1998 Fiscal Year Final Research Report Summary
A Novel Controlling Method for Regio- and Stereoselectivity in the Carbonyl-Allylation using Allylic Tin Reagents
| Project/Area Number |
09640636
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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 |
Organic chemistry
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| Research Institution | SHIMANE UNIVERSITY |
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Principal Investigator |
TAKUWA Akio Shimane University・Interdisciplinary Faculty of Science and Engineering・Professor, 総合理工学部, 教授 (70032456)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIGAICHI Yutaka Shimane University・Interdisciplinary Faculty of Science and Engineering・Assistan, 総合理工学部, 助教授 (00212118)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Allyltin / Pentadienyltin / Carbonyl Compound / Allylation / Regioselectivity / Stereoselectivity / Photoinduced Electron Transfer / Lewis Acid |
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| Research Abstract |
In the light promoted reaction of gamma -substituted allyltin reagents with carbonyl compounds, the allylic groups could be introduced predominantly at their a-position into carbonyl carbon via single electron-transfer from allylic tin reagent to the photoexcited triplet carbonyl compounds. The photoinduced alpha-allylation proceeds stereospecifically, for example, (E)- and (Z)-gamma-alkoxyallylic tin reagents give (R)- and (Z)-a-homoallylic alcohols. The photoinduced allylic 1,3-rearrangement has been also investigated in detail by direct excitation of y -substituted allyltin compounds.
In the reaction between a-alkoxyaldehydes and pentadienyltin, each of the possible four regio- and stereolsomers, syn-gamma-, anti-gamma-, syn-epsilon-, and syn-e-adducts, was selectively synthesized by the use of an appropriated combination of alkoxy groups. Lewis acids, and solvents. When MgBr2 was used as Lewis acid, the protecting a-oxygenated aldehyde such as benzyl (Bn) or methoxymethyl (MOM) affoided gamma-syn-adduct, but the combination of BF3OEt2 with a-protected aldehyde by tert-butyldimethylsilyl (TBS) gave a-anti-adduct, On the other hand, SnCI4 was found to give syn-gamma-adduct in the reaction with the benzyl protected aldehyde, When the reaction of the aldehyde protected by TBS was performed in the presence of InCl3 in ethanol media, gamma-anti-adduct was produced. Thus, the regio- and stereocontrolled allylation and pentadienylation of carbonyl group could be achieved by a appropriate combination of the reaction promoter and the protecting group of aldehyde.
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