Step-wise and one-pot synthesis of highly substituted conjugated trienes from 2-oxobenzo[h]chromenes/2H-pyran-2-ones

A mild and efficient route for the synthesis of conjugated trienes via nitroethane-mediated ring contraction of 2-oxobenzo[h]chromenes/2H-pyran-2-ones followed by decarboxylative rearrangement of the obtained spirobutenolides and butenolides is described. The (E)-isomer of trienes was obtained by step-wise and one-pot approaches from 2-oxobenzo[h]chromenes. Butenolides 4a-l as new substrates have been developed for the construction of trienes. The mixture of the (E)- and (Z)-isomers of spirobutenolides undergoes decarboxylative rearrangement in the presence of sodium ethoxide as a base to yield the (E)-isomer of trienes, while the (E)-isomer of butenolides reacts to give a mixture of (2E,4E)- and (2E,4Z)-isomers of trienes in an almost steady ratio of 45 : 55 or 1 : 1.2. The structure and geometry of the obtained butenolides and trienes were confirmed by single-crystal X-ray analysis.

Synthesis of indolizines from pyridinium 1,4-zwitterionic thiolates and α-functionalized bromoalkanes via a stepwise [(5+1)−1] pathway

Pyridinium 1,4-zwitterionic thiolates were applied to accessing indolizines via a sequence of annulation, oxidation and ring-contraction/desulfuration.

Crystal Structure and Computational Study on Methyl-3-Aminothiophene-2-Carboxylate

Methyl-3-aminothiophene-2-carboxylate (matc) is a key intermediate in organic synthesis, medicine, dyes, and pesticides. Single crystal X-ray diffraction analysis reveals that matc crystallizes in the monoclinic crystal system P21/c space group. Three matc molecules in the symmetric unit are crystallographically different and further linked through the N–H⋯O and N–H⋯N hydrogen bond interactions along with weak C–H⋯S and C–H⋯Cg interactions, which is verified by the three-dimensional Hirshfeld surface, two-dimensional fingerprint plot, and reduced density gradient (RDG) analysis. The interaction energies within crystal packing are visualized through dispersion, electrostatic, and total energies using three-dimensional energy-framework analyses. The dispersion energy dominates in crystal packing. To better understand the properties of matc, electrostatic potential (ESP) and frontier molecular orbitals (FMO) were also calculated and discussed. Experimental and calculation results suggested that amino and carboxyl groups can participate in various inter- and intra-interactions.

Molecular Insights into the Interaction of RONS and Thieno[3,2-c]pyran Analogs with SIRT6/COX-2: A Molecular Dynamics Study

SIRT6 and COX-2 are oncogenes target that promote the expression of proinflammatory and pro-survival proteins through a signaling pathway, which leads to increased survival and proliferation of tumor cells. However, COX-2 also suppresses skin tumorigenesis and their relationship with SIRT6, making it an interesting target for the discovery of drugs with anti-inflammatory and anti-cancer properties. Herein, we studied the interaction of thieno[3,2-c]pyran analogs and RONS species with SIRT6 and COX-2 through the use of molecular docking and molecular dynamic simulations. Molecular docking studies revealed the importance of hydrophobic and hydrophilic amino acid residues for the stability. The molecular dynamics study examined conformational changes in the enzymes caused by the binding of the substrates and how those changes affected the stability of the protein-drug complex. The average RMSD values of the backbone atoms in compounds 6 and 10 were calculated from 1000 ps to 10000 ps and were found to be 0.13 nm for both compounds. Similarly, the radius of gyration values for compounds 6 and 10 were found to be 1.87 ± 0.03 nm and 1.86 ± 0.02 nm, respectively. The work presented here, will be of great help in lead identification and optimization for early drug discovery.

Base controlled diverse reactivity of allyl cyanide for synthesis of multi-substituted benzenes

A base controlled regioselective 1,6-cyanoallylation of suitably functionalized 2H-pyran-2-ones has been demonstrated for the synthesis of various multi-substituted benzenes through a tandem process.

Chemoselective synthesis of m-teraryls through ring transformation of 2H-pyran-2-ones by 2-(1-arylethylidene)-malononitriles

Base mediated chemoselective synthesis of m-teraryls was carried out by the reaction of 2H-pyran-2-ones and 2-(1-arylethylidene)malononitriles.

Base-Promoted Selective Synthesis of 2H-Pyranones and Tetrahydronaphthalenes via Domino Reactions

A highly efficient domino protocol has been developed for the synthesis of 6-aryl-4-(methylthio/amine-1-yl)-2-oxo-2H-pyran-3-carbonitriles and 4-aryl-2-(amine-1-yl)-5,6,7,8-tetrahydronaphthalene-1-carbonitriles from simple and readily available α-aroylketene dithioacetals, malononitrile, secondary amines, and cyclohexanone. This elegant domino process involved consecutive addition-elimination, intramolecular cyclization, and ring opening and closing sequences. Notably, in situ generated 2-imino-4-(methylthio/amine-1-yl)-6-aryl-2H-pyran-3-carbonitrile plays multiple roles in the construction of various novel polyaromatic hydrocarbons.

One-pot and step-wise synthesis of thieno[3,2-c]pyridin-4-ones

Both one pot and step wise synthesis of methyl 3,5-diaminothieno[3,2-c]pyridin-4-one-2-carboxylates6have been delineated by the reaction of 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles3, methyl mercaptoacetate and hydrazine hydrate.