2007 Fiscal Year Final Research Report Summary
Study on Reactive Small Molecules of Sulfur Generated by the Methods of Organic Chemistry
| Project/Area Number |
16350019
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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 |
Organic chemistry
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| Research Institution | Saitama University |
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Principal Investigator |
NAKAYAMA Juzo Saitama University, Graduate school of Science and Engineering, Professor (90092022)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIHARA Yoshiaki Saitama University, Graduate school of Science and Engineering, Associate Professor (00272279)
ISHII Akihiko Saitama University, Graduate school of Science and Engineering, Professor (90193242)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Diatomic sulfur / Triatomic sulfur / Sulfur monoxide / Disulfur monoxide / Addition reaction / Diels-Alder reaction / Singlet SO / Thiirene oxide |
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| Research Abstract |
The following reactive small molecules of sulfur were generated from the organic sources and their chemistry was investigated: 1) diatomic sulfur (S_2) that corresponds to a sulfur analogue of molecular oxygen O_2, 2) triatomic sulfur (S_3) that corresponds to a sulfur analogue of ozone O_3, 3) sulfur monoxide (SO) where one of the oxygen atoms of O2 is replaced by sulfur, and 4) disulfur monoxide (S_2O) where one of the oxygen atoms of sulfur dioxide (S_2O) is replaced by S.
The bicylic compound that carries an -S-SO- bridge underwent a retro-Diels-Alder reaction to extrude disulfur monoxide (S=S=O) in a reversible way at room temperature in solution. The resulting S=S=O undergoes a disproportionation through self-dimerization to give S_3 and SO_2 in the absence of suitable trapping agents. The S_3 acts as a 1, 3-dipole just like ozone and underwent 1, 3-dipolar cycloaddition toward strained alkenes, for example, norbornene. On the other hand, the S=S=O is trapped by dienes and other r
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eagents in good yields. Reactivities and DFT calucations of the molecule leads to a conclusion that S=S^+-0 is the major contributor of the ground state of this reactive species.
The Diels-Alder adduct that was formed by Diels-Alder reaction of a thiophene 1-oxide with dimethyl acetylenedicarboxylate underwent the SO extrusion at room temperature in solution with a driving force of the formation of a benzene derivative. The resulting SO was found to undergo hitherto unknown cycloadditions, i.e., [1+2] cycloadditions to alkenes and alkynes to give thiirane oxides and thiirene oxides, respectively. In particular, the later [1+2] cycloaddition to alkynes is synthetically important as a synthetic method of thiirene 1-oxide. It also undergoes [1+4] cycloadditions to acyclic dienes and cyclic dienes (polyenes) to provide a variety of cyclic sulfoxides; the addition to cyclic dienes is stereospecific. The reactivities of the SO leads to a conclusion that the SO produced by the present method is singlet and reacted with trapping agents without decay to more stable triplet state.
In addition, a few new reactions that generate diatomic sulfur(S_2) were developed. Less
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