Generality and mechanism of homobenzylic-homoallylic hydrogenolysis of 5-aryl-4,5-dihydro-1,3-dioxepins
作者:Kiyohiro Samizu、Kunio Ogasawara
DOI:10.1016/0040-4039(94)80030-8
日期:1994.10
Birch reduction of several 5-aryl-4,5-dihydro-1,3-dioxepins gave rise to 3-arylbutanal in moderate to good yields by hydrogenolytic cleavage of the homobenzylic-homoallylic carbonoxygen bond when the benzylic-allylic carbon is tertiary. However, the reaction did not take place when the benzylic-allylic carbon is quaternary. Moreover, the reaction was found to proceed with complete racemization at
Screening of a Modular Sugar-Based Phosphite–Oxazoline Ligand Library in Asymmetric Pd-Catalyzed Heck Reactions
作者:Yvette Mata、Oscar Pàmies、Montserrat Diéguez
DOI:10.1002/chem.200601714
日期:2007.4.16
We have synthesised a library of phosphite-oxazolineligands derived from readily available D-glucosamine. These ligands have been successfully screened in the palladium-catalysed Heckreaction of several substrates with high regio- (up to 99 %) and enantioselectivities (ee's up to 99 %) as well as with improved activities under standard thermal conditions. The results indicate that the catalytic performance
An efficient phosphorus-containing oxazoline ligand derived from cis -2-amino-3,3-dimethyl-1-indanol: application to the palladium-catalyzed asymmetric Heck reaction
Enantiopure 2-[2-(diphenylphosphino)phenyl]oxazoline, derived from a non-natural chiral aminoalcohol, cis-2-amino-3,3-dimethyl-1-indanol, was found to be an efficientligand for the palladium-catalyzed asymmetric Heckreaction.
[chemical reaction: see text]. A series of phosphite-oxazoline ligands, derived from readily available D-glucosamine, have been used for the first time in the palladium-catalyzed Heckreaction of several substrates with high regio- and enantioselectivities (ee's up to 99%) and improved activities in standard conditions.
Palladium complexes with chiral phosphinooxazoline ligands are efficient catalysts for enantioselective Heck reactions with aryl or alkenyl triflates and cyclic alkenes. In the arylation and alkenylation of 1,2-dihydrofuran, cyclopentene, 2,3-dihydro-4H-pyran, 4,7-dihydro-1,3-dioxepin, and N-methoxycarbonyl-2,3-dihydropyrrole high yields and good to excellent enantioselectivities have been obtained. In contrast to analogous (BINAP)Pd-catalyzed reactions, isomerization of the products by C-C double bond migration was essentially not observed.