehyde O-[(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl]oxime Derivatives

Russian Journal of Organic Chemistry - A new series of 1,4-disubstituted 1,2,3-triazole derivatives tethered to a 2H-chromene scaffold have been synthesized via a click reaction. The synthesized...     

A new strategy for synthesis of 9-benzoyl-4-methylpyrano[2,3-f]chromene-2,8-dione using L-proline as a novel and efficient catalyst

Russian Journal of General Chemistry - We report the high yield synthesis of novel 9-benzoyl-4-methylpyrano[2,3-f]chromene-2,8-dione derivatives obtained by the reaction of...     

Stereoselective total synthesis of paecilomycin E and F and its two congeners Cochliomycin C and 6-epi-Cochliomycin C

An efficient and concise approach to the total synthesis of Paecilomycins E (1) and F (2), Cochliomycin C (4) and 6-epi-Cochliomycin C (3) is described. The synthesis involves novel route to the synthesis of Paecilomycin E and F and further conversion to Cochliomycin C and 6-epi-Cochliomycin C. Olefin metathesis and base promoted macro lactonization being the key reactions followed by chlorination to achieve target Cochliomycin C and 6-epi-Cochliomycin C.     

De novo consecutive chemo/regioselective IBX mediated oxidation of andrographolide and its derivatives

A new IBX mediated protocol for regio/chemoselective oxidation of andrographolide (1), a labdane diterpenoid isolated from Andrographis paniculata, is developed. After the initial success of this protocol with andrographolide (1) to provide 19-dehydroandrographolide (5) or 3,19-didehydroandrographolide (6) as major products, the procedure was further applied for the oxidation of hydroxyl functionality in andrographolide derivatives, namely 2, 3, 14, and 16. The process was equally suitable on scales of milligram to gram with ease. Deprotection of C-19-OTBDMS in compounds 15 and 18 was achieved using TBDMS-Cl in acetonitrile-water (8:2) system in good yields.     

A tandem synthesis of 3-aroylcoumarinoflavones catalyzed by <Emphasis Type="SmallCaps">l</Emphasis>-proline and their antioxidant activity

A facile, convenient, efficient and high-yielding synthesis of 3-aroylcoumarinoflavones has been developed by the condensation of easily synthesized 7-hydroxy-8-formylflavones and benzoyl acetonitriles in the presence of catalytic amount of l-proline in ethanol reflux. All the synthesized compounds were evaluated for their antioxidant activity. Some of the compounds showed very good activity compared to standard BHT.     

Synthesis and antiproliferative activity of 6,7-aryl/hetaryl coumarins

Two different series of novel analogs of 6,7-aryl/hetaryl coumarins 4a–4h and 8i–8l have been synthesized by using Suzuki–Miyara cross coupling reaction from 4-methyl-2-oxo-2H-chromen-7-yl trifluoro-methanesulfonate and 4-methyl-2-oxo-2H-chromen-6-yl trifluoromethanesulfonate in high yields (70–90%). All synthesized compounds were elucidated by means of IR, ¹H NMR, ¹³C NMR, and MS spectra. The synthesized compounds were tested for antiproliferative activity against different human cancer cell lines (SiHa, MDAMB-231, and PANC-1) and some of products demonstrated the distinctive effect.     

Synthesis of novel substituted pyrano annulated flavones

A simple and efficient one pot method has been developed for the synthesis of some new functionalized pyrano fused flavone derivatives, alkyl 4,8-dioxo-2-phenyl-4,8-dihydropyrano[2,3-f]chromene-10-carboxylates and dialkyl 4-oxo-2-phenyl-4,8-dihydropyrano[2,3-f]chromene-8,9-dicarboxylates, from 7-hydroxy flavones and 7-hydroxy 8-formyl flavones using dialkylacetalynedicarboxylates in the presence of triphenyl phosphine. The structures of all synthesized compounds were elucidated by FT-IR, ¹H and ¹³C NMR and Mass spectral analysis.     

Sc(OTf)<Subscript>3</Subscript> catalyzed synthesis of novel 6-phenyl-6<Emphasis Type="Italic">H</Emphasis>-chromeno[4,3-b]quinolines and evaluation of their cytotoxicity

Novel 6-phenyl-6H-chromeno[4,3-b]quinoline derivatives have been prepared by reaction of 4-chloro-2-phenyl-2H-chromene-3-carbaldehyde with various aromatic amines using 5 mol % of Sc(OTf)3 in acetonitile. This is the first example of one-pot synthesis of 6-phenyl-6H-chromeno[4,3-b]quinoline from 4-chloro-2-phenyl-2H-chromene-3-carbaldehyde at ambient temperature. Preliminary evaluation of cytotoxic activity of these chromeno[4,3-b]quinoline derivatives has been carried out. Some products exhibited anti cancer activity against two carcinoma cell lines A549 and B-16.