A Convenient Synthesis of Novel Isoxazolidine and Isoxazole Isoquinolinones Fused Hybrids

Isoxazolidine, isoxazole, and isoquinolinone rings are present in the structure of several natural products and/or pharmaceutically interesting compounds. In this work, facile and efficient pathways have been developed for the preparation of fused frameworks bearing those heterocycles. The successful approaches for both isoxazolidine/isoquinolinone and isoxazole/isoquinolinone hybrid syntheses relied initially on 1,3-dipolar cycloadditions of nitrones and nitrile oxides to indenone and 2-propargylbenzamide, respectively. The construction of the isoquinolinone lactam system followed by performing a selective Schmidt reaction for isoxazolidine derivatives (two steps overall), whereas the isoxazole lactams were reached via an Ullmann-type cyclisation (three steps overall). Key observations were made regarding the stereo- and regioselectivities of the reactions employed, and small libraries of the targeted hybrids were prepared, demonstrating the general applicability of these strategies.

Schmidt Reaction ofE-3-Benzylidenechromanones andE-3-Benzylidenethiochromanones

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

Synthesis, 3D-QSAR, and structural modeling of benzolactam derivatives with binding affinity for the D(2) and D(3) receptors

A series of 37 benzolactam derivatives were synthesized, and their respective affinities for the dopamine D(2) and D(3) receptors evaluated. The relationships between structures and binding affinities were investigated using both ligand-based (3D-QSAR) and receptor-based methods. The results revealed the importance of diverse structural features in explaining the differences in the observed affinities, such as the location of the benzolactam carbonyl oxygen, or the overall length of the compounds. The optimal values for such ligand properties are slightly different for the D(2) and D(3) receptors, even though the binding sites present a very high degree of homology. We explain these differences by the presence of a hydrogen bond network in the D(2) receptor which is absent in the D(3) receptor and limits the dimensions of the binding pocket, causing residues in helix 7 to become less accessible. The implications of these results for the design of more potent and selective benzolactam derivatives are presented and discussed.

The Application of the Schmidt Reaction and Beckmann Rearrangement to the Synthesis of Bicyclic Lactams: Some Mechanistic Considerations

The syntheses of some methoxy-substituted bicyclic lactams, of the types 3 and 4, are reported employing two different conditions for the Schmidt reaction of appropriate ketones and employing two different conditions for the Beckmann rearrangement of the corresponding ketoximes. The alkyl to aryl migration ratios of the reactions were determined by high-performance liquid chromatography analysis of the reactions. The mechanisms of the reactions reported are discussed, some limitations of the reported mechanisms identified, and an alternative mechanism proposed in light of the outcomes of the various reactions. Application of the Schmidt reaction and Beckmann rearrangement was used for the synthesis of some chloro bicyclic lactams, of the types 3 and 4.

Synthesis, binding affinity and SAR of new benzolactam derivatives as dopamine D3 receptor ligands

A series of new benzolactam derivatives was synthesized and the derivatives were evaluated for their affinities at the dopamine D(1), D(2), and D(3) receptors. Some of these compounds showed high D(2) and/or D(3) affinity and selectivity over the D(1) receptor. The SAR study of these compounds revealed structural characteristics that decisively influenced their D(2) and D(3) affinities. Structural models of the complexes between some of the most representative compounds of this series and the D(2) and D(3) receptors were obtained with the aim of rationalizing the observed experimental results. Moreover, selected compounds showed moderate binding affinity on 5-HT(2A) which could contribute to reducing the occurrence of extrapyramidal side effects as potential antipsychotics.

Novel Formation of Spirocyclic Oxazolines in the Reaction of Some (E)-3-(4-methoxybenzylidene)Flavanones with NaN3/c.H2SO4-HOAc

On treatment with NaN3/c.H2SO4-HOAc, some (E)-3-(4-methoxybenzylidene) flavanones yield a new type of flavonoid-derived spirocyclic oxazolines in moderate yield. A plausible mechanism for formation of these products is suggested.

Novel acetylcholinesterase inhibitor as increasing agent on rhythmic bladder contractions: SAR of 8-{3-[1-(3-fluorobenzyl)piperidin-4-yl]propanoyl}-1,2,5,6-tetrahydro-4H-pyrrolo[3,2,1-ij]quinolin-4-one (TAK-802) and related compounds

As part of an on-going investigation to develop an increasing agent on rhythmic bladder contractions, 1-aryl-3-(1-benzylpiperidin-4-yl)propanones were synthesized and examined as noncarbamate acetylcholinesterase (AChE) inhibitors. Among compounds with various aryl groups, 1,2,5,6-tetrahydro-4H-pyrrolo[3,2,1-ij]quinolin-4-one derivative 9c was found to possess a potent AChE inhibition activity with an IC(50) value of 1.3nM. The compound 9c increased rhythmic bladder contractions in Guinea pigs and rats without affecting the basal intravesical pressure, which suggests that 9c may be useful for the treatment of voiding dysfunction caused by detrusor underactivity.