A Rapid, Efficient and Green Method for Synthesis of 3,3'-Arylmethylene-bis-4-hydroxycoumarins without Use of any Solvent, Catalyst or Solid Surface

Abstract: A rapid, efficient and green methodology has been developed for the synthesis of 3,3'-arylmethylene-bis-4-hydroxycoumarins by microwave assisted condensation of aromatic aldehydes and 4-hydroxycoumarin without use of any solvent, catalyst or solid surface

(E)-2-(2-Pyridinyl)-3-(2-pyridinylmethylene)chromanone, a 1:2 condensation product of 2′-hydroxyacetophenone and pyridine-2-aldehyde, showing some interesting properties

805-810An efficient synthesis of (E)-2-(2-pyridinyl)-3-(2-pyridinylmethylene)chromanone has been done by treatment of 2′-hydroxyacetophenone and pyridine-2-aldehyde in aqueous methanolic KOH. The compound has been obtained as crystalline precipitate from the reaction medium, which was suitable for spectral analysis and X-ray crystallographic study. It possesses an interesting intramolecular hydrogen bonding between the C2-H and the nitrogen of 2-pyridinylmethylene moiety. At room temperature, it is stable for months in the crystalline state, but in CDCl3 solution it gradually changes to the endocyclic isomer 2-(2-pyridinyl)-3-(2-pyridinylmethyl)chromone. From analysis of the X-ray crystallographic data and DFT studies, possible explanations have been given for the stability of the compound in the crystalline state and its isomerization in solution

An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

A rapid, efficient, and solvent-free methodology for synthesis of exocyclic α,β-unsaturated ketones of the categories E-3-arylidene-4-chromanones, E-2-arylidene-1-tetralones, E-2-arylidene-1-indanones, E-3-cinnamylidene-4-chromanones, E-2-cinnamylidene-1-tetralones, E-2-cinnamylidene-1-indanones, α,α′-(E,E)-bis(arylidene)-cycloalkanones, and α,α′-(E,E)-bis(cinnamylidene)-cycloalkanones has been developed through cross-aldol condensation of the constituent cyclic ketones and aldehydes by microwave irradiation over anhydrous potassium carbonate. However, for condensation of 1-thio-4-chromanones with aromatic aldehydes by this method, the initially formed exocyclic α,β-unsaturated ketone has been found to undergo isomerization yielding 3-(arylmethyl)thiochromones

Facile Condensation of Aromatic Aldehydes with Chroman-4-ones and 1-Thiochroman-4-ones Catalysed by Amberlyst-15 under Microwave Irradiation Condition

Different aromatic aldehydes and cinnamaldehyde undergo cross-aldol condensation with chroman-4-ones and1-thiochroman-4-ones in the presence of amberlyst-15 under microwave irradiation in solvent free condition to afford rapidly the corresponding E-3-arylidene and E-3-cinnamylidene derivatives, respectively, in high yield. This process is simple, efficient and environmentally benign

Synthesis, characterization and DNA interaction studies of new triptycene derivatives

A facile and efficient synthesis of a new series of triptycene-based tripods is being reported. Using 2,6,14- or 2,7,14-triaminotriptycenes as synthons, the corresponding triazidotriptycenes were prepared in high yield. Additionally, we report the transformation of 2,6,14- or 2,7,14-triaminotriptycenes to the corresponding ethynyl-substituted triptycenes via their tribromo derivatives. Subsequently, derivatization of ethynyl-substituted triptycenes was studied to yield the respective propiolic acid and ethynylphosphine derivatives. Characterization of the newly functionalized triptycene derivatives and their regioisomers were carried out using FTIR and multinuclear NMR spectroscopy, mass spectrometry, and elemental analyses techniques. The study of the interaction of these trisubstituted triptycenes with various forms of DNA revealed interesting dependency on the functional groups of the triptycene core to initiate damage or conformational changes in DNA

Schmidt Reaction of E-3-Benzylidenechromanones and E-3-Benzylidenethiochromanones

On treatment with NaN3/c. H2SO4-HOAc or NaN3/TFA, E-3-benzylidenechromanones are mostly converted to E-β-aminobenzylidenechromanones while E-3-benzylidenethiochromanones are converted to 3-benzoylthiochromones. A structurally new type of product has been isolated for the reaction of E-3-benzylidene-4′-methoxychromanone with NaN3/TFA. Mechanistic paths have been suggested for formation of the products