- Biferrocene-based diphosphine ligands: Synthesis and application of walphos analogues in asymmetric hydrogenations
-
A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments (R)-1-(N,N-dimethylamino)ethylferrocene and (SFc)-2- bromoiodoferrocene. The molecular structures of (SFc)-2- bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl2(L)] and [RuCl(p-cymene)(L)]PF6) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands.
- Zirakzadeh, Afrooz,Gross, Manuela A.,Wang, Yaping,Mereiter, Kurt,Spindler, Felix,Weissensteiner, Walter
-
supporting information
p. 1075 - 1084
(2013/04/23)
-
- Enantioselective hydrogenation of α-aryloxy and α-alkoxy α,β-unsaturated carboxylic acids catalyzed by chiral spiro iridium/phosphino-oxazoline complexes
-
The iridium-catalyzed highly enantioselective hydrogenation of α-aryloxy and α-alkoxy-substituted α,β-unsaturated carboxylic acids was developed. By using chiral spiro phosphino-oxazoline ligands, the hydrogenation proceeded smoothly to produce various α-aryloxy- and α-alkoxy-substituted carboxylic acids with extremely high enantioselectivities (ee up to 99.8%) and reactivities (TON up to 10 000) under mild conditions. The hydrogenation of R-benzyloxy-substituted α,β-unsaturated acids provided an efficient alternative for the synthesis of chiral R-hydroxy acids after an easy deprotection. A mechanism involving a catalytic cycle between IrI and IrIII was proposed on the basis of the coordination model of the unsaturated acids with the iridium metal center. The rationality of the catalytic cycle, with an olefin dihydride complex as the key intermediate, was supported by the deuterium-labeling studies. The X-ray diffraction analysis of the single crystal of catalyst revealed that the rigid and sterically hindered chiral environment created by the spiro phosphino-oxazoline ligands is the essential factor that permits the catalyst to obtain excellent chiral discrimination. A chiral induction model was suggested on the basis of the catalyst structure and the product configuration.
- Li, Shen,Zhu, Shou-Fei,Xie, Jian-Hua,Song, Song,Zhang, Can-Ming,Zhou, Qi-Lin
-
supporting information; experimental part
p. 1172 - 1179
(2010/04/01)
-
- Design, synthesis, and structure-activity relationship of carbamate-tethered aryl propanoic acids as novel PPARα/γ dual agonists
-
We have developed a new class of PPARα/γ dual agonists, which show excellent agonistic activity in PPARα/γ transactivation assay. In particular, (R)-9d was identified as a potent PPARα/γ dual agonist with EC50s of 0.377 μM in PPARα and 0.136 μM in PPARγ, respectively. Interestingly, the structure-activity relationship revealed that the stereochemistry of the identified PPARα/γ dual agonists significantly affects their agonistic activities in PPARα than in PPARγ.
- Kim, Nam-Jung,Lee, Kwang-Ok,Koo, Bon-Woong,Li, Funan,Yoo, Ja-Kyung,Park, Hyun-Ju,Min, Kyung-Hoon,Lim, Joong In,Kim, Mi Kyung,Kim, Jin-Kwan,Suh, Young-Ger
-
p. 3595 - 3598
(2008/02/11)
-
- Synthesis of a peroxime proliferator activated receptor (PPAR) α/γ agonist via stereocontrolled Williamson ether synthesis and stereospecific SN2 reaction of S-2-chloro propionic acid with phenoxides
-
The stereospecific synthesis of the PPAR α/γ agonist 1 was accomplished via ethylation of the optically pure trihydroxy derivative 6, itself derived via an enzymatic resolution. The ethylation can be accomplished without epimerization only under strict control of the reaction conditions and the choice of base (sodium tert-amylate), temperature (-30°C), order of addition, and solvent (DMF). The key diastereospecific SN2 reaction of the phenol 4 with S-2-chloropropionic acid is best achieved via the sodium phenoxide of 4 derived from Na0 as the reagent of choice. The structure elucidation and key purification protocols to achieve pharmaceutical purity will also be described
- Aikins, James A.,Haurez, Michael,Rizzo, John R.,Van Hoeck, Jean-Pierre,Brione, Willy,Kestemont, Jean-Paul,Stevens, Christophe,Lemair, Xavier,Stephenson, Gregory A.,Marlot, Eric,Forst, Mindy,Houpis, Ioannis N.
-
p. 4695 - 4705
(2007/10/03)
-
- Synthesis of PPAR agonist via asymmetric hydrogenation of a cinnamic acid derivative and stereospecific displacement of (S)-2-chloropropionic acid
-
(Chemical Equation Presented) The synthesis of the peroxime proliferator activated receptor (PPAR) α,γ-agonist (1) was accomplished with high enantio- and diastereoselectivity by employing an asymmetric hydrogenation strategy, of an α-alkoxy cinnamic acid
- Houpis, Ioannis N.,Patterson, Lawrence E.,Alt, Charles A.,Rizzo, John R.,Zhang, Tony Y.,Haurez, Michael
-
p. 1947 - 1950
(2007/10/03)
-
- Process
-
The present invention relates to novel resolution methods, which are useful in the preparation of enantiomerically enriched intermediates which in their turn are useful in the prepartion of compounds with a pharmacological effect on the insulin resistance syndrome (IRS). It is such a process that the present inventions sets out to define, and more particularly for the preparation of the (S)-enantioner of certain 2-ethoxy-3-(4-hydroxyphenyl)propanoic acids and derivatives thereof.
- -
-
-
- Process for the preparation of 3-aryl-2-hydroxy propanoic acid
-
The present invention relates to an improved process for the preparation of 3-aryl-2-hydroxy propanoic acid derivatives of the formula (1) 1useful as an intermediate for the preparation of many pharmaceutically active compounds.
- -
-
-
- 3-aryl-2-hydroxypropionic acid derivative III
-
A novel 3-aryl-2-hydroxypropionic acid derivative, a process and intermediate for its manufacture, pharmaceutical prepartions containing it and the use of the compound in clinical conditions associated with insulin resistance.
- -
-
-