Comparison of the Reaction Mechanism of N- and S- ylide rearrangement : A Quantum Theoretical Study
| Project/Area Number |
10671992
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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 | Nagoya City University |
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Principal Investigator |
SHIRAI Naohiro Nagoya City University, Faculty of Pharmaceutical Sciences, Assistant Professor, 薬学部, 講師 (80080208)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | ylide / sigmatropic rearrangement / allyl rearrangement / benzyl rearrangement / early transition state / ab initio / (p-d) pai ineraction / interaction of lone pair electron with pai electron / (p-d)π相互作用 / allyl転位 / benzyl転位 / MOPAC / ab intio / B3LYP / 6-31G* / 遷移状態 |
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| Research Abstract |
When a reactant has two different active points (allyl group and benzyl group) in the molecule in [2,3] sigmatropic rearrangement of N- or S- ylides, the experimental results showed that selectivity of the N-ylide was poor and the S-ylide gave only one product. Difference of the chemoselectivity was investigated by molecular orbital theory.
Geometries of the ylides and the transition state of the [2,3] sigmatropic rearrangement were optimized by various calculation levels and energy barriers for the reaction were estimated. Semi-empirical calculations failed to analyze the reason of the difference. Ab initio calculations with Density Functional Method (B3L YP/6-31GィイD1*ィエD1 level show that the transition states of the N-ylide rearrangement are early transition structures and those of the S-ylide are late transition structures. These transition structures are much affected by reactivity of the ylides. Lone pair electron of S atom stabilize the S-ylide to give the late transition structure. Result of this study verified the Evans-Polanyi Proposal.
In the process of this research program, it was found that interaction of lone pair electron on S atom with π system of phenyl ring influence conformation of the sulfonium salt. The influence was quantitatively analyzed by B3LYP/6-31GィイD1*ィエD1.
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Report
(3 results)
Research Products
(3 results)
