Chiral Bis(N-sulfonylamino)phosphine- and TADDOL-Phosphite-Oxazoline Ligands: Synthesis and Application in Asymmetric Catalysis
作者:Robert Hilgraf、Andreas Pfaltz
DOI:10.1002/adsc.200404168
日期:2005.1
has been prepared, containing a chiral oxazoline ring and as a second chiral unit a bis(N-sulfonylamino)phosphine group embedded in a diazaphospholidine ring or a cyclic phosphite group derived from TADDOL. These modular ligands are readily synthesized from chiral amino alcohols and chiral 1,2-diamines or TADDOLs. Palladium and iridium complexes derived from these ligands were found to be efficient catalysts
Synthesis and spectroscopic properties of 1,4-diarylbutenynes
作者:Alois H. A. Tinnemans、Wim H. Laarhoven
DOI:10.1039/p29760001104
日期:——
Several new diarylbutenynes have been synthesized and analyses of the n.m.r. and u.v. spectra are described. For planar trans-isomers a conformational preference was found for 1-(α-naphthyl)- but not for 1-(β-naphthyl)-4-arylbutenynes. This difference is also found between compounds with C-1 attached to the α- or β-position of a larger aryl group.
Studies in photochemistry. Part VII. The photocyclisation of some nuclear-substituted stilbenes to substituted phenanthrenes
作者:E. V. Blackburn、C. E. Loader、C. J. Timmons
DOI:10.1039/j39680001576
日期:——
Photocyclodehydrogenation of trans-9-styryl-1,2,3,4,5,6,7,8-octahydroanthracene in cyclohexane solution formed a mixture of 11-butyl- and 11-but-3-enyl-1,2,3,4-tetrahydrochrysene in very small yield, identified by their i.r., u.v., 1H n.m.r., and mass spectra. 2,4,6-Trimethylstilbene photocyclised to 1,3-dimethylphenanthrene with the elimination of a methyl group. 3,3′,5,5′-Tetramethylstilbene formed
在环己烷溶液中反式-9-苯乙烯基-1,2,3,4,5,6,7,8-八氢蒽的光环脱氢反应形成11-丁基-和11-丁-3-烯基-1,2,3的混合物通过其ir,uv,1 H nmr和质谱鉴定的1,4-四氢丙烯收率非常低。2,4,6-三甲基sti光环化为1,3-二甲基菲并消除了甲基。当在环己烷溶液中照射时,3,3',5,5'-四甲基sti形成了2,4,5,7-四甲基菲。类似地,4,4′-二溴-和4,4′-二氰基-sti形成相应的3,6-二取代的菲。
Synthesis and X-ray Analysis of New [5]Helicenes – HMO Calculations on the Photocyclization of the Stilbene Precursors
作者:Christian Stammel、Roland Fröhlich、Christian Wolff、Hans Wenck、Armin de Meijere、Jochen Mattay
The syntheses of the new pentahelicenes 5, 11, 17, 21, and 28 with various substituents are described. In the case of 2,13-dicyano-[5]helicene (11) optical resolution was achieved by HPLC using a column packed with gamma-cyclodextrin. However, the enantiomers racemized within a few hours. On the other hand, the enantiomers of 28 turned out to be stable after separation on triacetylcellulose using MPLC
Electrophilic aromatic substitution. Part 22. The nitration of some reactive aromatics in methanesulphonic acid, and the question of positional selectivity in encounter rate nitrations of substituted naphthalenes and 1,2-diphenylethanes
作者:James W. Barnett、Roy B. Moodie、Kenneth Schofield、Peter G. Taylor、John B. Weston
DOI:10.1039/p29790000747
日期:——
Nitrations in aqueous methanesulphonic acid are shown by the steep acidity dependence of the rate constants, the identification of a kinetic form zeroth-order in the concentration of the aromatic, and the existence of a limiting rate constant identified as the encounter rate constant, most probably to involve the nitronium ion.