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
Ir-catalysed allylicalkylations of enantiomerically enriched monosubstituted allylic acetates proceed with up to 87% retention of configuration using P(OPh)3 as ligand. High regio- and enantioselectivity of up to 86% ee in asymmetric allylicalkylations of achiral or racemic substrates is achieved with monodentate phosphorus amidites as ligands. Lithium N-tosylbenzylamide was identified as a suitable
使用 P(OPh)3 作为配体,Ir 催化的烯丙基烷基化对映体富集的单取代烯丙基乙酸酯的构型保留率高达 87%。以单齿磷酰胺作为配体,在非手性或外消旋底物的不对称烯丙基烷基化中实现了高达 86% ee 的高区域和对映选择性。N-tosylbenzylamide 锂被确定为适合烯丙基胺化的亲核试剂。特别重要的是使用氯化锂作为添加剂,通常会导致对映选择性增加。通过 X 射线晶体结构分析和光谱数据对两种 (π-烯丙基) IrIII 配合物进行了表征。
Chiral Bis(<i>N</i>-tosylamino)phosphine- and TADDOL-Phosphite-Oxazolines as Ligands in Asymmetric Catalysis
作者:Robert Hilgraf、Andreas Pfaltz
DOI:10.1055/s-1999-2939
日期:1999.11
A series of P,N-ligands containing a chiral oxazoline ring and a chiral bis(N-tosylamino)phosphine group derived from a 1,2-diamine or a chiral cyclic phosphite group derived from TADDOL has been prepared. These compounds proved to be efficient ligands for enantiocontrol of palladium-catalyzed allylic alkylations and iridium-catalyzed hydrogenations of olefins.
Simplified procedures for the Ir-catalyzed asymmetric allylicalkylation reaction are described that often allow substitution products to be obtained with ≥99% ee. Applications to syntheses of important chiral building blocks, such as the Taniguchi lactone and dimethyl 2-vinylcyclopropane-1,1 -dicarboxylate, are presented.
描述了 Ir 催化的不对称烯丙基烷基化反应的简化程序,通常允许获得≥99% ee 的取代产物。介绍了重要手性构件的合成应用,如谷口内酯和 2-乙烯基环丙烷-1,1-二羧酸二甲酯。
Remarkable Ligand Effects in Regioselective Palladium-Catalysed Allylic Substitution Reactions
The use of tricyclohexylphosphine (and related phosphines) in palladium-catalysedallylicsubstitution reactions enables the selective conversion of branched allylic acetates into the branched substitution products (up to 120:1 regioselectivity). Linear allylic acetates do not show the same selectivity for the branched substitution products, thereby demonstrating a memory effect.