1998 Fiscal Year Final Research Report Summary
Design of Y-P-Y type Chiral Ligands Affording An Effective Chiral Field and Their Application to Asymmetric Reactions
| Project/Area Number |
09650964
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
YAMAGISHI Takamichi Tokyo Metropolitan University, Graduate School of Engineering, Department of Applied Chemistry, Professor, 大学院・工学研究科, 教授 (70087302)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAGISHI Takamichi Tokyo Metropolitan University, Graduate School of Engineering, Department of App (70087302)
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| Project Period (FY) |
1997 – 1998
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| Keywords | N-P-N ligands / Phosphinediamine Ligands / Bis (oxazolinyl) phosphine Ligands / Selective Ligation / P-chirality / Asymmetric Hydrogenation / Asymmetric Allylic Alkylation |
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| Research Abstract |
P-Chiral phosphine ligands are effective ligands for asymmetric reactions such asymmetric hydrogenation, but they have synthetic difficulties including optical resolution and suffer racemization at higher temperatures. Symmetrical N-P-N ligands would be expected to form a P-chirality if selective ligation of one of N-units to metals occurs ant to construct an effective chiral filed for asymmetric reactions. The presence of chiral centers in the N-P-N ligand skeleton would afford a large deviation between diastereomeric metal complexes. As chiral N-P-N ligands, phosphinediamine ligands 1 having phenethylamine units and bis(oxazolinyl)phosphine ligands 2 were prepared from corresponding chiral phenethylamine and chiral 2- phenyloxazoline by ortho-lithiation and phosphination with dichiorophosphine. Using these ligands, selective ligation of one of N-units to metal occurred for metal complexes, such as [Rh(nbd)_2]BF_4, PdCl_2(PhCN)_2 and K_2PtCl_4, and one of two diastereomeric complexes was formed selectively to afford P-chiral complexes. Substituent on phosphorus atom affects the deviation in the diastereomeric mixture and reversed P-chirality formation was supposed for PN2-Ph (1a) and PN2-iPr(lb) ligands.
PN2-Metal complexes were applied to the asymmetric reactions ; In the asymmetric hydrogenation of acrylic acid derivatives, Rh-1b complex could afford high %ees more than 90 %ee for the reduction of 2-methylcinnamic acid. In the asymmetric allylic alkylation by Pd-PN2-R(1) catalyst opposite configurations of the product were induced by using (S, S)-1a and (S, S)-lb ligands.
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