Palladium-catalysed regio- and stereoselective arylative substitution of γ,δ-epoxy-α,β-unsaturated esters and amides by sodium tetraaryl borates
作者:Yasemin Bilgi、Melih Kuş、Levent Artok
DOI:10.1039/d0ob01226b
日期:——
Palladium-catalysed reactions of γ,δ-epoxy-α,β-unsaturated esters and amides with NaBAr4 reagents proceeded regio- and stereoselectively, producing allylic homoallyl alcohols with aryl-substituents in the allylic position for a wide range of substrates. AsPh3 was found to be a competent ligand for the arylation reaction, whereas phosphine ligand/Lewis acidic organoboron combinations favoured the substitution
Isomerization of Electron-Poor Alkynes to the Corresponding (E,E)-1,3-Dienes Using a Bifunctional Polymeric Catalyst Bearing Triphenylphosphine and Phenol Groups
作者:Patrick Toy、Cathy Kwong、Michael Fu、Henry Law
DOI:10.1055/s-0030-1258576
日期:2010.10
The use of a bifunctional non-cross-linked polystyrene bearing both phosphme and phenol groups tor the organocatalytic isomerization of alkynes bearing electron-withdrawing ester substituents to afford the corresponding (E,E)-dienes in excellent yield and stereoselectivity is described. When polystyrene functionalized with only phosphine groups was used as the catalyst, either low or no yield of the
Organocatalytic Alkyne Isomerizations under Flow Conditions Using Heterogeneous Bifunctional Polystyrene Bearing Phosphine and Phenol Groups
作者:Andreas Kirschning、Patrick Toy、Sascha Ceylan、Henry Law
DOI:10.1055/s-0036-1588589
日期:——
polymer bearing phosphine and phenol groups was developed to catalyze the isomerization of electronically activated alkynes. This organocatalytic process provided the corresponding (E,E)-dienes and was shown to work under both batch and flow conditions. A heterogeneous bifunctional polymer bearing phosphine and phenol groups was developed to catalyze the isomerization of electronically activated alkynes
The first total synthesis of a novel piperidine alkaloid, microcosamine A, is achieved from commercially available d-serine, d-methyl lactate and 1-octyne as starting materials.
(2E,4E)-, (2Z,4E)-, and (2E,4Z)-2,4-Alkadienoates can be synthesized in high yields by the cross-coupling of ethyl (E)-3-bromoacrylate, methyl (E)-3-bromo-2-methylpropenoate, ethyl (Z)-3-bromocrotonate,1-bromo-2-(ethoxycarbonyl)cyclohexene, and 4-bromocoumarin with 2-[(E)-1-alkenyl]-1,3,2-benzodioxaboroles or diisopropyl (Z)-1-hexenylboronate in the presence of 3 mol% of Pd(OAc)2, 6 mol% of PPh3, and 2 equivalents of Na2CO3 or K2CO3 in alcoholic solvents while retaining the original configuration of the double bonds in β-bromo esters and 1-alkenylboronates. Although the coupling reaction with 1-hexenylboronate with (Z)-3-bromoacrylate gave a mixture of ethyl (2Z,4E)- and (2E,4E)-nonadienoates in a ratio of 63 : 37, it was found that the use of bis(diphenylphosphino)ferrocene as a ligand of palladium brought about the stereoselective coupling under mild conditions.