2007 Fiscal Year Final Research Report Summary
Synthesis of Hypervalent Organoantimony Compounds and Their Utilization for Organic Synthesis
| Project/Area Number |
17590022
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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 |
Chemical pharmacy
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| Research Institution | Hokuriku University |
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Principal Investigator |
KURITA Jyoji Hokuriku University, Faculty of Pharmaceutical Sciences, Professor (80100494)
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| Co-Investigator(Kenkyū-buntansha) |
KAKUSAWA Naoki Hokuriku University, Faculty of Pharmaceutical Sciences, Research Associate (20185721)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Antimony / Hypervalent Compounds / Sb-N Trans-annular Interaction / 1, 5-Azastibocine / Cross-coupling / Reduction / N-Arylation / Transition-metal Catalyst |
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| Research Abstract |
The aim of this research program was focused on development of new synthetic reaction by use of pseudo-tetravalent and -pentavalent organoantimony compounds and we disclosed the following new synthetic reactions.
1. Hypervalent Organoantimony Compounds 12-Ethynyl- and 12-aryl-tetrahydrodibenz[c.f][1.5] azastibocines: Highly Efficient New Transmetallatine Agent for Organic Halides: An efficient C-C bond formation of acyl chlorides, aryl iodides and bromides was demonstrated by palladium-catalyzed cross-coupling reaction of the title compounds under mild conditions. Single crystal X-ray analysis of the ethynyl-1, 5-azastibocine revealed that the remarkable reactivity enhancement of the azastibocine was derived from elongation of the antimony-ethynyl carbon bond originated from Sb-N intramolecular non-bonding interaction.
2. Reduction of Nitroarenes to Azoxyarenes with Sb-Alkyl-1, 5-Azastibocine/Bezoin System: During our continuous researches on organoantimony compounds, we found that Sb-al
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kyl-1, 5-azastibocine (1 eq) can react with nitroarene to give azoxyarene and 1, 5-azastibocine oxide. Further investigation revealed that a catalytic amount of the azastibocine was enough for the reduction, because the oxide could be transformed to the azastibocine by reduction with benzoin which was oxidized to benzil. Thus, various nitroarenes were reacted with the azastibocine (0.15 eq) in the presence of benzoine (2 eq) to afford the corresponding azoxy compound in good yields. The results showed that the Sb-alkyl-1, 5-azastibocine was a mild reducing agent with wide applicability.
3. Cu-Mediated Ullmann-Type N-Arylation by Use of Acetoxytetraarylstiborane: The traditional Ullmann-type condensation is a typical method for aryl-nitrogen bond formation. We disclosed now a simple and mild method for Cu-mediated Ullmann-type Narylation of various amines by use of acetoxytetraaryl-stiboranes (Ar_4SbOAc 1) as a novel aryl donnor. The reaction of Ar_4SbOAc with amines in the presence of stoichiometric amount of copper(II) acetate and triethylamine in dichloromethane affords the corresponding N-arylated products in good yield. The reaction has wide generality and can he applied to both aliphatic and aromatic amines. Especially the reaction with electron-rich aromatic amines proceeds efficiently giving N-arylated products in satisfactory yields. It should be emphasized that the arylation can be carried under aerobic condition without care of exogenous oxygen and moisture. Less
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