| Project/Area Number |
14370719
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | The University of Tokyo |
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Principal Investigator |
OHAWADA Tomohiko The University of Tokyo, Graduate School of Pharmaceutical Sciences, Professor, 大学院・薬学系研究科, 教授 (20177025)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIYAMA Masanobu The University of Tokyo, Graduate School of Pharmaceutical Sciences, Lecturer, 大学院・薬学系研究科, 講師 (00271916)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥10,700,000 (Direct Cost: ¥10,700,000)
Fiscal Year 2003: ¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 2002: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Keywords | amide / nitrogen pyramidalized amide / twisted amide / 7-azabicyclo[2.2.1]hepatane / solution structure / density-functional theory / ピラミッドアミド / アミド構造 / 回転バリアー / ペフチド・タンパク質 / α-らせん構造 / 7-azabicyclo[2.2.1]hetane / 金属アート錯体 / ベンザイン / 非平面アミド |
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| Research Abstract |
We showed that amides of bicyclic 7-azabicyclo[2.2.1]heptane are intrinsically nitrogen-pyramidal. Single-crystal X-ray diffraction structures of some relevant bicyclic amides, including the prototype N-benzoyl-7-azabicyclo[2.2.1]heptane, exhibited nitrogen-pyramidalization in the solid state. We evaluated the rotational barriers about the amide bonds of various N-benzoyl-7-azabicyclo[2.2.1]heptanes in solution. The observed reduction of the rotational barriers of the bicyclic amides, as compared with those of the monocyclic pyrrolidine amides, is consistent with a nitrogen-pyramidal structure of 7-azabicyclo[2.2.1]heptane amides in solution. A good correlation was found between the magnitudes of the rotational barrier of N-benzoyl 7-azabicyclo[2.2.1]heptanes bearing para-substituents on the benzoyl group and the Hammett's δ_p^+ constants. Calculations with the density-functional theory reproduced the nitrogen-pyramidal structures of these bicyclic amides as energy minima. The calculated magnitudes of electron delocalization from the nitrogen non--bonding nH orbital to the carbonyl π^* orbital of the amide group evaluated by application of the bond model theory, correlated well with the rotational barriers of a variety of amides, including amides of 7-azabicyclo[2.2.1]heptane. Non-planarity of the amide nitrogen of 7-azabicyclo[2.2.1]heptanes would be derived from nitrogen-pyramidalization due to the CNC angle strain, and twisting of the amide bond due to the allylic strain.
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