A novel hetergeneous mercury salt catalyst stabilized by m-carbaborane can be used and reused for various chemical reactions without leaching the metal.
Novel Hg(OTf)(2)-Catalyzed arylene cyclization was achieved with highly efficient catalytic turnover (up to 200 times). The reaction takes place via protonation of allylic hydroxyl group by in situ formed TfOH of an organomercuric intermediate to generate a cationic species. Subsequent smooth demercuration regenerates the catalyst.
Controlling benzylic functionality and stereochemistry: 2. Synthesis of the pseudopterosin aglycone
作者:Stuart W. McCombie、Brian Cox、Ashit K. Ganduly
DOI:10.1016/s0040-4039(00)71243-3
日期:1991.5
Homologation, cyclisation, and reduction converted the tetralin (2) to the hexahydrophenalenol (8), which was methylated to afford (19) via alkoxide-directed metalation. The degree of stereoselectivity resulting from reactions of (19) and congeners with allylsilane - Lewis acid combinations was markedly dependent upon substitution patterns, whereas Et2AlCN-SnCl4 produced pseudoaxial nitriles. The trimethyl nitrile (24) was elaborated to the pseudopterosin aglycone (4).
975. Totally synthetic steroid hormones. Part I. Oestrone and related œstrapolyenes
作者:G. H. Douglas、J. M. H. Graves、D. Hartley、G. A. Hughes、B. J. McLoughlin、J. Siddall、Herchel Smith
作者:Michael A. Schafroth、Stephan M. Rummelt、David Sarlah、Erick M. Carreira
DOI:10.1021/acs.orglett.7b01346
日期:2017.6.16
systems enabled through the combination of Lewis acid activation and iridium-catalyzedallylicsubstitution is described. The reaction proceeds with branched, allylic alcohols and carbon nucleophiles as well as heteronucleophiles to give a diverse set of ring systems in good yields and with high enantioselectivities. The utility of the method is highlighted by the asymmetric syntheses of erythrococcamides