A novel mononuclear Fe(iii) mono(terpyridine) complex having labile solvent ligands and its catalytic activityElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/dt/b2/b208413a/
作者:Andreas Tschöp、Andreas Marx、Anakallil R. Sreekanth、Christoph Schneider
DOI:10.1002/ejoc.200601101
日期:2007.5
The scandium-bipyridine-catalyzed ring-opening of meso-epoxides with aliphatic alcohols has been studied. Aromatic epoxides were ring-opened with >90 % ee furnishing valuable 1,2-diol monoethers in typically good yields whereas aliphatic epoxides gave rise to moderate enantioselectivities. The catalyst loading may be lowered to 2–5 mol-% with only marginal effects on yield and enantioselectivity. A
The acid catalyzed ethanolysis of trans-2,3-diphenyloxirane was examined in a wide variety of binary ethanolic solvent systems. The reaction proceeded with 26% retention and 74% inversion of configuration in pure ethanol at 50 °C. The dilution of ethanol by hexane or benzene produced almost no change in stereochemistry of the ethanolysis. The addition of acetonitrile, nitromethane, or sulfolane to the ethanolic solution resulted in increased degrees of retention. In binary ethanolic mixtures containing DMSO, DMF, or HMPA, increased ratios of inverted product were obtained. The steric course of the ethanolysis could be controlled from 85% retention–15% inversion (CH3NO2:ethanol=20:2 by volume) to 10% retention–90% inversion (HMPA: ethanol=10:12) by the choice of co-solvent. The results are discussed in terms of the solvation-shell concept.