2006 Fiscal Year Final Research Report Summary
Development of Unique Synthetic Reactions of Ethenetricarboxylate Derivatives using Lewis Acid
| Project/Area Number |
17550036
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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 | Nara University of Education |
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Principal Investigator |
YAMAZAKI Shoko Nara University of Education, Faculty of Education, Professor, 教育学部, 教授 (50182481)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Ethenetricarboxylate / Propargyl Alcohol / Methylenetetrahydrofuran / Conjugate Addition-Cyclization / Lewis Acid / Substituted Propargyl Alcohol / Friedel-Crafts Reaction / Indole |
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| Research Abstract |
1) Nitrogen and oxygen-containing five-membered heterocycles such as pyrrolidines, including proline and related amino acids, and tetrahydrofurans are important core structures in organic chemistry because of their presence in many natural products and their biological activity. In this work, a new zinc and indium-promoted conjugate addition-cyclization reaction to afford nitrogen and oxygen-containing five-membered heterocycles has been developed. Reaction of ethenetricarboxylates and methylenemalonate 1 with propargylamines (1 equiv) in the presence of InBr_3-Et_3N (0.2 equiv.) at 80 ℃ for 4 h afforded methylenepyrrolidines in 73-75% yields. Reaction of 1 with propargyl alcohol in the presence of ZnBr_2 or InBr_3 at 80 ℃ afforded tetrahydrofurans in 66-89% yields. Substituted propargyl alcohols were also examined. Reaction of 1 and γ-silicon-substituted propargyl alcohols with ZnBr_2 at 80-110 ℃ led to (Z)-silicon-substituted products stereoselectively. Reaction of 1 and γ-ester-subs
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tituted propargyl alcohol 2 with ZnBr_2 gave (Z)-ester-substituted products stereoselectively. On the other hand, reaction of 1 and 2 with SnCl_4 at r.t. gave E-substituted tetrahydrofurans exclusively. Thus, interesting Lewis acid-dependency on stereoselectivity for the reaction of 2 was found. Reaction of a-substituted propargyl alcohols also gave cyclized products.
2) The Friedel-Crafts reaction is an important reaction for the formation of new C-C bonds. Recently, catalytic enantioselective Friedel-Crafts reaction of alkylidene malonates has been reported. However, the substituents in alkylidene malonates are limited. In order to explore new substituents such as carboxyl and carbonyl groups, catalytic enantioselective Friedel-Crafts reactions of reactive ethenetricarboxylates and acyl-substituted methylenemalonates 1 were investigated. The reaction of 1 with indoles in the presence of catalytic amounts of chiral bisoxazoline cupper(II) complex (10%) in THE at room temperature gave alkylated products in high yields and up to 95% ee. The enantioselectivity can be explained by the secondary orbital interaction on approach of indole to the less hindered side of the 1-Cu(II)-ligand complex. Less
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