Developing the Saegusa–Ito Cyclisation for the Synthesis of Difluorinated Cyclohexenones
作者:Jonathan M. Percy、Adam W. McCarter、Alan L. Sewell、Nikki Sloan、Alan R. Kennedy、David J. Hirst
DOI:10.1002/chem.201503653
日期:2015.12.21
the turnover of the initial palladium(II) salt, whereas the provision of an oxygen atmosphere ensured more rapid reaction. Annulations required a minimum level of substitution on the chain, but failed when the alkene was substituted. Annelations allowed a range of n,6‐bicyclic systems to be prepared and afforded three products, in which heterocycles were fused to the new cyclohexenone. The least substituted
starting from 4-thianones. Key steps in the synthesis include: (a) reduction of 3-propyl-4-thianone to yield an easily separable isomeric mixture of cis- and trans-3-propyl-4-thianols; and (b) a highly efficient resolution of the particular cis/trans-isomers through a chromatographic separation of their respective esters with (S)-chlorofluoroacetic acid. Subsequent hydrolysis and desulfurization gave
Preparation of 3-Substituted 4-Thianones and Their 1,1-Dioxides via Palladium Mediated Deallyloxycarbonylation
作者:Guy Casy、Alan G. Sutherland、Richard J. K. Taylor、Peter G. Urben
DOI:10.1055/s-1989-27389
日期:——
3-Alkyl-4-thianones 4 (3-alkyl-thiacyclohexan-4-ones) can be conveniently prepared by the alkylation of 3-allyloxycarbonyl-4-thianone (1b) followed by deallyloxycarbonylation mediated by tetrakis (triphenylphosphine)palladium in the presence of morpholine. The corresponding sulphones 9, as well as 2,3-dialkyl 4-thianone derivatives 12 and 13 can be prepared by analogous procedures.
2-Alkyl-3-cyclopentenones were prepared in moderate yields starting from tetrahydrothiopyran-4-one by the one-pot Ramberg–Bäcklund reaction of 6-alkyl-1,4-dioxa-8-thiaspiro[4.5]decane 8,8-dioxides, followed by acid catalyzed de-dioxolanation.
A Comparison of Cyclohexanone and Tetrahydro-4<i>H</i>-thiopyran-4-one 1,1-Dioxide as Pharmacophores for the Design of Peptide-Based Inhibitors of the Serine Protease Plasmin
作者:Fengtian Xue、Christopher T. Seto
DOI:10.1021/jo0508954
日期:2005.10.1
The plasminogen system is important in the proteolytic cascade that facilitates angiogenesis, a process that is essential for tumor growth and metastasis. The serine protease plasmin has a central role in the plasminogen system. This protease acts by degrading several components of the basement membrane and by activating other proteases. Therefore, inhibition of plasmin may be an effective method for blocking angiogenesis and, as a result, inhibiting the growth of primary tumors and secondary metastases. Three pairs of plasmin inhibitors were synthesized to compare the relative potency of inhibitors that are based upon a cyclohexanone or a tetrahydro-4H-thiopyran-4-one 1,1-dioxide nucleus. Compounds 1, 3, and 5 were cyclohexanone-based inhibitors, whereas compounds 2, 4, and 6 were tetrahydro-4H-thiopyran-4-one 1,1-dioxide-based inhibitors. Compounds 5 and 6 are reasonable inhibitors with IC50 values of 25 and 5.5 mu M, respectively. Comparisons of the IC50 values of the three pairs show that the electron-withdrawing sulfone functional group is a beneficial element for the design of plasmin inhibitors. The presence of the sulfone increases inhibitor potency by a factor of 3-5 when compared to inhibitors that are based upon a simple cyclohexanone core.