2006 Fiscal Year Final Research Report Summary
The stereoselective synthesis of P-chiral phosphines through the additions onto the P=C double bond of prochiral phosphaalkenes
| Project/Area Number |
17550107
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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 | Osaka City University |
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Principal Investigator |
MINAMI Tatsuya Osaka City University, Graduate School of Engineering, Associate Professor, 大学院工学研究科 (70251931)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Phosphapalladacyclopropanes / Alkoxypalladation / Arylphosphaalkenes / P-C-S pincer ligand / P-chiral phosphines / Thiophosphine |
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| Research Abstract |
(1) Diastereoselective Synthesis of Phosphapalladacyclopropanes by Alkoxypalladation of Arylphosphaalkenes Bearing ortho-Benzylic Heteroatom Substituent
Alkoxypalladation of the kinetically protected arylphosphaalkenes bearing a coordinative heteroatom substituent at the ortho-benzylic positeion gave the phosphapalladacyclopropane complexes stereoselectively. The complexes were found to be stable to silica gel chromatography in the air. The benzylic heteroatom substituent of arylphosphaalkenes acts as the ligand of the resulting palladium (II) complexes. The diastereoselectivity of this reaction is mainly controlled by the heteroatom substituent at the benzylic stereogenic center. We have found a novel approach for the synthesis of enantio-pure P-C-S pincer ligand coordinated palladium complexes.
(2) Nucleophilic Addition of Thiolate Anion to Tricarbonylchromium-Coordinated Arylphospaalkenes
The stereoselective additions onto the P=C double bond of prochiral phosphaalkenes are one of the efficient method for the synthesis of P-chiral phosphines. However, the reactivity of sterically protected phosphaalkenes, which are stable in the air, is rather low. Tricarbonylchromium-coordinated arylphosphaalkenes are expected to increase the reactivity toward nucleophiles, because the tricarbonylchromium fragment stabilizes benzylic carbanions due to its strong electron-withdrawing ability. Although (E)-2-phenyl-1-(2,4,6-tri-t-butylphenyl)phosphaethene did not reacted with lithium thiolate in THF, the corresponding chromium complex gave thiophosphine in excellent yield. We have found a new method for the synthesis of bulky P-chiral ligands.
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