| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Ketenes are generally unstable and reactive species, and only a few stable monomeric ketenes are available. Ketenes are known as useful reagents since they have unique reactivity due to their characterisric sutucture. However, because of their lack of stability, application over a wide area in organic synthesis has not been achieved so far. This research project is concerned with the development of novel stereoselective reactions, novel type of reactions using a ketene as a key intermediate.
It is well known that beta-lactams can be synthesized by the reaction between a ketene and an imine. Since beta-lactams structure is a fundamental skeleton found in an important class of antibiotics, we first examined the development of new asymmetric methodology by using a chiral imine. As a result, it was found that a chiral imine derived from 1-(2,6-dichlorophenyl) ethylamine gave the corresponding beta-lactams in good to excellent yields with high stereoselectivity. Next, we designed a ketene having a chiral oxazolidinone auxiliary derived from erythro-2-amino-1,2-diphenylethanol. The ketene was easily prepared from the corresponding carboxylic acid via dehydration reaction with a 2-chloropyridinium salt. The reaction of the ketene with inines proceeded smoothly to give the desired beta-lactams with almost comlete stereoselectivity. Ketenes are also known to react with alkenes as well as imines to afford cyclobutanones. So, next we investigated intramolecular [2+2] cycloaddition reaction of chiral ketenes having a double bond. As a result, we found that the reaction proceeded smoothly to give the corresponding cyclobutanone derivatives with high stereoselectivity.
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