Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.The authors thank the National Science Center (Cracow, Poland) for generous financial support (Grant Maestro-3 (Dec- 2012/06/A/ST5/00219). Skilful performance of microanalyses by Ms Hanna Jatczak and Ms Agnieszka Cieślińska (University of Łódź) is gratefully acknowledge

Synthesis, Selected Transformations, and Biological Activity of Alkoxy Analogues of Lepidilines A and C

Condensation of diacetyl monooxime with formaldimines derived from alkoxyamines in glacial acetic acid at room temperature leads to corresponding 2-unsubstituted imidazole N-oxides bearing an alkoxy substituent at the N(1) atom of the imidazole ring. Subsequent O-benzylation afforded, depending on the type of alkylating agent, either symmetric or nonsymmetric alkoxyimidazolium salts considered as structural analogues of naturally occurring imidazole alkaloids, lepidilines A and C. Some of the obtained salts were tested as precursors of nucleophilic heterocyclic carbenes (NHCs), which in situ reacted with elemental sulfur to give the corresponding N-alkoxyimidazole-2-thiones. The cytotoxic activity of selected 4,5-dimethylimidazolium salts bearing either two benzyloxy or benzyloxy and 1-adamantyloxy groups at N(1) and N(3) atoms was evaluated against HL-60 and MCF-7 cell lines using the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Notably, in two cases of alkoxyimidazolium salts, no effect of the counterion exchange (Br− → PF6−) on the biological activity was observed

Matrix isolation and spectroscopic properties of the methylsulfinyl radical CH3(O)S˙

Publikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2013 finansowanego przez Uniwersytet ŁódzkiThe atmospherically highly relevant methylsulfinyl radical CH3(O)S˙ was generated thermally under flash pyrolysis conditions and isolated in Ar matrices at 10 K; the allyl radical is a byproduct. CH3(O)S˙ and its D3- and 13C-isotopologues were characterized through the excellent agreement between experimental and computed IR and UV/Vis spectra