Rajesh G. Kalkhambkar

Triflic Anhydride: A Mild Reagent for Highly Efficient Synthesis of 1,2-Benzisoxazoles, Isoxazolo, and Isothiazolo Quinolines Without Additive or Base

Abstract The synthetic utility of trifluoromethanesulphonic anhydride (triflic anhydride, TA) without additive or base for the high-yielding synthesis of a wide variety of 1,2-benzisoxazoles from 2-hydroxyaryl aldoximes and ketoximes under mild conditions has been carried out for the first time. As a continuation of our study, syntheses of isoxazolo and isothiazolo quinolones have also been demonstrated using triflic anhydride under similar conditions. This method is simple and has benefits from the easy way to isolate the products in excellent yields. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT

Synthesis and biological studies of some new acrylic acid ethyl esters of quinolinone

A series of new acrylic acid ethyl esters of quinolinones were synthesized from 4-(bromomethyl)quinolinones and screened for in vitro antimicrobial and in vivo analgesic and anti-inflammatory activities. Most of the compounds with chloro substitution at the C-6 or C-7 position in the quinolinone moiety and a methoxy group in the aryloxy moiety showed potent antibacterial and antifungal activities when compared with non-halogenated quinolinones and the quinolinones bearing a CH3 at the C-8 position. In a pharmacological evaluation, the halogen substitution at the C-6 or C-7 position in quinolinones was found to enhance both analgesic and anti-inflammatory activities of the molecule when compared with a simple unsubstituted (non-halogenated) quinolinone. The structures of all newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and FAB-MS.Graphical abstract

(Z)-2-[2-(4-Methyl­benzyl­idene)hydrazin­yl]pyridine

Molecules of the title compound, C13H13N3, are essentially planar (r.m.s. deviation for all non-H atoms = 0.054 Å). The dihedral angle between the two aromatic rings is 6.33 (5)°. In the crystal, pairs of centrosymmetrically related molecules are linked through N—H⋯N hydrogen bonds, forming N—H⋯N dimers with graph-set motif R22(8).

N-(2-Chloro­quinolin-3-ylmethyl­ene)aniline

The title compound, C16H11ClN2, displays a trans configuration across the C=N bond and a transoid arrangement across the quinoline ring and the azomethine C atom. This arrangement facilitates C—H⋯Cl interactions. The packing in the crystal structure is due to intermolecular C—H⋯π and Cl⋯π (3.52 and 3.84 Å) interactions. The dihedral angle between the least-squares planes of 2-chloroquinoline and phenylamine is 16.61 (2)°.

Highly efficient synthesis of amides from ketoximes using trifluoromethanesulphonic anhydride

Trifluoromethanesulphonic anhydride (triflic anhydride: TA) has been successfully used as a reagent for Beckmann rearrangement in the conversion of a variety of ketoximes into amides without any additive or base. This reagent works well for the synthesis of a library of amides with excellent yields.

8-[(Hydrazinyl-idene)meth-yl]-4-methyl-2-oxo-2H-chromen-7-yl 4-methyl-benzene-sulfonate.

In the title compound, C18H16N2O5S, the coumarin ring system is nearly planar, with a maximum out-of-plane deviation of 0.078 (1) Å (r.m.s. deviation = 0.046 Å). The dihedral angle between the coumarin ring system and the toluene ring (r.m.s. deviation = 0.004 Å) is 2.77 (1)°. The crystal packing is stabilized by C—H⋯O and N—H⋯O intermolecular hydrogen bonds generating C(8), C(9) and C(11) chains and R 2 2(14), R 2 2(23) and R 4 3(13) ring graph sets.

(E)-Ethyl 2-cyano-3-(1H-pyrrol-2-yl)acrylate.

All the non-H atoms of the title compound, C10H10N2O2, are nearly in the same plane with a maximum deviation of 0.093 (1) Å. In the crystal, adjacent molecules are linked by pairs of intermolecular N—H⋯O hydrogen bonds, generating inversion dimers with R 2 2(14) ring motifs.

Ethyl 4-(3-bromo­phen­yl)-6-methyl-2-oxo-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

In the title compound, C14H15BrN2O3, the dihydropyrimidinone ring adopts a boat conformation. In the crystal, adjacent molecules are linked through N—H⋯O hydrogen bonds forming an R22(8) ring motif and generating a zigzag chain extending in [010].

Synthetic and biological studies on mono- and bis-methylene-bridged heterocyclic sulfides and sulfones of carbostyrils

A series of new sulfides and sulfones of carbostyrils were synthesized and tested for their in vitro antimicrobial and in vivo analgesic activities. The results of a bioassay showed that these newly synthesized compounds exhibit potential antibacterial and antifungal activities. The chloro substitution at C-6 and C-7 positions of carbostyrils was found to enhance the antimicrobial activity. Similarly, halogen-substituted sulfones were found to possess potent analgesic activities. All the newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, ESI-MS and FAB-MS.

Highly Efficient Synthesis of 1,3-Dioxanes via Prins Reaction in Brønsted-Acidic Imidazolium Ionic Liquid

Abstract The high-yielding synthesis of a wide variety of 1,3-dioxanes via the Prins reaction under mild conditions has been demonstrated using Brønsted-acidic imidazolium ionic liquid [bmim(SO3H)][OTf] or bmimOTf. The use of ionic liquid makes this synthesis simple, convenient, cost-effective, and environmentally friendly. Furthermore, bmimOTf was conveniently separated from the products and can be easily recycled for the Prins reaction with excellent yields. This method works well with a variety of aliphatic aldehydes including formaldehyde, acetaldehyde, propionaldehyde, and cyclohexanecarboxaldehyde. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT