Metal-Free Catalytic Boration at the β-Position of α,β-Unsaturated Compounds: A Challenging Asymmetric Induction
作者:Amadeu Bonet、Henrik Gulyás、Elena Fernández
DOI:10.1002/anie.201001198
日期:——
Enantiomerically enriched secondary organoboronates containing β‐carbonyl functional groups have been prepared using an unprecedented organocatalytic system (see scheme). The use of chiral tertiary phosphorus compounds induced ee values of up to 95 % in the absence of transition metals.
Reductive biotransformation of carbonyl compounds—application of fungus, Geotrichum sp. G38 in organic synthesis
作者:Gu Jian-Xin、Li Zu-Yi、Lin Guo-Qiang
DOI:10.1016/s0040-4020(01)87947-3
日期:1993.6
The microbial transformation of 2- and 3-oxo esters and diketones with Geotrichum sp. G38 and its application to the syntheses of the key intermediates of several bioactive compounds such as (R)-denopamine 8, (R)-fluoxetine 11 and (2S, 3R)-sitophilate 14 were described.
Palladium(II)-Catalyzed Exchange and Isomerization Reactions. 17. Exchange of Chiral Allyl Alcohols with Hydroxide, Methoxide, and Phenyl at High [Cl<sup>-</sup>]. Stereochemistry of the Wacker Reaction
作者:Othman Hamed、Patrick M. Henry、Charles Thompson
DOI:10.1021/jo9906274
日期:1999.10.1
At high [Cl-] (> 2.0 M), PdCl42- catalyzes the exchange of chiral allylic alcohols with hydroxy, methoxy, and phenyl to give chiral allyl-substituted olefins. With unsymmetrical olefins, isomerization occurs along with exchange. The hydroxyl exchange occurs in aqueous solution while the other exchanges are carried out in methanol solution. At low [Cl-] (0.1 M) oxidation to the corresponding beta-hydroxy-, methoxy-, and phenyl-substituted carbonyl compounds occurred. The absolute configurations of the oxidation and exchange products should be the same if the same mode of addition to the Pd(II)-pi-complex is operative. The absolute configurations of the oxidation and exchange products for the phenylation reaction were the same, while for hydroxy and methoxy they were different. This result indicates methanol and water must have different stereochemistries of addition at high and low [Cl-]. Thus, previous studies showing anti hydroxypalladation at high [Cl-] are not valid indicators of the stereochemistry at low [Cl-]. If anti addition occurs at high [Cl-], the addition must be syn at low [Cl-].
FAUVE, ANNIE;VESCHAMBRE, HENRI, J. ORG. CHEM., 53,(1988) N2, C. 5215-5219