142169-23-1Relevant articles and documents
Enantioselective Hydroformylation of 1-Alkenes with Commercial Ph-BPE Ligand
Yu, Zhiyong,Eno, Meredith S.,Annis, Alexandra H.,Morken, James P.
, p. 3264 - 3267 (2015/07/15)
A rhodium complex, in conjunction with commercially available Ph-BPE ligand, catalyzes the branch-selective asymmetric hydroformylation of 1-alkenes and rapidly generates α-chiral aldehydes. A wide range of terminal olefins including 1-dodecene were examined, and all delivered high enantioselectivity (up to 98:2 er) as well as good branch:linear ratios (up to 15:1). (Chemical Equation Presented).
Synthesis of (+)-discodermolide by catalytic stereoselective borylation reactions
Yu, Zhiyong,Ely, Robert J.,Morken, James P.
, p. 9632 - 9636 (2014/10/15)
The marine natural product (+)-discodermolide was first isolated in 1990 and, to this day, remains a compelling synthesis target. Not only does the compound possess fascinating biological activity, but it also presents an opportunity to test current methods for chemical synthesis and provides an inspiration for new reaction development. A new synthesis of discodermolide employs a previously undisclosed stereoselective catalytic diene hydroboration and also establishes a strategy for the alkylation of chiral enolates. Furthermore, this synthesis of discodermolide provides the first examples of the asymmetric 1,4-diboration of dienes and borylative diene-aldehyde couplings in complex-molecule synthesis. Borylation-based synthesis: The development of a strategy for stereocontrol in catalytic diene hydroboration enables the synthesis of a critical building block for the assembly of (+)-discodermolide. Combined with asymmetric catalytic diboration, hydroformylation, and borylative aldehyde-diene coupling reactions, (+)-discodermolide could then be prepared from simple hydrocarbon-based building blocks.
Oxidation of olefins by palladium(II). 18. Effect of reaction conditions, substrate structure and chiral ligand on the bimetallic palladium(II) catalyzed asymmetric chlorohydrin synthesis
El-Qisairi, Arab K,Qaseer, Hanan A,Henry, Patrick M
, p. 168 - 176 (2007/10/03)
The effect of electronic factors, solvent composition, identity of the chiral bidentate, and olefin structure on the yields and enantioselectivities of the asymmetric chlorohydrin synthesis were investigated. Electronic effects on the chlorohydrin reaction were tested by oxidation of phenyl allyl ether p-substituted by H, Cl, CH3O and CN. All species gave same similar yields and enantioselectivities indicating that electronic effects are not important. Varying the solvent composition of the THF-H2O mixtures indicated that the optimal solvent mixture contains more than 85% THF. Variation of added [Cl-] indicated that the added chloride had to be greater than 0.2 M for high yields and %ee's. Under ideal conditions the enantioselectivities of the chlorohydrins from the phenyl allyl ethers were more than 90%ee. Vinylacetic acid, methyl acrylate and trans-cinnamaldehyde were unreactive under the usual reaction conditions while 2-hydroxy-3-butene and allyl acetate give lower %ee's than did the phenyl allyl ethers. Styrene and α- methylstryrene gives comparable rates of reactions but the %ee's were lower with the latter. (2,6-Diisopropyl)phenyl allyl ether and 2- hydroxy-3-butene give high %ee's indicating that steric hindrance was not a major factor. All of the chiral bridging ligands tested gave satisfactory results except for DACH. A strange case was BZOX which did not give any induction at all. Structural studies showed the ligands are not large enough to bridge both Pd(II) in the bimetallic catalyst so one Pd(II) contained both ligand groups of the bidentate ligand and was thus unreactive. The other Pd(II) of the dimer was reactive but did not contain any chiral ligands to induce optical activity.
Protection of carbonyl compounds as 1,5-dihydro-2,4-benzodioxepines over HZSM-5 zeolite, as a reusable catalyst
Tajbakhsh,Mohajerani,Heravi
, p. 135 - 138 (2007/10/03)
A mild and effecient catalytic method for acetalization of carbonyl compounds as 1, 5-dihydro-2, 4-benzodioxepines with benzene 1, 2-dimethanol using acidic HZSM-5 zeolite as reusable catalyst is described.
Asymmetric dihydroxylation of acrolein acetals: Synthesis of stable equivalents of Enantiopure glyceraldehyde and glycidaldehyde
Oi, Ryu,Sharpless, K. Barry
, p. 2095 - 2098 (2007/10/02)
Asymmetric dihydroxylation (ADH) of acrolein acetals afforded optically active glyceraldehyde equivalents. Enantiopure 3-(1,2-dihydroxyethyl)-1,5-dihydro-3H-2,4-benzodioxepine 3, a protected glyceraldehyde, was obtained from the corresponding acrolein acetal 2 by ADH and subsequent recrystallization. Enantiopure 3-(1,2-epoxyethyl)-1,5-dihydro-3H-2,4-benzodioxepine 5, a protected glycidaldehyde, was produced in two steps from 3.
