1995 Fiscal Year Final Research Report Summary
Exploration of Diels-Alder Reaction of 2-Vinylazoles as 1-Azadienes
| Project/Area Number |
06672121
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Chemical pharmacy
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| Research Institution | Meiji College of Pharmacy |
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Principal Investigator |
SAKAMOTO Masanori Meiji College of Pharmacy, Department of Pharmaceutical Sciences, Professor, 薬学部, 教授 (70087774)
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| Project Period (FY) |
1994 – 1995
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| Keywords | 1-Azadiene / 2-Vinylazoles / Diels-Alder reaction / Endo selective / Tandem reaction |
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| Research Abstract |
Nitrogen containing a six-membered ring system (piperidine ring) is a common partial structure of biologically active compounds. One of the most direct approaches to the system is the nitorogen containing hetero Diels-Alder reaction. 1 However, Diels-Alder reaction of 1-aza-1, 3-butadienes, simple alpha, beta-unsaturated imines, themselves have been difficult due to their low reactivities as dienes, side reactions and instabilities arising from the imine moieties. We found benzylidenecyanomethyl-1, 3-benzothiazoles and -1, 3-benzoxazoles (1) as 1-aza-1, 3-butadienes. The dienes (1) featuring the stabilized imine moieties by constituting heteroaromatic rings, react with both electron-deficient and electron-rich dienophiles. It was found that substrates having the diene systems and dienophiles moiety in the molecules smoothly caused stereoselective intramolecular Diels-Alder reaction to give polycyclic compounds via exo-transition state. Ethyl (E)-3-(1, 3-benzothiazol-2-yl)-3-cyanopropenoate (2) as 1-aza-1, 3-butadiene (2), bearing electronwithdrawing ester group at diene -4-position, reacts with electron -rich dienophiles under extremely mild conditions to give corresponding cycloadducts with regio-and endo-selectivities. Treatment of 2 with electron-donating allyl alcohols causes tandem transesterification and intramolecular cycloaddition to afford cis-fused polycyclic systems in a single step.
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