Development of useful lanthanide salt-induced cascade reactions and applications to natural products synthesis
| Project/Area Number |
13672240
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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 | MEIJI PHARMACEUTICAL UNIVERSITY |
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Principal Investigator |
NAGAOKA Hiroto MEIJI PHARMACEUTICAL UNIVERSITY FACULTY OF PHARMACY PROFESSOR, 薬学部, 教授 (30155915)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2001: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Samarium(II) iodide / cyclization / reductive coupling / gibberellins / 10-oxatricyclo[4.3.2.0^<1,5>] undecane-7, 11-diones / 11-oxatricyclo[5.3.2.0^<1,6>]undecane-8, 12-diones / spiro[4, 4]nonane / 10-oxatricyclo[4.3.2.0^<1.5>]undecane |
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| Research Abstract |
Much interest is presently being directed to reaction using lanthanide reagent in organic synthesis. Especially, samarium(II) iodide (SmI_2) has been effective in carbon-carbon bond forming reactions and considerable attention has been focused on various intramolecular processes. In the present investigation, we developed an effective SmI_2-induced cascade cyclization to form polycyclic compounds. Treatment of (2Z)-2-methyl-7-oxodec-2-ene-1, 10-dioic acid derivatives with SmI_2 in tetrahydrofuran caused cascade reductive cyclization-Dieckmann condensation-lactonization to give 6-methyl-10-oxatricyclo[4.3.2.0^<1,5>]undecane-7, 11-diones corresponding to A/B ring system of antheridiogen-An and gibberellins. And reaction of dimethyl (2Z)-2-methyl-8-oxoundec-2-ene-1, 10-dioate with SmI_2 gave 7-methyl-11-oxatricyclo[5.3.2.0^<1,6>]undecane-8, 12-diones corresponding to A/B ring system of resenolactone. A partial structure of ginkgolides, 7-oxatricyclo[6.3.0.0^<1,5>]undecan-6-one system, was also synthesized by similar method. An application of the cascade cyclization for the synthesis of gibberellins was then investigated. The construction of the C/D ring system involves two crucial steps : stereoselective photo cyclization of 2-cyclohexene derivative with allene to form 8-methylenebicyclo[4.2.0]octan-2-one system and SmI_2-induced pinacol coupling reaction. The SmI_2-induced cascade cyclization of the (2Z)-2-methyl-7-oxods-2-ene1, 10-dioate derivative bearing C/D ring system produced fully functionalized gibbane skeleton in good yield.
Thus the authors established an effective and direct one-step process for obtaining bicyclic ring systems with γ-lactone from simple acyclic compounds using one electron transfer reagent SmI_2. By these mild conditions, the use of strongly basic conditions for the Dieckmann condensation is avoided and good to excellent stereocontrol over newly formed ring junctures in the product is possible.
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Report
(3 results)
Research Products
(9 results)
