1986 Fiscal Year Final Research Report Summary
Development of Highly Selective Reactions Based on Novel Ring Transformations
| Project/Area Number |
60470093
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Synthetic chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
OHSHIRO Yoshiki Osaka University Professor, 工学部, 助教授 (70028984)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAO Toshikazu Osaka University Lecturer, 工学部, 助手 (90116088)
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| Project Period (FY) |
1985 – 1986
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| Keywords | GEM-FUNCTIONALIZATION / RING-OPENING CARBONYLATION / REDUCTIVE DECONJUGATION / TETRACARBONYL NICKEL / DIALKYL PHOSPHONATE / ホスホン酸ジアルキル |
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| Research Abstract |
Highly selective reactions have been developed by novel transformations of gem-dibromocyclopropanes which are prepared by the addition of dibromocarbene to olefins or silyl enol ethers. A successful utilization of silylamines in the Ni <(CO)_4> -induced carbonylation reactions of gem-dibromocyclopropanes contributes one-step stereoselective gem-functionalization of cyclopropanes. This transformation is considered to be achieved by the attack of intermediary nickel enolates on electrophiles. gem-Dibromocyclopropanes bearing the chloro or chloromethyl (or mesyloxymethyl) substituent at the vicinal position underwent the Ni <(CO)_4> -induced ring-opening carbonylation reactions with alcohols or amines leading to the <beta> , <gamma> - or <gamma> , <delta> -unsaturated carboxylic acid derivatives, respectively. Use of a silylamine resulted in condensation with an electrophile with the enolates of the corresponding carboxylic acid derivatives. The addition of dibromocarbene to silyl ketene acetals gave <alpha> -bromo- <alpha> , <beta> -unsaturated carbonyl compounds via spontaneous ring-opening of gem-dibromosiloxycyclopropanes. Reductive deconjugation of thus obtained <alpha> -bromo- <alpha> , <beta> -unsaturated esters or lactones was performed by treatment with dialkyl phosphonate and triethylamine to yield the corresponding <beta> , <gamma> -unsaturated compounds stereoselectively. Both methods were efficiently applied to the synthesis of the naturally occurring compound, pyrenophorin.
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