Search Results (2)

The stereoselective synthesis of bicyclo[3.2.0]heptanes via an anion radical [2+2] photocycloaddition of aryl bis-enone derivatives was investigated. By employing chiral oxazolidinone auxiliaries bound to aryl bis-enone substrates, enantioenriched, highly substituted bicyclo[3.2.0]heptanes have been synthesized. The reaction, mediated by Eosin Y and promoted by LiBr under visible light irradiation, has been studied both experimentally and computationally to elucidate the mechanism and stereoselective outcomes. The process proceeds via a syn-closure pathway, leading to the formation of the corresponding cis-anti diastereoisomers as major products isolated and characterized by X-ray analysis; DFT calculations provided useful insights and computational support which allow a plausible reaction mechanism to be proposed that agrees with the collected experimental data. Full article

A series of 3,5-bis(benzylidene)-4-piperidones 2a–u were prepared as candidate cytotoxic agents. In general, the compounds are highly toxic to human gingival carcinoma (Ca9-22), human squamous carcinoma-2 (HSC-2) and human squamous carcinoma-4 (HSC-4) neoplasms, but less so towards non-malignant human gingival fibroblast (HGF), human periodontal ligament fibroblast (HPLF) and human pulp cells (HPC), thereby demonstrating tumour-selective toxicity. A further study revealed that most of the compounds in series 2 were more toxic to the human Colo-205 adenocarcinoma cell line (Colo-205), human HT29 colorectal adenocarcinoma cells (HT-29) and human CEM lymphoid cells (CEM) neoplasms than towards non-malignant human foreskin Hs27 fibroblast line (Hs27) cells. The potency of the cytotoxins towards the six malignant cell lines increased as the sigma and sigma star values of the aryl substituents rose. Attempts to condense various aryl aldehydes with 2,2,6,6-tetramethyl-4-piperidone led to the isolation of some 1,5-diaryl-1,4-pentadien-3-ones. The highest specificity for oral cancer cells was displayed by 2e and 2r. In the case of 2r, its selective toxicity exceeded that of doxorubicin and melphalan. The enones 2k, m, o have the highest SI values towards colon cancer and leukemic cells. Both 2e,r inhibited mitosis and increased the subG1 population (with a transient increase in G2/M phase cells). Slight activation of caspase-3, based on the cleavage of poly(ADP-ribose)polymerase (PARP) and procaspase 3, was detected. Full article